Co-culture with Tetragenococcus halophilus changed the response of Zygosaccharomyces rouxii to salt stress

Process Biochemistry xxx (xxxx) xxx–xxx

Contents lists available at ScienceDirect

Process Biochemistry journal homepage: www.elsevier.com/locate/procbio

Co-culture with Tetragenococcus halophilus changed the response of Zygosaccharomyces rouxii to salt stress Shangjie Yaoa,b, Rongqing Zhoua,b, Yao Jina,b, Liqiang Zhangc, Jun Huanga,b, Chongde Wua,b,* a

College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu 610065, China c Luzhou Pinchuang Technology CO.,LTD, Luzhou 646000, China b

A R T I C LE I N FO

A B S T R A C T

Keywords: Zygosaccharomyces rouxii Tetragenococcus halophilus Co-culture Salt stress

Zygosaccharomyces rouxii and Tetragenococcus halophilus exhibit remarkable salt tolerance and play roles in highsalt fermented food production. This study investigated the effect of co-culture with T. halophilus on Z. rouxii based on analysis of the viability of Z. rouxii in high-salt environments, the plasma membrane integrity, Na+, K+-ATPase activity, amino acid content of Z. rouxii cell after salt stress and organic acids assay. The results showed both T. halophilus broth supernatant and intracellular component of T. halophilus increased the viability of Z. rouxii in the 12 % environment. Co-cultured Z. rouxii cells maintained better plasma membrane integrity and lowered Na+, K+-ATPase activity than single-cultured after salt stress. Co-cultured Z. rouxii cells exhibited higher contents of aspartic acid, threonine, serine, asparagine, glutamic acid, alanine, α-amino-n-butyric acid, methionine, homo-cystine, arginine and proline compared with single-cultured after salt stress. More contents of propionic acid, lactic acid and L-pyroglutamic acid and lower contents of L-malic acid and citric acid were detected in co-culture broth. This study shows preculture of T. halophilus and then co-culture with Z. rouxii enhanced the viability of Z. rouxii in high-salt environment. The results may contribute to further understand the interactions between Z. rouxii and T. halophilus in high-salt environments.

1. Introduction The production of traditional fermented foods such as soy sauce, sauerkraut and bean paste with a salty taste and distinct fragrance is the result of the actions of microorganisms or their enzymes [1]. Salt is the indispensable additive as a flavor modifier and preservative agent for traditional fermented foods, for instance, the high-salt liquid fermented soy sauce in Japan contains about 18 % salt and the low-salt solid fermented soy sauce in China contains about 8 % salt [2,3]. Salt can suppress the occurrence and growth of mold and some yeasts which are able to cause spoilage and faster growing bacteria including Listeria monocytogenes and Staphylococcus aureus, and its preservative property contributes to the development of aroma, flavor and color of fermented products and the enhancement of shelf life [4,5]. However, high saline environment can result in cells plasmolysis, and the intracellular water molecules could infiltrate out of cells that cause inhibition even death of microorganism [6,7]. It was reported that the increase of salinity resulted in the reduction of community richness and decrease of community diversity, some microorganisms such as Bacteroidetes phylum could produce endospores to resist extreme conditions outside [8]. In

⁎

addition, high salinity can destroy enzyme structure and reduce the metabolic enzyme activity thus slow down the fermentation [9]. Microorganisms counteract salt stress by adopting multiple energetic-costly mechanisms which alter energy homeostasis of the cell and, finally, reduce microbial growth [10]. Changing proteomic size and expression of several genes, enhancing energy production by substrate-level phosphorylation and the anaplerotic function of the TCA cycle were generally reported to be the mechanisms adopted by microorganism to counteract high salinity [11–13]. For Zygosaccharomyces rouxii, multiple mechanisms were employed to help it counteract salt stress challenges including reshaping cell wall and plasma membrane integrity and fluidity, accumulating K+ and extruding Na+ via pump located in cell membrane, production and accumulation of osmolytes such as glycerol, trehalose, arabitol, mannitol and erythritol [14]. In order to further improve the quality and safety of fermented foods, co-culture of microbes was employed during the manufacture of fermented foods. Microbial co-culture was found to be able to enhance microbial activity, alter protein expression profiles, and subsequently contribute to the flavor and safety performance of fermented food [15–17]. Lim et al. [18] suggested that co-culture with Saccharomyces

Corresponding author at: College of Biomass Science and Engineering, Sichuan University, Sichuan University, Chengdu 610065, China. E-mail address: [email protected] (C. Wu).

https://doi.org/10.1016/j.procbio.2020.02.021 Received 4 October 2019; Received in revised form 18 February 2020; Accepted 21 February 2020 1359-5113/ © 2020 Elsevier Ltd. All rights reserved.

Please cite this article as: Shangjie Yao, et al., Process Biochemistry, https://doi.org/10.1016/j.procbio.2020.02.021

Process Biochemistry xxx (xxxx) xxx–xxx

S. Yao, et al.

mL) was inoculated into 30 mL MRS broth in a sterile syringe, and grown statically at 30 °C for 4 h. 0.5 mL cell suspension of Z. rouxii (2.5 × 107 CFU/mL) was inoculated into 30 mL MRS broth in another sterile syringe. The syringes were connected to each other with sterile filters (JINTENG, Tianjing) of 25 mm diameter and 0.22 μm pore size, respectively. And they were grown statically at 30 °C for 4 h. The media of the syringes was manually mixed every 1 h. As for single culture of Z. rouxii, 30 mL MRS broth was inoculated with 0.5 mL cell suspension of Z. rouxii in a sterile syringe which was connected to other one sterile syringe containing 30 mL fresh MRS broth.

cerevisiae EC-1118 enhanced the viability of Lactobacillus rhamnosus HN001, and analysis of the interactions between these cells showed that the direct cell-cell contact co-aggregation mediated by yeast cell surface and/or cell wall components or metabolites contributed to the viabilityenhanced ability. Romanens et al. [19] developed anti-fungal LAB-yeast co-cultures which completely inhibited growth of the citrinin-producing strain Penicillium citrinum, the potentially fumonisin-producing strain Gibberella moniliformis and the aflatoxin-producer Aspergillus flavus. Although co-culture has been applied during the production of fermented foods, the relationship among microbes remains unclear. Both Zygosaccharomyces rouxii and Tetragenococcus halophilus exist pervasively in traditional fermented foods and play an active role in flavor development [20,21]. According to our previous research, the presence of T. halophilus contributed to the accumulation of acids and esters in broth and played a role in flavor change of fermented food [22]. In addition, co-culture of these strains improved the content of ethanol, 2-methyl-1-propanol, 4-hydroxy-2,5-dimethyl-3(2 H)-furanone, maltol and reduced the content of biogenic amines during the manufacture of soy sauce [23]. As common halotolerant microorganisms, the salt-tolerant mechanisms of Z. rouxii and T. halophilus have been well documented [14,24,25]. In this study, in order to further understand the interactions between Z. rouxii and T. halophilus in highsalt environments, the response to salt treatment of Z. rouxii and the effect of co-culture with T. halophilus on the physiological characterization of Z. rouxii were investigated. These results may contribute to further elucidate the interaction between T. halophilus and Z. rouxii, and improve the efficiency of food fermentation.

2.3. Cell viability assessment of Z. rouxii cell in high saline environment after co-culture When explored the effect of first-step culture on cell viability of Z. rouxii, the cells of Z. rouxii were grown in direct co- and single-culture media containing 6% NaCl. During first-step culture, T. halophilus was cultured with different cultivation times (0 h, 2 h, 4 h and 6 h), then coculture broth was inoculated with Z. rouxii and grown statically at 30 °C for 4 h. Cell suspensions of single-culture and co-culture were serially diluted, and 10 μL of the cell suspensions were spotted in YEPD agar medium containing 0.01 % chloramphenicol (Sangon Biotech, Shanghai) with 6% and 12 % salt contents, respectively. Subsequently, the plates were incubated at 30 °C for 48 h, and then plates containing 5–100 CFU were counted. For exploration of the effect of co-culture on cell viability of Z. rouxii, the cells of Z. rouxii were grown by direct co-culture and singleculture in MRS broth containing 6% NaCl and collected at 2 hourly intervals for 8 h. Live cells count method was described as above.

2. Materials and methods 2.1. Strains and cultivation conditions

2.4. Cell viability assessment of Z. rouxii cell in high saline environment after co-culture with different components of T. halophilus

The yeast and lactic acid bacteria (LAB) strains used in this study were Z. rouxii CGMCC 3791 and T. halophilus CGMCC 3792, respectively. Z. rouxii CGMCC 3791 and T. halophilus CGMCC 3792 were isolated in our laboratory from horsebean chili paste and soya sauce moromi, respectively. Z. rouxii CGMCC 3791 was identified via physiological, biochemical, and 26S rDNA sequence analysis. T. halophilus CGMCC 3792 was identified via physiological, biochemical, and 16S rDNA sequence analysis [26]. Then the strains were stored in China General Microbiological Culture Collection Center (CGMCC). The strains were stored at −80 °C with 30 % glycerol. Z. rouxii and T. halophilus cultures were inoculated into yeast extract peptone dextrose (YEPD) and MRS (de Man, Rogosa, Sharp) media (OXOID, United Kingdom) both containing 6% m/v NaCl, respectively and were incubated at 30 °C for 24 h. Then the cell suspension was inoculated with an inoculum size of 5% into 100 mL fresh YEPD medium and MRS medium both containing 6% NaCl, respectively. After incubation statically at 30 °C for 24 h, the cells were collected by centrifugation at 10,000 g for 10 min, and resuspended in 4 mL sterile water.

T. halophilus cells and T. halophilus broth supernatant were obtained by centrifuging 25 mL preculture at 10,000 g for 10 min at 4 °C. And the cells were resuspended in 1.5 mL sterile water, and supernatant was filtered with a 0.22-μm sterile filter. Similarly, the T. halophilus cells of from another 25 mL culture were obtained by centrifugation and resuspended in 1.5 mL PBS buffer (pH 7.0) and used to harvest intracellular components. The cells were disrupted by using an ultrasonic cell disruptor (JY92-11 N, SCIENTZ, Ningbo) with a Φ2 amplitude transformer for 25 min (ultrasound 4 s with 1 s interval) in ice bath. Intracellular components of T. halophilus were obtained by centrifugation at 12,000 g for 10 min at 4 °C. 0.5 mL Z. rouxii cell suspension (2.5 × 107 CFU/mL) were inoculated into culture systems containing different cellular components (A, 1.5 mL cell suspension of T. halophilus. B, 15 mL T. halophilus broth supernatant. C, 1.5 mL intracellular components of T. halophilus. D, 15 mL T. halophilus broth supernatant and 1.5 mL intracellular components of T. halophilus) and 30 mL fresh MRS broth were inoculated with 0.5 mL cell suspension of Z. rouxii as singleculture (E). Fresh MRS broth was added to make the volume of every group be 32 mL. They were grown statically at 30 °C for 4 h. Subsequently, cell viability assessment in the 12 % salinity environment was proceed as the method described as above.

2.2. Co-culture of T. halophilus and Z. rouxii In this study, two kinds of co-culture patterns (direct co-culture and indirect co-culture) were employed in laboratory condition (Fig. 1). As for direct co-culture, 1 mL cell suspension of T. halophilus (2.5 × 108 CFU/mL) obtained above was inoculated to 30 mL MRS broth and grown statically at 30 °C for 4 h, unless explicitly stated. The culture of T. halophilus in co-culture broth before inoculation with yeast was set as first-step culture. Then, the broth was inoculated with 0.5 mL cell suspension of Z. rouxii (2.5 × 107 CFU/mL) and co-cultured statically at 30 °C for 4 h, unless explicitly stated. Single-culture of T. halophilus and Z. rouxii was performed as control. Indirect co-culture of T. halophilus and Z. rouxii was performed according to method described by Ruiz et al. [17]. Briefly, 1 mL suspension of T. halophilus (2.5 × 108 CFU/

2.5. Organic acids determination of co-culture fermentation broth The fermentation broth supernatant from direct co-culture and single-culture was collected respectively by centrifugation at 10,000 g for 10 min at 4 °C, treated by activated organic acid C18E tubes (Welch, Shanghai) and filtered with a 0.22-μm sterile filter. Organic acid contents of fermentation broth were analyzed by using HPLC and UV–vis detector (1260, Aglient, American) with a Waters Symmetry C18 column (300 × 6.5 mm, GRACE, Columbia, American) according to the method reported by Zong et al. [27]. The mobile phase consisted of 9.00 mM H2SO4 buffer solution, using an isocratic elution procedure 2

Process Biochemistry xxx (xxxx) xxx–xxx

S. Yao, et al.

Fig. 1. Direct co-culture (A) and indirect co-culture (B) used in this study.

with a flow rate of 0.6 mL/min. The Waters Symmetry C18 column was kept at 75 °C. Detection was performed at 215 nm. Standard solutions of lactic acid, acetic acid, succinic acid, propionic acid, citric acid, L-malic acid, tartaric acid and L-pyroglutamic acid were prepared separately in ultrapure water.

Intracellular amino acids were extracted and collected by centrifugation at 12,000 g for 10 min. 10 % m/v sulfosalicylic acid solution was added in the collected supernatant in the ratio of 1:1. Samples were placed statically at 4 °C for 1 h. After centrifugation at 12,000 g for 10 min and filtration with a 0.22-μm sterile filter, intracellular amino acids were determined by an automatic amino acid analyzer (A300, membraPure GmbH, Germany). Mixed amino acid standards (membraPure GmbH, Germany) were used to identify and quantify amino acids in samples. The dry cell weight (DCW) was determined, and the intracellular amino acid contents were expressed as μg/mg DCW.

2.6. Plasma membrane integrity analysis of Z. rouxii The method of plasma membrane integrity analysis of Z. rouxii was performed based on previous report [28]. Briefly, Z. rouxii cells grown by indirect co- and single-culture containing 6% NaCl at 30 °C for 4 h statically were washed once after centrifugation at 8000 g for 10 min. The cells were resuspended in 4 mL MRS broth containing 6% and 12 % NaCl, respectively and salt stress was performed at 30 °C for 2 h. After that, cells were washed once after centrifugation at 8000 g for 10 min and resuspended in normal saline to an OD600 of 1.3. O-nitrophenyl-bD-galactopyranoside (ONPG) (Sigma-Aldrich, St. Louis, USA) was added to a final concentration of 400 μg mL−1 and the samples were placed at 30 °C for 30 h. The level of ONP was monitored by a spectrophotometer (UV-2450; Shimadzu) at 420 nm.

2.9. Statistical analysis All analyses were conducted in triplicate. Significant differences were tested by one-way analysis of variance (ANOVA) using IBM SPSS Statistics Software (version 22) at p < 0.05 and Tukey’s test was applied for comparison of means. 3. Results 3.1. First-step culture enhanced the viability of Z. rouxii in the high saline environment

2.7. The plasma membrane Na+, K+-ATPase activity analysis of Z. rouxii Z. rouxii cells grown by indirect co- and single-culture containing 6% NaCl at 30 °C for 4 h statically were washed once after centrifugation at 8000 g for 10 min and resuspended in 4 mL MRS broth containing 6%, 12 % and 18 % NaCl, respectively. After salt treatment at 30 °C for 2 h, the cells were washed once after centrifugation at 8000 g for 10 min. The method for analysis of the activity of Na+, K +-ATPase was based on the content of pi produced when Na+, K +-ATPase catalyzed hydrolysis of ATP [29]. The cells were disrupted by using the ultrasonic cell disruptor above to obtain cell homogenate. The cell homogenate was treated according to the Na+, K+-ATPase activity assay kit (Nanjing Jiancheng Bioengineering Institute, China). The content of pi was determined with a spectrophotometer (TU-1901, PERSEE, Beijing) at 636 nm. Protein content was measured by the Coomassie brilliant blue method [30], and the activity of Na+, K+ATPase was expressed as μmol pi released/mg protein per hour at 37 °C.

Previous research showed that co-culture with lactic acid bacteria enhanced the cell viability of yeast, and the sequence of microbial inoculation also played important roles in cell activity [31]. Generally, the growth of lactic acid bacteria led to the decrease of pH by generation of lactic acid and other organic acids, which contributed to the growth of yeast [32,33]. Thus, in this study, the effect of first-step culture time of T. halophilus on the cell viability of Z. rouxii was investigated (Fig. 2). As shown in Fig. 2, there was no difference between the live cell counts of Z. rouxii in single-culture and co-culture after 0, 2 and 4 h for first-step culture and 4 h for co-culture, when the medium contained 6% NaCl. The live cell count of Z. rouxii in co-culture after 6 h for first-step culture was significantly lower than that in each group above. When the medium contained 12 % NaCl, no difference between the live cell count of Z. rouxii in single-culture and co-culture after 0 h for first-step culture was observed. However, with the increase in firststep culture time from 0 h to 6 h, the cell number of Z. rouxii increased gradually. When the first-step culture time was 2 h, the live cell count in co-culture after 2 h for first-step culture exceeded that in single-culture by about 0.39 × 106 CFU/mL. Co-culture enhanced the live cell count of Z. rouxii after 4 and 6 h for first-step culture by about 3.07 and 3.71 folds compared with that in single-culture, respectively. These results

2.8. Intracellular amino acids determination of Z. rouxii Z. rouxii cells prepared as Section 2.7 were washed once after centrifugation at 8000 g for 10 min and resuspended in 1 mL PBS buffer (pH 7.0). Cells were damaged by boiling water bath for 30 min. 3

Process Biochemistry xxx (xxxx) xxx–xxx

S. Yao, et al.

Fig. 2. Cell count of Z. rouxii in singe- (control) and co-culture with different first-step culture time (0 h, 2 h, 4 h and 6 h). Cell number of Z. rouxii was counted in YEPD agar medium containing 6% (A) and 12 % (B) salt. Significantly different (P > 0.05) values are marked with different lowercase letters.

(12 % salt content) with appropriate co-culture time (4 and 6 h).

suggested that some metabolites which contributed to the viability of Z. rouxii in the high saline environment.

3.3. Broth supernatant or intracellular components of T. halophilus enhanced the viability of Z. rouxii in the high saline environment

3.2. Co-culture enhanced the viability of Z. rouxii in the high saline environment

In order to investigate whether either extracellular or intracellular components of T. halophilus can enhance the viability of Z. rouxii in high saline environment, the co-culture assay was performed by replacing T. halophilus cell suspension with the extracellular or intracellular compositions of T. halophilus. Fig. 4 shows that the live cell counts of Z. rouxii after co-culture with different components of T. halophilus. The results showed that the live cell counts of Z. rouxii after co-culture with cell suspension of T. halophilus, T. halophilus broth supernatant and intracellular components of T. halophilus were about 2.01, 2.15 and 1.74 × 106 CFU/mL, respectively, which were higher than that obtained in single-culture (E, 0.91 × 106 CFU/mL). The viability-enhancing effect on Z. rouxii was not observed when Z. rouxii was cocultured with broth supernatant and intracellular components of T. halophilus, and the live cell count was about 0.92 × 106 CFU/mL.

To explore the effect of co-culture on the cell viability of Z. rouxii, T. halophilus and Z. rouxii were inoculated in co-culture broth, incubated with different cultivation times, and the cell viability was determined. (Fig. 3). Fig. 3 showed that live cell count of Z. rouxii in medium containing 6% and 12 % salt contents increased with the increment of coculture time. In addition, the live cell count in the 6% salinity environment was higher than that in the 12 % salinity environment, significantly. When the co-culture time was 0, 2, 4 and 6 h, there was no difference between live cell counts of Z. rouxii in single- and co-culture in the 6% salinity environment. Higher number of live Z. rouxii cells in single-culture at 8 h was observed than that in co-culture, and this may be ascribed to the lack of nutrition in co-culture system. In addition, it was interesting to note that in the 12 % salinity environment, co-culture with T. halophilus for 4 and 6 h enhanced the viability of Z. rouxii by about 48 % and 29 %, respectively. While the co-culture time was 8 h, there was no difference between live cell counts of Z. rouxii in singleand co-culture. These results suggested that co-culture showed cell viability-enhanced ability for Z. rouxii in the high saline environment

3.4. Organic acids distribution in co-culture fermentation broth In order to investigate the effect of co-culture on the organic acid production, the organic acid contents in co-culture broth, T. halophilus

Fig. 3. Cell count of Z. rouxii in singe- and co-culture with different co-culture time (0 h, 2 h, 4 h, 6 h and 8 h). Cell number of Z. rouxii was counted in YEPD agar medium containing 6% (A) and 12 % (B) salt. Asterisk indicates significantly different (P < 0.05) of cell counts in singe- and co-culture. 4

Process Biochemistry xxx (xxxx) xxx–xxx

S. Yao, et al.

Fig. 6. Effect of 6 and 12 % (w/v) salt concentrations on plasma membrane integrity. Relative OD was the ratio of OD value at 420 nm to the maximum OD value in the study of plasma membrane integrity. Asterisk indicates significantly different (P < 0.05) in single- and co-culture after salt stress with same salt content.

Fig. 4. Cell count of Z. rouxii in singe- and direct co-culture with different cellular components (A, 1.5 mL cell suspension of T. halophilus. B, 15 mL T. halophilus broth supernatant. C, 1.5 mL intracellular compounts of T. halophilus. D, 15 mL T. halophilus broth supernatant and 1.5 mL intracellular components of T. halophilus. E, single culture). Significantly different (P > 0.05) values are marked with different lowercase letters.

3.5. Co-culture benefited the plasma membrane integrity of Z. rouxii Plasma membrane integrity of Z. rouxii was evaluated by using the β-galactosidase substrate ONPG as a probe. ONPG can be cleaved by βgalactosidase that resulted in the formation of ONP, and higher OD420nm value indicated higher level of ONP. As shown in Fig. 6, the relative OD420nm value of samples containing substrate cleavage by βgalactosidase after salt stress with 12 % salt was higher than that stressed with 6% salt. When the salt content increased from 6% to 12 % under salt stress, 53.51 % higher of OD420nm value was observed in single-culture samples. Similarly, 31.33 % higher of OD420nm value was observed in co-culture samples. After salt stress with 6% salt content, the relative OD420nm value in co-culture was lower than that in singleculture by 21.38 %. After salt stress with 12 % salt content, the relative OD420nm value in co-culture was lower than that in single-culture by 33.11 %. These results suggested that high salt stress led to increased plasma membrane permeability of Z. rouxii, while co-culture with T. halophilus decreased the degree of plasma membrane damage.

3.6. Co-culture reduced the plasma membrane Na+, K+-ATPase activity of Z. rouxii Fig. 5. Effect of co-culture on organic acid distributions in four kinds of fermentation broth. Significantly different (P > 0.05) values are marked with different lowercase letters.

Na+, K+-ATPase is a widely recognized biomarker for evaluating salinity adaptation [34]. Fig. 7 shows the result of the plasma membrane Na+, K+-ATPase activity of Z. rouxii incubated in single-culture and co-culture and then shocked by salt stress. As the salt content increasing from 6% to 18 %, both the plasma membrane Na+, K+-ATPase activities of Z. rouxii from single-culture and co-culture increased. A detailed comparison in Na+, K+-ATPase activity between single-culture and co-culture showed that cells collected from single-culture exhibited significantly higher activity than those from co-culture with the increase in salt content. When cultured in medium containing 6% NaCl, the plasma membrane Na+, K+-ATPase activity of Z. rouxii in co-culture was similar to that in single-culture. When cultivated in higher salt contents (12 % and 18 %), 22.47 % and 48.97 % higher activities were observed in single-culture cells than co-culture cells, respectively. These results indicated that co-culture contributed to maintain stable Na+, K+-ATPase activity during salt stress, suggesting that co-culture with T. halophilus enhanced the salt tolerance of Z. rouxii and Z. rouxii did not need higher Na+, K+-ATPase activity to protect itself away from salt damage compared with single-culture.

broth, Z. rouxii broth and MRS broth were measured (Fig. 5). As shown in Fig. 5, 8 kinds of acids including L-malic acid, propionic acid, lactic acid, tartaric acid, acetic acid, citric acid, L-pyroglutamic acid and succinic acid were detected. For the concentration of tartaric acid, acetic acid and succinic acid, there was no difference in 4 kinds of fermentation broth. Compared to single-culture of Z. rouxii, singleculture of T. halophilus exhibited higher contents of L-malic acid, propionic acid, lactic acid and L-pyrogulatamic acid. Therefore, the presence of T. halophilus led to higher contents of propionic acid, lactic acid, and L-pyrogulatamic acid in fermented food. In addition, the concentration of L-malic acid in co-culture broth was 1.27 g/L which was lower than that in monoculture of T. halophilus broth and Z. rouxii broth. The concentration of citric acid was about 1.23 g/L in co-culture broth and T. halophilus broth, and it was lower than that in Z. rouxii broth and MRS broth.

5

Process Biochemistry xxx (xxxx) xxx–xxx

S. Yao, et al.

serine, asparagine, glycine, alanine, α-amino-n-butyric acid, methionine, homo-cystine, arginine and proline were detected compared with that in single-culture. These results showed that co-culture with T. halophilus slowed the decline of contents of intracellular amino acids in Z. rouxii when faced to high salt stress. 4. Discussion In order to uncover the interactions between Z. rouxii and T. halophilus under salt stress, the response of Z. rouxii to salt treatment and the effect of co-culture with T. halophilus on cell activity and physiological characterization of Z. rouxii were investigated. Generally, the growth of lactic acid bacteria decreased the pH of medium, which favored the growth of yeast, and the first-step culture of lactic acid bacteria was important for the construction of co-culture system [31,35]. Thus, in this study, the effect of first-step culture of T. halophilus on the viability of Z. rouxii was firstly investigated (Fig. 2). As expected, the first-step culture had a positive effect on the growth of Z. rouxii under salt stress, and the viable cell number of Z. rouxii increased with the extension of the first-step culture time (Fig. 2). As we know, the metabolites including sugars, amino acids, fatty acids, organic acids, and living cells of T. halophilus accumulated during the first-step culture [36]. Although it was not yet clear how the metabolites or T. halophilus cells enhanced the salt tolerance of Z. rouxii, the first-step culture of T. halophilus in culture had a positive impact on the salt tolerance of Z. rouxii. In addition, it was worth noting that acidic conditions proposed by the first-step culture of T. halophilus may contribute to the reinforcement of salt tolerance of Z. rouxii under salt stress. Previous researches also suggested that acid adaptation increased salt tolerance of cell by inducing cross protection [37,38]. In addition, we investigated the effect of co-culture time on the viability of Z. rouxii during salt stress (Fig. 3). The results demonstrated that coculture with T. halophilus for 4–6 h benefited the salt tolerance of Z. rouxii (Fig. 3). With the increase in co-culture time, the viability-enhancing effect of co-culture was not observed, which may result from the lack of nutrients or competition for nutrients. In addition, the accumulation of lactic acid may inhibit the growth of Z. rouxii [39]. For instance, Hudecová et al. [40] found that the co-cultivation with the commercial LAB significantly reduced the growth rate of G. candidum

Fig. 7. The plasma membrane Na+, K+-ATPase activity of Z. rouxii after salt stress with 6%, 12 % and 18 % salt content. Asterisk indicates significantly different (P < 0.05) in singe- and co-culture after salt stress with same salt content.

3.7. Co-culture changed the distribution of intracellular amino acids in Z. rouxii Effect of co-culture on the contents of intracellular amino acids in Z. rouxii was investigated (Table 1). According to the result, 17 kinds of amino acids were detected in Z. rouxii cells. Compared with 6% salinity, the content of intracellular amino acids in Z. rouxii was significantly lower after salt stress with 12 % and 18 % salinity. A detailed comparison of amino acid contents between co-culture and single-culture showed that with 6% salinity, the contents of aspartic acid, serine, asparagine, α-amino-n-butyric acid, phenylalanine, arginine and proline in co-culture were higher than those in single-culture. Similarly, 4 amino acids (aspartic acid, α-amino-n-butyric acid, cysteine and proline) exhibited higher contents in Z. rouxii cells in co-culture compared with single-culture after salt stress with 12 % salinity. As for co-culture after 18 % of salt treatment, higher contents of aspartic acid, threonine,

Table 1 The intracellular amino acid contents of Z. rouxii from indirect co-culture and single-culture after salt treatment. Amino acid content (μg/mg DCW)

Salt content (%) 6

Asp Thr Ser Asn Glu Gly Ala Cit a-ABA (Cys)2 Cystha Met Phe H-Cysteine Lys Arg Pro

12

18

Co-culture

Single-culture

Co-culture

Single-culture

Co-culture

Single-culture

0.76 ± 0Aa 0.33 ± 0A 0.88 ± 0.01Aa 3.34 ± 0.04Aa 0.35 ± 0.25A 0.43 ± 0A 0.81 ± 0.01A 0.09 ± 0.02B 0.23 ± 0Aa 0.2 ± 0A 0.63 ± 0.03A 0.21 ± 0.01A 0.32 ± 0.02Aa 1.04 ± 0.05A 1.45 ± 0.01A 1.81 ± 0.04Aa 0.7 ± 0.07Aa

0.64 ± 0.04Ab 0.31 ± 0.01A 0.73 ± 0.01Ab 3.03 ± 0.03Ab 0.34 ± 0.23A 0.38 ± 0.04A 0.81 ± 0.02A 0.1 ± 0.01B 0.19 ± 0.03Ab 0.19 ± 0.02A 0.42 ± 0.18A 0.19 ± 0.03A 0.25 ± 0.05Ab 0.88 ± 0.02A 1.4 ± 0.03A 1.52 ± 0.03Ab 0.52 ± 0.07Ab

0.15 ± 0.03Ba 0.11 ± 0.02B 0.34 ± 0.06B 1.14 ± 0.21B 0.03 ± 0B 0.23 ± 0.04B 0.69 ± 0.15A 0.2 ± 0.03A 0.1 ± 0.01Ba 0.11 ± 0Ba 0.4 ± 0.05B 0.1 ± 0.01B 0.22 ± 0.12AB 0.56 ± 0.06B 0.37 ± 0.06B 0.19 ± 0.02B 0.43 ± 0.02Ba

0.09 ± 0.02Bb 0.09 ± 0.01B 0.25 ± 0.04B 0.95 ± 0.2B 0.03 ± 0.01B 0.18 ± 0.04B 0.6 ± 0.14B 0.16 ± 0.03A 0.08 ± 0Bb 0.07 ± 0.01Bb 0.31 ± 0.02B 0.08 ± 0.01B 0.15 ± 0.02B 0.48 ± 0.03B 0.33 ± 0.06B 0.15 ± 0.02B 0.31 ± 0.04Bb

0.09 ± 0.02Ba 0.07 ± 0.02Ca 0.19 ± 0.03Ca 0.43 ± 0.01Ca 0.08 ± 0.06AB 0.15 ± 0Ca 0.26 ± 0.01Ba 0.07 ± 0.01B 0.1 ± 0Ba 0.09 ± 0.02B 0.29 ± 0.13B 0.07 ± 0.01Ca 0.13 ± 0.03B 0.34 ± 0.27Ba 0.2 ± 0.01C 0.18 ± 0.02Ba 0.19 ± 0.02Ca

0.05 ± 0.01Cb 0.03 ± 0.01Cb 0.14 ± 0.03Cb 0.29 ± 0.03Cb 0.02 ± 0.01B 0.11 ± 0.01Cb 0.19 ± 0Cb 0.07 ± 0.01C 0.07 ± 0.01Bb 0.05 ± 0.02B 0.28 ± 0.03B 0.05 ± 0.01Cb 0.13 ± 0.08B 0.32 ± 0.15Bb 0.15 ± 0.06C 0.12 ± 0.02Bb 0.1 ± 0.04Cb

The contents of an amino acid in Z. rouxii form co-culture after salt stress with different salt contents (6%, 12 % and 18 %) are significantly different (P < 0.05) with different uppercase. The contents of an amino acid in Z. rouxii form single-culture after salt stress with different salt contents (6%, 12 % and 18 %) are significantly different (P < 0.05) with different uppercase. The contents of an amino acid in Z. rouxii after salt stress with same salt content are significantly different (P < 0.05) with different lowercase. 6

Process Biochemistry xxx (xxxx) xxx–xxx

S. Yao, et al.

aggregation [14,47,48]. Na+, K+-ATPase, as an enzyme, exists in plasma membrane and plays a crucial role in creating electrochemical gradients that drive ion transport [49]. For most euryhaline organisms, there will be some saltadaptive changes in Na+, K+-ATPase activity after salt stress [50]. In this study, the results indicated that the Na+, K+-ATPase activity in Z. rouxii increased when the salt content increased from 6% to 18 % (Fig. 6). It was interesting that Z. rouxii exhibited lower Na+, K+-ATPase activity in co-culture compared with single-culture. Similar to the plasma membrane integrity analysis, we believed that several physiological alterations induced by co-culture help Z. rouxii restore osmotic balance. At the transcriptome level, 9 genes involved in oxidative phosphorylation and encoding ATP synthase significantly down-regulated in Z. rouxii cells from co-cultured system compared with that in single-cultured cells [22]. It may verify co-culture resulted in inhibition of ATP synthesis and had a negative effect on Na+, K+-ATPase activity when faced to salt stress. It was demonstrated that more than one hundred proteins showed increased expressions in yeasts after salt stress, and many of the proteins played a role in the cellular response to increased osmolarity including glycerol production [51]. Under salt stress, some proteins involving in the oxidative stress defense, the amino acids and ubiquinone biosynthesis or the pyruvate and acetate metabolism were shown to be upregulated in salt adapted mitochondria of Saccharomyces cerevisiae, and some outer mitochondrial membrane proteins mainly glycolytic enzymes showed up-regulated [52]. A rapid biosynthesis of specific proteins will cause a rapid amino acid depletion [53]. In addition, the damage of plasma membrane will result in a loss of amino acids out of cells. The above all were able to explain the content of amino acids dropped with the increase of salt content from 6% to 18 % (Table 1). By contrast, the co-culture with T. halophilus was able to enhanced the content of some amino acids in Z. rouxii cells under relatively low salinity including aspartic acid, threonine, serine, asparagine, glutamic acid, alanine, α-amino-n-butyric acid, methionine, homo-cystine, arginine and proline. After salt stress with high salinity, co-culture slowed down the depletion and loss of amino acids. It was interesting that the expression of multiple genes involved in glycine, serine and threonine metabolism pathway, cysteine and methionine metabolism pathway and protein synthesis was found down-regulated after co-culture compared with single-culture [22]. It was verified that direct physical contact between yeast and LAB was not required for yeast-LAB interaction, and amino acids were the major agents of the interaction [54]. In addition, it was reported that Na+, K+-ATPase activity after harsh salinity was correlated with glycine levels and the internally accumulated proline was able to protect cells from damage or death caused by high osmolarities as a compatible solute [55,56].

during in milk, and competition for nutrients and space, substances (lactic, acetic acids, phenyllactic and pyroglutamic acids) and decrease of pH were believed to be the reason for the reduction of growth rate. In order to further explore the potential metabolites existed in T. halophilus which contribute to the growth and salt tolerance of Z. rouxii, cell components of T. halophilus were harvested and the effect of intracellular and extracellular components on the growth was determined (Fig. 4). The results showed that both fermentation supernatant (B) and intracellular fluid (C) of T. halophilus contributed to the growth of Z. rouxii (Fig. 4). This result suggested that living cells of T. halophilus were not indispensable for the viability-enhancing effect, and the addition of intracellular fluid and broth supernatant containing specific metabolites may promote the growth of Z. rouxii. Previous researches reported some compounds cell wall derivatives or metabolites existed in yeast supernatant and YM broth that could contribute to the adhering properties and auto-aggregation of L. rhamnosus [18]. In addition, it is interesting to note that the mixture of intracellular fluid and broth supernatant (D) failed to exhibit the viability-enhancing effect, and it may result from certain hydrolases in intracellular fluid and broth supernatant. Therefore, the further analysis of exact composition of the intracellular fluid and broth supernatant was necessary to verify the presence of the protective metabolites. Organic acids are important components influencing the organoleptic properties of fermented foods during fermentation [41], in this study, the effect of co-culture on the production organic acid was therefore determined (Fig. 5). A total of 8 organic acids were monitored, and no obvious difference was observed in contents of tartaric acid, acetic acid and succinic acid in single culture and co-culture systems. As for single culture, T. halophilus was the contributor of Lmalic acid, propionic acid, lactic acid and L-pyroglutamic acid, and Z. rouxii accumulated higher content of critic acid. Thus, higher contents of propionic acid, lactic acid and L-pyroglutamic and lower content of citric acid were detected in the co-culture with T. halophilus (Fig. 5). However, it is interesting to note that lower content of L-malic acid was measured in co-culture system compared with single-culture of Z. rouxii. Generally, L-malic acid can be secreted from microbial cells, and three metabolic pathways are involved in the biosynthesis of L-malic acid from glucose including nonoxidative pathway, oxidative pathway and glyoxylate cycle [42]. In the malolactic fermentation, L-malic acid is converted into L-lactic acid and CO2 by malolactic bacteria [43]. The cause of this lower content of L-malic acid in co-culture broth compared with the other three broths for two possible reasons. Z. rouxii competed for nutrients (mainly glucose) with T. halophilus and Z. rouxii did not affect the malolactic activity although Z. rouxii inhibited the growth of T. halophilus [44]. Integrity and fluidity of plasma membrane are important for osmo tolerance of yeast. The integrity and fluidity are the safeguarding of turgor pressure which can counteract the force driving water across the osmotic gradient into or out the cell [14]. According to the result of the plasma membrane integrity analysis, the increase of salt content led to the increase of plasma membrane damage of Z. rouxii, while co-culture cells exhibited better cell membrane integrity (Fig. 6). Cell integrity is critical in maintaining the viability and cellular metabolic functions [45]. Actin plays an essential role in membrane integrity and its assembly is mediated by Wiskott-Aldrich syndrome protein [46]. In our precedent study, the expression of gene ZYGR_0AK06260 encoding Wiskott-Aldrich syndrome protein was found up-regulated in Z. rouxii after co-culture compared with single-culture [22]. It suggested that coculture with T. halophilus had a positive effect on plasma membrane integrity and contributes to improve the cell viability and salt tolerance of Z. rouxii, which was in agreement with the results obtained in Fig. 3. In addition, some challenges such as acid stress brought by T. halophilus induced physiological alterations in the Z. rouxii cells which enabled cells to counteract salt stress and to restore osmotic balance. The physiological alterations may contain regulation of morphological and structural properties of the cell wall and plasma membrane and protein

5. Conclusion Recently, co-culture of LAB and yeasts is widely used in the production of fermented foods. To further understand the interaction between them, this study explored the effect of co-culutre with T. halophilus on the physilogical characterization of Z. rouxii under salt stress. The results showed that the cells collected from co-culture system exhibited better plasma membrane integrity and higher content of amino acids. In addtion, co-culture changed the organic acids distribution, and decreased the Na+, K+-ATPase activity of Z. rouxii. Generally, co-culture with T. halophilus changed the response of Z. rouxii to salt stress and benefited the cell viability of Z. rouxii in high saline enviroments. It suggested that a suitable inoculation of T. halophilus may benefit the proliferation of Z. rouxii and promote high salt fermenation. Results presented in this study laid the foundation for the industrial application of these specie.

7

Process Biochemistry xxx (xxxx) xxx–xxx

S. Yao, et al.

Author statement [18]

Manuscript title: Co-culture with Tetragenococcus halophilus changed the response of Zygosaccharomyces rouxii to salt stress (PRBI_2019_1294). I have made substantial contributions to the design and interpretation of data for the work. I have revised it critically for important intellectual content, and I have approved the final version to be published. I agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

[19]

[20]

[21]

[22]

Funding This work was supported by the National Natural Science Foundation of China (No. 31671849 and 31871787) and Sichuan University-Luzhou cooperation project (Grant number: 2017CDLZS18).

[23]

[24]

Declaration of Competing Interest [25]

The authors declare no competing financial interest. References

[26]

[1] S.N. Liu, Y. Han, Z.J. Zhou, Lactic acid bacteria in traditional fermented Chinese foods, Food Res. Int. 44 (2011) 643–651, https://doi.org/10.1016/j.foodres.2010. 12.034. [2] L. Hong, M. Wang, C. Wang, C. Wang, H. Wang, Analysis of salt-tolerance genes in Zygosaccharomyces rouxii, Appl. Biochem. Biotech. 170 (2013) 1417–1425, https:// doi.org/10.1007/s12010-013-0283-2. [3] P.J. Taormina, Implications of salt and sodium reduction on microbial food safety, Crit. Rev. Food Sci. Nutr. 50 (2010) 209–227, https://doi.org/10.1080/ 10408391003626207. [4] Y.R. Song, D.Y. Jeong, S.H. Baik, Effects of indigenous yeasts on physicochemical and microbial properties of Korean soy sauce prepared by low-salt fermentation, Food Microbiol. 51 (2015) 171–178, https://doi.org/10.1016/j.fm.2015.06.001. [5] G.H. Fleet, Chapter 5 – yeast spoilage of foods and beverages, Yeasts 1 (2011) 53–63, https://doi.org/10.1016/B978-0-444-52149-1.00005-7. [6] H. He, Y. Chen, L. Xiang, C. Yan, C. Yang, G. Zeng, Influence of salinity on microorganisms in activated sludge processes: a review, Int. Biodeterior. Biodegrad. 119 (2016) 520–527, https://doi.org/10.1016/j.ibiod.2016.10.007. [7] P.J. Taormina, Implications of salt and sodium reduction on microbial food safety, Crit. Rev. Food Sci. Nutr. 50 (2010) 209–227, https://doi.org/10.1080/ 10408391003626207. [8] Y. Chen, H. He, H. Liu, H. Li, G. Zeng, X. Xia, C. Yang, Effect of salinity on removal performance and activated sludge characteristics in sequencing batch reactors, Bioresour. Technol. 249 (2018) 890–899, https://doi.org/10.1016/j.biortech.2017. 10.092. [9] J. Hong, W. Li, B. Lin, M. Zhan, C. Liu, B.Y. Chen, Deciphering the effect of salinity on the performance of submerged membrane bioreactor for aquaculture of bacterial community, Desalination 316 (2013) 23–30, https://doi.org/10.1016/j.desal.2013. 01.015. [10] J.B. Russell, G.M. Cook, Energetics of bacterial growth: balance of anabolic and catabolic reactions, Microbiol. Mol. Biol. Rev. 59 (1995) 48–62, https://doi.org/10. 0000/PMID7708012. [11] Adaptation of Corynebacterium glutamicum to salt-stress conditions, Proteomics 10 (2010) 445–457, https://doi.org/10.1002/pmic.200900482. [12] R. Dhar, R. S?gesser, C. Weikert, J. Yuan, A. Wagner, Adaptation of Saccharomyces cerevisiae to saline stress through laboratory evolution, J. Evol. Biol. 24 (2011) 1135–1153, https://doi.org/10.1111/j.1420-9101.2011.02249.x. [13] P. Arense, V. Bernal, J.L. Iborra, M. Cánovas, Metabolic adaptation of Escherichia coli to long-term exposure to salt stress, Process Biochem. 45 (2019) 1459–1467, https://doi.org/10.1016/j.procbio.2010.05.022. [14] T.C. Dakal, L. Solieri, P. Giudici, Adaptive response and tolerance to sugar and salt stress in the food yeast Zygosaccharomyces rouxii, Int. J. Food Microbiol. 185 (2014) 140–157, https://doi.org/10.1016/j.ijfoodmicro.2014.05.015. [15] C. Wu, Z. Jia, J. Huang, R. Zhou, Reduced nitrite and biogenic amine concentrations and improved flavor components of Chinese sauerkraut via co-culture of Lactobacillus plantarum and Zygosaccharomyces rouxii, Ann. Microbiol. 64 (2014) 847–857, https://doi.org/10.1007/s13213-013-0724-8. [16] K.W. Hai, K.N. Yi, E. Koh, L. Yao, A.S. Chien, X.L. Hui, K.L. Yuan, RNA-Seq reveals transcriptomic interactions of Bacillus subtilis natto and Bifidobacterium animalis subsp. Lactis in whole soybean solid-state co-fermentation, Food Microbiol. 51 (2015) 25–32, https://doi.org/10.1016/j.fm.2015.04.012. [17] L. Ruiz, B. Sánchez, C.G.D.L. Reyes-Gavilán, M. Gueimonde, A. Margolles, Coculture of Bifidobacterium longum and Bifidobacterium breve alters their protein expression

[27]

[28]

[29]

[30] [31]

[32]

[33]

[34]

[35] [36]

[37]

[38]

[39]

[40]

[41]

8

profiles and enzymatic activities, Int. J. Food Microbiol. 133 (2009) 148–153, https://doi.org/10.1016/j.ijfoodmicro.2009.05.014. P.L. Lim, M. Toh, Q.L. Shao, Saccharomyces cerevisiae EC-1118 enhances the survivability of probiotic Lactobacillus rhamnosus HN001 in an acidic environment, Appl. Microbiol. Biot. 99 (2015) 1–9, https://doi.org/10.1007/s00253-015-6560-y. E. Romanens, S.F. Leischtfeld, A. Volland, M. Stevens, U. Krähenmann, D. Isele, B. Fischer, L. Meile, S.M. Schwenninger, Screening of lactic acid bacteria and yeast strains to select adapted anti-fungal co-cultures for cocoa bean fermentation, Int. J. Food Microbiol. 290 (2019) 262–272, https://doi.org/10.1016/j.ijfoodmicro.2018. 10.001. R. Harada, M. Yuzuki, K. Ito, K. Shiga, T. Bamba, E. Fukusaki, Microbe participation in aroma production during soy sauce fermentation, J. Biosci. Bioeng. 125 (2018) 688–694, https://doi.org/10.1016/j.jbiosc.2017.12.004. C. Escott, J. del Fresno, I. Loira, A. Morata, J. Suárez-Lepe, Zygosaccharomyces rouxii: control strategies and applications in food and winemaking, Fermentation 4 (2018) 69, https://doi.org/10.3390/fermentation4030069. S. Yao, R. Zhou, Y. Jin, J. Huang, C. Wu, Effect of co-culture with Tetragenococcus halophilus on the physiological characterization and transcription profiling of Zygosaccharomyces rouxii, Food Res. Int. 121 (2019) 348–358, https://doi.org/10. 1016/j.foodres.2019.03.053. P. Singracha, N. Niamsiri, W. Visessanguan, S. Lertsiri, A. Assavanig, Application of lactic acid bacteria and yeasts as starter cultures for reduced-salt soy sauce (moromi) fermentation, LWT-Food Sci. Technol. 78 (2017) 181–188, https://doi. org/10.1016/j.lwt.2016.12.019. L. Liu, L. Si, X. Meng, L. Luo, Comparative transcriptomic analysis reveals novel genes and regulatory mechanisms of Tetragenococcus halophilus in response to salt stress, J. Ind. Microbiol. Biotechnol. 42 (2015) 601–616, https://doi.org/10.1007/ s10295-014-1579-0. D. Wang, Z. Hao, J. Zhao, Y. Jin, J. Huang, R. Zhou, C. Wu, Comparative physiological and transcriptomic analyses reveal salt tolerance mechanisms of Zygosaccharomyces rouxii, Process Biochem. (2019), https://doi.org/10.1016/j. procbio.2019.04.009. C. Wu, C. Liu, G. He, J. Huang, R. Zhou, Characterization of a multiple-stress tolerance Tetragenococcus halophilus and application as starter culture in Chinese Horsebean-Chili-Paste manufacture for quality improvement, Food Sci. Technol. Res. 19 (2013) 855–864, https://doi.org/10.1016/j.procbio.2015.11.035. Y. Zong, J. Lin, H. Xu, Z. Jia, X. Yang, M.M.F. Choi, Optimization and validation of an hplc-photodiode array detector method for determination of organic acids in vinegar, J. AOAC Int. 98 (2015) 422, https://doi.org/10.5740/jaoacint.14-164. C. Wu, J. Zhang, M. Wang, G. Du, J. Chen, Lactobacillus casei combats acid stress by maintaining cell membrane functionality, J. Ind. Microbiol. Biotechnol. 39 (2012) 1031–1039, https://doi.org/10.1007/s10295-012-1104-2. Q. Zhao, L. Shao, X. Hu, G. Wu, J. Du, J. Xia, H. Qiu, Lipoxin A4 preconditioning and postconditioning protect myocardial ischemia/reperfusion injury in rats, Mediators Inflamm. 2013 (2013) 1–13, https://doi.org/10.1155/2013/231351. N.J. Kruger, The Bradford Method for Protein Quantitation, the Protein Protocols Handbook, Springer, 2009, pp. 17–24, https://doi.org/10.1385/0-89603-268-X:9. P.V.P. Devanthi, R. Linforth, H. Onyeaka, K. Gkatzionis, Effects of co-inoculation and sequential inoculation of Tetragenococcus halophilus and Zygosaccharomyces rouxii on soy sauce fermentation, Food Chem. 240 (2018) 1–8, https://doi.org/10. 1016/j.foodchem.2017.07.094. T.H. Gadaga, A.N. Mutukumira, J.A. Narvhus, The growth and interaction of yeasts and lactic acid bacteria isolated from Zimbabwean naturally fermented milk in UHT milk, Int. J. Food Microbiol. 68 (2001) 21–32, https://doi.org/10.1016/s01681605(01)00466-4. K. Ström, J. Schnürer, P. Melin, Co-cultivation of antifungal Lactobacillus plantarum MiLAB 393 and Aspergillus nidulans, evaluation of effects on fungal growth and protein expression, FEMS Microbiol. Lett. 246 (2005) 119–124, https://doi.org/10. 1016/j.femsle.2005.03.047. H. Yang, Y. Meng, Y. Song, Y. Tan, A. Warren, J. Li, X. Lin, Salinity fluctuation influencing biological adaptation: growth dynamics and Na(+) /K(+) -ATPase activity in a euryhaline bacterium, J. Basic Microbiol. 57 (2017), https://doi.org/ 10.1002/jobm.201700124. S.J. Rhee, J.E. Lee, C.H. Lee, Importance of lactic acid bacteria in Asian fermented foods, Microb. Cell Fact. (2011) S5, https://doi.org/10.1186/1475-2859-10-S1-S5. G. He, C. Wu, J. Huang, R. Zhou, Metabolic response of Tetragenococcus halophilus under salt stress, Biotechnol. Bioprocess Eng. 22 (2017) 366–375, https://doi.org/ 10.1007/s12257-017-0015-5. M.L. Chiang, H.C. Chen, C. Wu, M.J. Chen, Effect of acid adaptation on the environmental stress tolerance of three strains of Vibrio parahaemolyticus, Foodborne Pathog. Dis. 11 (2014) 287–294, https://doi.org/10.1089/fpd.2013.1641. J.L. Chen, M.L. Chiang, C.C. Chou, Ethanol and NaCl susceptibility and protein expression of acid-adapted B. Cereus 1-4-1 as well as its growth patterns in the presence of various carbon and nitrogen sources, Foodborne Pathog. Dis. 6 (2009) 453–460, https://doi.org/10.1089/fpd.2008.0231. R.A. Ortiz-Merino, N. Kuanyshev, K.P. Byrne, J.A. Varela, J.P. Morrissey, D. Porro, K.H. Wolfe, P. Branduardi, Transcriptional response to lactic acid stress in the hybrid yeast Zygosaccharomyces parabailii, Appl. Environ. Microbiol. 84 (2018) e02294–02217, https://doi.org/10.1128/AEM.02294-17. A. Hudecová, L. Valík, D. Liptáková, Quantification of Geotrichum candidum growth in co-culture with lactic acid bacteria, Czech J. Food Sci. 27 (2009) S218–S227, https://doi.org/10.17221/205/2009-CJFS. M. Mikulic‐Petkovsek, V. Schmitzer, A. Slatnar, F. Stampar, R. Veberic, Composition of sugars, organic acids, and total phenolics in 25 wild or cultivated berry species, J. Food Sci. 77 (2012) C1064–C1070, https://doi.org/10.1111/j. 1750-3841.2012.02896.x.

Process Biochemistry xxx (xxxx) xxx–xxx

S. Yao, et al.

[42] Z. Chi, Z.P. Wang, G.Y. Wang, I. Khan, Z.M. Chi, Microbial biosynthesis and secretion of l-malic acid and its applications, Crit. Rev. Biotechnol. 36 (2014) 99–107, https://doi.org/10.3109/07388551.2014.924474. [43] M. Tristezza, L.D. Feo, M. Tufariello, F. Grieco, V. Capozzi, G. Spano, G. Mita, F. Grieco, Simultaneous inoculation of yeasts and lactic acid bacteria: effects on fermentation dynamics and chemical composition of Negroamaro wine, LWT-Food Sci. Technol. 66 (2016) 406–412, https://doi.org/10.1016/j.lwt.2015.10.064. [44] L.M. Mendoza, M.C.M.D. Nadra, M.E. Farías, Antagonistic interaction between yeasts and lactic acid bacteria of oenological relevance: partial characterization of inhibitory compounds produced by yeasts, Food Res. Int. 43 (2010) 1990–1998, https://doi.org/10.1016/j.foodres.2010.05.017. [45] J. Zhang, C. Wu, G. Du, C. Jian, Enhanced acid tolerance in Lactobacillus casei by adaptive evolution and compared stress response during acid stress, Biotechnol. Bioprocess Eng. 17 (2012) 283–289, https://doi.org/10.1007/s12257-011-0346-6. [46] J.A.R. Bodman, Y. Yang, M.R. Logan, E. Gary, Yeast translation elongation factor1A binds vacuole-localized Rho1p to facilitate membrane integrity through F-actin remodeling, J. Biol. Chem. 290 (2015) 4705–4716, https://doi.org/10.1074/jbc. M114.630764. [47] L. Yu, J. Nie, C. Cao, Y. Jin, M. Yan, F. Wang, J. Liu, Y. Xiao, Y. Liang, W. Zhang, Phosphatidic acid mediates salt stress response by regulation of MPK6 in Arabidopsis thaliana, New Phytol. 188 (2010) 762–773, https://doi.org/10.2307/40927908. [48] N.M. Berterame, D. Porro, D. Ami, P. Branduardi, Protein aggregation and membrane lipid modifications under lactic acid stress in wild type and OPI1 deleted Saccharomyces cerevisiae strains, Microb. Cell Fact. 15 (2016) 39, https://doi.org/ 10.1186/s12934-016-0438-2. [49] W.K. Yang, C.H. Chung, H.C. Cheng, C.H. Tang, T.H. Lee, Different expression

[50]

[51]

[52]

[53] [54]

[55]

[56]

9

patterns of renal Na+/K+-ATPase α-isoform-like proteins between tilapia and milkfish following salinity challenges, Comp. Biochem. Physiol. B Biochem. Mol. Biol. 202 (2016) 23–30, https://doi.org/10.1016/j.cbpb.2016.07.008. J. Li, J. Wang, L. Yang, Y. Chen, Y. Zhou, Changes in plasma osmolality and Na + /K + ATPase activity of juvenile obscure puffer Takifugu obscurus following salinity challenge, Biochem. Syst. Ecol. 56 (2014) 111–117, https://doi.org/10.1016/j. bse.2014.05.006. B. Soufi, C.D. Kelstrup, G. Stoehr, F. Fröhlich, T.C. Walther, J.V. Olsen, Global analysis of the yeast osmotic stress response by quantitative proteomics, Mol. Biosyst. 5 (2009) 1337–1346, https://doi.org/10.1039/B902256B. M. Martinezpastor, M. Proft, A. Pascualahuir, Adaptive changes of the yeast mitochondrial proteome in response to salt stress, Omics 14 (2010) 541–552, https:// doi.org/10.1089/omi.2010.0020. C.E. Simpson, M.P. Ashe, Adaptation to stress in yeast: to translate or not? Biochem. Soc. Trans. 40 (2012) 794, https://doi.org/10.1042/bst20120078. O. Ponomarova, N. Gabrielli, D.C. Sévin, M. Mülleder, K. Zirngibl, K. Bulyha, S. Andrejev, E. Kafkia, A. Typas, U. Sauer, Yeast creates a niche for symbiotic lactic acid bacteria through nitrogen overflow, Cell Syst. 5 (2017) 345–357, https://doi. org/10.1016/j.cels.2017.09.002 e346. S. Xie, L. Tian, Y. Jin, H. Yang, G. Liang, Y. Liu, Effect of glycine supplementation on growth performance, body composition and salinity stress of juvenile Pacific white shrimp, Litopenaeus vannamei fed low fishmeal diet, Aquaculture 418-419 (2014) 159–164, https://doi.org/10.1016/j.aquaculture.2013.10.023. N. Beales, Adaptation of microorganisms to cold temperatures, weak acid preservatives, low ph, and osmotic stress: a review, Compr. Rev. Food Sci. Food Saf. 3 (2010) 1–20, https://doi.org/10.1111/j.1541-4337.2004.tb00057.x.