- Email: [email protected]
Effect of temperature and physiological state on the fatty acid composition of Pseudomonas aeruginosa
International Journal of Food Microbiology 55 (2000) 79–81 www.elsevier.nl / locate / ijfoodmicro
Short communication
Effect of temperature and physiological state on the fatty acid composition of Pseudomonas aeruginosa a, *, B. Heyd b , J.Y. Leveau a ´ ´ F. Dubois-Brissonnet a , C. Malgrange a , L. Guerin-Mechin a
´ ´ Departement de Microbiologie Industrielle, Ecole Nationale Superieure des Industries Alimentaires, 1 Av. des Olympiades, ´ , France 91744 Massy Cedex b ´ ´ ´ des Industries Alimentaires, 1 Av. des Olympiades, Departement de Genie Industriel Alimentaire, Ecole Nationale Superieure ´ , France 91744 Massy Cedex
Abstract The influence of temperature and physiological state on fatty acid profiles of cell membranes of a Gram-negative bacteria was studied in this work. It has been shown that fatty acid composition is largely modified by these two parameters. Lipids play an important role in the composition and the function of cell membranes. These modifications of membrane structures are very important to understand because of their consequences on cell viability. 2000 Elsevier Science B.V. All rights reserved. Keywords: Fatty acids; Temperature; Physiological state
1. Introduction
2. Materials and methods
The viability of micro-organisms is known to be dependent upon cell membrane integrity. For Gramnegative bacteria, lipids play an important role in the structure and the function of cell membranes. Our aim is to study the influence of temperature and physiological state on fatty acids profiles of cell membranes.
The bacterial strain used in this study is Pseudomonas aeruginosa ATTC 15442. The effect of temperature and physiological state on fatty acid composition of cells was studied in combination using a D-optimal experimental design. Temperature (T ) ranged from 9.5 to 42.58C. Physiological states ( r ) are denominated on a 1–5 scale on the growth curve (Fig. 1). Statistical examination of the results and a response surface study were carried out by Matlab software (version 4.2c.1, the Math Works, USA). Polynomial models of the form Y 5 a 0 1 a 1 T 1 a 2 r 1 a 3 T 2 1 a 4 r 2 1 a 5 Tr were obtained and represented as two-dimensional graphs. Extraction and methylation of fatty acids were
*Corresponding author. Tel.: 133-1-6993-5054. ´ ´ E-mail address: [email protected] (L. Guerin-Mechin)
0168-1605 / 00 / $ – see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S0168-1605( 00 )00198-7
80
F. Dubois-Brissonnet et al. / International Journal of Food Microbiology 55 (2000) 79 – 81
Fig. 1. Scale of physiological state (from 1 to 5) on a growth curve of Pseudomonas aeruginosa at 378C.
Fig. 2. Evolution of saturated fatty acids and unsaturated fatty acids when temperature vary, for cells harvested in middle exponential phase.
carried out using the method of Moss (1981) with the modifications introduced by Miller and Berger (1985). Fatty acid methyl esters were then separated by gas chromatography. Extractions were made in duplicate.
3. Results and discussion Fourteen fatty acids were detected. Among these, laurate (C12:0), 3-hydroxydecanoate (3-OH C10:0), 2- and 3-hydroxydodecanoate (2-OH C12:0 and 3OH C12:0) are specific fatty acids of lipid A (Kropinski et al., 1987). Myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1 cis9), palmitelaidic acid (C16:1 trans9), stearic acid (C18:0), cis-vaccenic acid (C18:1 cis11), trans-vaccenic acid (C18:1 trans11), lactobacillic acid (C19cycl.11,12) and cis-9,10-methylene-hexadecanoic acid (C17cycl.9,10) were the other identified fatty acids. Total saturated fatty acids (SFA) and total unsaturated fatty acids (UFA) were highly influenced by temperature. When temperature increased from 15 to 408C, SFA increased from 25 to 39% in cells harvested in middle exponential phase while UFA decreased from 66.5 to 51% (Fig. 2). As an example of SFA, the evolution of C12:0 fatty acid when temperature and physiological state varied is represented in Fig. 3. C12:0 proportion increased when temperature increased and, when temperature was higher than 208C, C12:0 increased when cells moved from early to late exponential (Fig. 3).
Fig. 3. Evolution of lauric acid proportions when temperature and physiological state varied.
As it has been observed for some other microorganisms, the saturation of membrane phospholipids in Pseudomonas aeruginosa when growth temperature increased seems to be a mean of maintaining a constant and optimal lipid fluidity of membrane. These changes are referred to as the homeoviscous adaptation (Russell and Fukunaga, 1990). The increase of C12:0 proportion when temperature increases showed that the lipid A was also modified in response to temperature. Kropinski et al. (1987) noticed a similar evolution. The changes observed during the transition period from late exponential phase to stationary phase seemed to be a way of conserving energy by reducing membrane fluidity (MacGarrity and Armstrong, 1975).
F. Dubois-Brissonnet et al. / International Journal of Food Microbiology 55 (2000) 79 – 81
References Kropinski, A.M.B., Lewis, V., Berry, D., 1987. Effect of growth temperature on the lipids, outer membrane proteins, and lipopolysaccharides of Pseudomonas aeruginosa PAO. J. Bacteriol. 169, 1960–1966. MacGarrity, J.T., Armstrong, J.B., 1975. The effect of salt on phospholipid fatty composition in Escherichia coli K-12. Biochim. Biophys. Acta 398, 258–264.
81
Miller, L., Berger, T., 1985. Bacteria identification by gas chromatography of whole cell fatty acids. Application note 228-41, Hewlett-Packard. Moss, C.W., 1981. Gas–liquid chromatography as an analytical tool in microbiology. J. Chromatogr. 203, 337–347. Russell, N.J., Fukunaga, N., 1990. A comparison of thermal adaptation of membrane lipids in psychrophilic and thermophilic bacteria. FEMS Microbiol. Rev. 75, 171–182.
Short communication
Effect of temperature and physiological state on the fatty acid composition of Pseudomonas aeruginosa a, *, B. Heyd b , J.Y. Leveau a ´ ´ F. Dubois-Brissonnet a , C. Malgrange a , L. Guerin-Mechin a
´ ´ Departement de Microbiologie Industrielle, Ecole Nationale Superieure des Industries Alimentaires, 1 Av. des Olympiades, ´ , France 91744 Massy Cedex b ´ ´ ´ des Industries Alimentaires, 1 Av. des Olympiades, Departement de Genie Industriel Alimentaire, Ecole Nationale Superieure ´ , France 91744 Massy Cedex
Abstract The influence of temperature and physiological state on fatty acid profiles of cell membranes of a Gram-negative bacteria was studied in this work. It has been shown that fatty acid composition is largely modified by these two parameters. Lipids play an important role in the composition and the function of cell membranes. These modifications of membrane structures are very important to understand because of their consequences on cell viability. 2000 Elsevier Science B.V. All rights reserved. Keywords: Fatty acids; Temperature; Physiological state
1. Introduction
2. Materials and methods
The viability of micro-organisms is known to be dependent upon cell membrane integrity. For Gramnegative bacteria, lipids play an important role in the structure and the function of cell membranes. Our aim is to study the influence of temperature and physiological state on fatty acids profiles of cell membranes.
The bacterial strain used in this study is Pseudomonas aeruginosa ATTC 15442. The effect of temperature and physiological state on fatty acid composition of cells was studied in combination using a D-optimal experimental design. Temperature (T ) ranged from 9.5 to 42.58C. Physiological states ( r ) are denominated on a 1–5 scale on the growth curve (Fig. 1). Statistical examination of the results and a response surface study were carried out by Matlab software (version 4.2c.1, the Math Works, USA). Polynomial models of the form Y 5 a 0 1 a 1 T 1 a 2 r 1 a 3 T 2 1 a 4 r 2 1 a 5 Tr were obtained and represented as two-dimensional graphs. Extraction and methylation of fatty acids were
*Corresponding author. Tel.: 133-1-6993-5054. ´ ´ E-mail address: [email protected] (L. Guerin-Mechin)
0168-1605 / 00 / $ – see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S0168-1605( 00 )00198-7
80
F. Dubois-Brissonnet et al. / International Journal of Food Microbiology 55 (2000) 79 – 81
Fig. 1. Scale of physiological state (from 1 to 5) on a growth curve of Pseudomonas aeruginosa at 378C.
Fig. 2. Evolution of saturated fatty acids and unsaturated fatty acids when temperature vary, for cells harvested in middle exponential phase.
carried out using the method of Moss (1981) with the modifications introduced by Miller and Berger (1985). Fatty acid methyl esters were then separated by gas chromatography. Extractions were made in duplicate.
3. Results and discussion Fourteen fatty acids were detected. Among these, laurate (C12:0), 3-hydroxydecanoate (3-OH C10:0), 2- and 3-hydroxydodecanoate (2-OH C12:0 and 3OH C12:0) are specific fatty acids of lipid A (Kropinski et al., 1987). Myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1 cis9), palmitelaidic acid (C16:1 trans9), stearic acid (C18:0), cis-vaccenic acid (C18:1 cis11), trans-vaccenic acid (C18:1 trans11), lactobacillic acid (C19cycl.11,12) and cis-9,10-methylene-hexadecanoic acid (C17cycl.9,10) were the other identified fatty acids. Total saturated fatty acids (SFA) and total unsaturated fatty acids (UFA) were highly influenced by temperature. When temperature increased from 15 to 408C, SFA increased from 25 to 39% in cells harvested in middle exponential phase while UFA decreased from 66.5 to 51% (Fig. 2). As an example of SFA, the evolution of C12:0 fatty acid when temperature and physiological state varied is represented in Fig. 3. C12:0 proportion increased when temperature increased and, when temperature was higher than 208C, C12:0 increased when cells moved from early to late exponential (Fig. 3).
Fig. 3. Evolution of lauric acid proportions when temperature and physiological state varied.
As it has been observed for some other microorganisms, the saturation of membrane phospholipids in Pseudomonas aeruginosa when growth temperature increased seems to be a mean of maintaining a constant and optimal lipid fluidity of membrane. These changes are referred to as the homeoviscous adaptation (Russell and Fukunaga, 1990). The increase of C12:0 proportion when temperature increases showed that the lipid A was also modified in response to temperature. Kropinski et al. (1987) noticed a similar evolution. The changes observed during the transition period from late exponential phase to stationary phase seemed to be a way of conserving energy by reducing membrane fluidity (MacGarrity and Armstrong, 1975).
F. Dubois-Brissonnet et al. / International Journal of Food Microbiology 55 (2000) 79 – 81
References Kropinski, A.M.B., Lewis, V., Berry, D., 1987. Effect of growth temperature on the lipids, outer membrane proteins, and lipopolysaccharides of Pseudomonas aeruginosa PAO. J. Bacteriol. 169, 1960–1966. MacGarrity, J.T., Armstrong, J.B., 1975. The effect of salt on phospholipid fatty composition in Escherichia coli K-12. Biochim. Biophys. Acta 398, 258–264.
81
Miller, L., Berger, T., 1985. Bacteria identification by gas chromatography of whole cell fatty acids. Application note 228-41, Hewlett-Packard. Moss, C.W., 1981. Gas–liquid chromatography as an analytical tool in microbiology. J. Chromatogr. 203, 337–347. Russell, N.J., Fukunaga, N., 1990. A comparison of thermal adaptation of membrane lipids in psychrophilic and thermophilic bacteria. FEMS Microbiol. Rev. 75, 171–182.