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Investigation of PHAs production from acidified olive oil mill wastewater (OOMW) by pure cultures of Pseudomonas spp. strains
New Biotechnology · Volume 25S · September 2009
3.1.58
3.1.59
Pre-treatment of wheat straw, hay and poplar using diluted sulphuric acid and sodium hydroxide at low temperatures for the production of bioethanol
Investigation of PHAs production from acidified olive oil mill wastewater (OOMW) by pure cultures of Pseudomonas spp. strains
S. Deprez ∗ , A. Verplaetse, G. Aerts
C. Kourmentza ∗ , E. Mitova, N. Stoyanova, I. Ntaikou, M. Kornaros
KaHo Sint-Lieven, Ghent, Belgium
University of Patras, Patras, Greece
Lignocellulosic biomass (such as agricultural residues, grasses, organic waste streams and remainders from paper and wood industry) has many potential advantages for the production of bioethanol because they are widely available, relative inexpensive and non-competitive with food crops. A major disadvantage of using lignocellulose for ethanol fermentations is the requirement of a costly pre-treatment step to facilitate the hydrolysis of carbohydrate polymers into fermentable sugars. Ethanol yield will vary considerably using different feedstocks, although they have approximately the same composition and similar pre-treatment conditions are applied. In this study the feasibility of different pre-treatment methods using a minimal amount of chemical reagents and application of low temperatures and pressures was investigated, to keep energy costs, the impact on the environment and the production of growth inhibiting compounds as low as possible. The use of diluted sulphuric acid or sodium hydroxide at different temperatures, reaction times and concentrations were examined to identify the conditions which provide the highest xylan to xylose conversion and the best cellulose to glucose conversion during subsequent enzymatic hydrolysis in combination with a minimal amount of fermentation inhibiting compounds. The diversity of the yield dependent on the type of feedstock was evaluated using wheat straw, hay and poplar as raw material. Grinded wheat straw, hay or poplar (5% W/V) was suspended in various diluted sulphuric acid or sodium hydroxide solutions (0.1—0.4 M) and heated using different temperature—time combinations (25◦ C/20 hours—60◦ C/4 hours—100◦ C/4 hours). Subsequently the water insoluble fraction was filtrated and washed out with water. The residue was enzymatically hydrolyzed using a cellulase complex (NS50013) and a -glucosidase (NS50010) provided by Novozymes. After each hydrolysis step the water insoluble fraction was analyzed for the total amount of dry solids. The liquid fraction was analyzed before and after total hydrolysis regarding their content of monomeric and oligomeric sugars using high performance liquid chromatography. Also the amount of furfural and hydroxymethylfurfural was determined. In addition fermentation with Saccharomyces cerevisiae was performed on the filtrate to study the toxicity of the chemical hydrolysates. Using diluted sulphuric acid a high conversion of hemicellulose and cellulose is obtained at 100◦ C. The application of diluted sodium hydroxide gives the highest yield of monomeric sugars utilizing room temperature. Increasing temperatures with sodium hydroxide leads to loss of carbohydrates and increase of inhibitor concentrations.
The aim of the present study is to investigate the feasibility of exploiting olive oil mill wastewater (OOMW) for PHAs production by pure culture of Pseudomonas sp. Four different strains belonging to the Pseudomonas genus were isolated from an ‘enriched’ mixed culture that was developed using activated sludge from the municipal wastewater treatment plant of the city of Patras (Greece) as inoculum. The enrichment was performed by subjecting the culture to sequential cycles of carbon and nitrogen limitation to ensure that the predominant strains would be PHAs forming bacteria. To estimate the maximum capacity of PHAs production under favorable conditions, batch experiments were carried out under nitrogen limitation and continuous aeration using synthetic substrate with volatile fatty acids (VFAs) that is acetate, propionate, butyrate as carbon source with both mixed culture as well as all isolates. It was shown that the mixed culture had the best performance as far as PHAs yield is concerned (g PHAs produced/g VFAs consumed) whereas in terms of final PHAs content (g PHAs/g of cell dry mass) one of the four isolates proved to be more efficient. It is also noticeable that although butyrate was preferably consumed from the mixed culture all isolates tested tended to consume acids of smaller molecular weight first, thus indicating that the mixed culture comprises from other microorganisms too. To comparatively evaluate the behavior of the mixed and pure cultures when instead of synthetic substrate a real waste is supplied as feedstock for PHAs production, batch experiments with acidified OOMW were conducted. The acidification of OOMW was accomplished via anaerobic fermentation using a mesophilic (35◦ C) CSTR-type bioreactor. The effluent of the reactor (acidified OOMW) which was rich in VFAs was filtered and sterilized to be used as substrate for PHAs production under nitrogen limitation and continuous aeration. As expected, the behavior of the cultures was the same in all cases in terms of substrate preference. The achieved yields though were lower compared to the respective ones when synthetic substrate was used, which could be attributed to the complexity of the wastewater or to inhibitory effect of ‘toxic’ compounds present in OOMW, such as polyphenols. doi:10.1016/j.nbt.2009.06.604
doi:10.1016/j.nbt.2009.06.603
www.elsevier.com/locate/nbt S269
3.1.58
3.1.59
Pre-treatment of wheat straw, hay and poplar using diluted sulphuric acid and sodium hydroxide at low temperatures for the production of bioethanol
Investigation of PHAs production from acidified olive oil mill wastewater (OOMW) by pure cultures of Pseudomonas spp. strains
S. Deprez ∗ , A. Verplaetse, G. Aerts
C. Kourmentza ∗ , E. Mitova, N. Stoyanova, I. Ntaikou, M. Kornaros
KaHo Sint-Lieven, Ghent, Belgium
University of Patras, Patras, Greece
Lignocellulosic biomass (such as agricultural residues, grasses, organic waste streams and remainders from paper and wood industry) has many potential advantages for the production of bioethanol because they are widely available, relative inexpensive and non-competitive with food crops. A major disadvantage of using lignocellulose for ethanol fermentations is the requirement of a costly pre-treatment step to facilitate the hydrolysis of carbohydrate polymers into fermentable sugars. Ethanol yield will vary considerably using different feedstocks, although they have approximately the same composition and similar pre-treatment conditions are applied. In this study the feasibility of different pre-treatment methods using a minimal amount of chemical reagents and application of low temperatures and pressures was investigated, to keep energy costs, the impact on the environment and the production of growth inhibiting compounds as low as possible. The use of diluted sulphuric acid or sodium hydroxide at different temperatures, reaction times and concentrations were examined to identify the conditions which provide the highest xylan to xylose conversion and the best cellulose to glucose conversion during subsequent enzymatic hydrolysis in combination with a minimal amount of fermentation inhibiting compounds. The diversity of the yield dependent on the type of feedstock was evaluated using wheat straw, hay and poplar as raw material. Grinded wheat straw, hay or poplar (5% W/V) was suspended in various diluted sulphuric acid or sodium hydroxide solutions (0.1—0.4 M) and heated using different temperature—time combinations (25◦ C/20 hours—60◦ C/4 hours—100◦ C/4 hours). Subsequently the water insoluble fraction was filtrated and washed out with water. The residue was enzymatically hydrolyzed using a cellulase complex (NS50013) and a -glucosidase (NS50010) provided by Novozymes. After each hydrolysis step the water insoluble fraction was analyzed for the total amount of dry solids. The liquid fraction was analyzed before and after total hydrolysis regarding their content of monomeric and oligomeric sugars using high performance liquid chromatography. Also the amount of furfural and hydroxymethylfurfural was determined. In addition fermentation with Saccharomyces cerevisiae was performed on the filtrate to study the toxicity of the chemical hydrolysates. Using diluted sulphuric acid a high conversion of hemicellulose and cellulose is obtained at 100◦ C. The application of diluted sodium hydroxide gives the highest yield of monomeric sugars utilizing room temperature. Increasing temperatures with sodium hydroxide leads to loss of carbohydrates and increase of inhibitor concentrations.
The aim of the present study is to investigate the feasibility of exploiting olive oil mill wastewater (OOMW) for PHAs production by pure culture of Pseudomonas sp. Four different strains belonging to the Pseudomonas genus were isolated from an ‘enriched’ mixed culture that was developed using activated sludge from the municipal wastewater treatment plant of the city of Patras (Greece) as inoculum. The enrichment was performed by subjecting the culture to sequential cycles of carbon and nitrogen limitation to ensure that the predominant strains would be PHAs forming bacteria. To estimate the maximum capacity of PHAs production under favorable conditions, batch experiments were carried out under nitrogen limitation and continuous aeration using synthetic substrate with volatile fatty acids (VFAs) that is acetate, propionate, butyrate as carbon source with both mixed culture as well as all isolates. It was shown that the mixed culture had the best performance as far as PHAs yield is concerned (g PHAs produced/g VFAs consumed) whereas in terms of final PHAs content (g PHAs/g of cell dry mass) one of the four isolates proved to be more efficient. It is also noticeable that although butyrate was preferably consumed from the mixed culture all isolates tested tended to consume acids of smaller molecular weight first, thus indicating that the mixed culture comprises from other microorganisms too. To comparatively evaluate the behavior of the mixed and pure cultures when instead of synthetic substrate a real waste is supplied as feedstock for PHAs production, batch experiments with acidified OOMW were conducted. The acidification of OOMW was accomplished via anaerobic fermentation using a mesophilic (35◦ C) CSTR-type bioreactor. The effluent of the reactor (acidified OOMW) which was rich in VFAs was filtered and sterilized to be used as substrate for PHAs production under nitrogen limitation and continuous aeration. As expected, the behavior of the cultures was the same in all cases in terms of substrate preference. The achieved yields though were lower compared to the respective ones when synthetic substrate was used, which could be attributed to the complexity of the wastewater or to inhibitory effect of ‘toxic’ compounds present in OOMW, such as polyphenols. doi:10.1016/j.nbt.2009.06.604
doi:10.1016/j.nbt.2009.06.603
www.elsevier.com/locate/nbt S269