Search results for " fermentation"
showing 10 items of 283 documents
2-Oxoglutarate decarboxylase ofLeuconostoc oenos
1990
InLeuconostoc oenos, the typical organism of the malolactic fermentation of wine, a 2-oxoglutarate decarboxylase was detected. This inducible enzyme decarboxylates 2-oxoglutarate but not pyruvate. The resulting succinaldehydate is rapidly reduced to 4-hydroxybutyrate or oxidized to succinate in further reactions. 2-Oxoglutarate decarboxylase is thiamin-diphosphate-dependent; the pH optimum is at 5.3 and theK m value for 2-oxoglutarate is 1.8 mmol/L.
Influence of fatty acids on the growth of wine microorganisms Saccharomyces cerevisiae and Oenococcus oeni
1998
The effects of fatty acids, extracted during prefermentation grape skin-contact on Saccharomyces cerevisiae and Oenococcus oeni, were studied. The influence of skin-contact on total fatty acid content was evaluated both in Chardonnay must and in synthetic medium. Prior to alcoholic fermentation, the skin-contact contributes to a large enrichment of long-chain fatty acids (C 16 to C 18:3 ). These results induced a positive effect on yeast growth and particularly on cell viability. In the skin-contact fermented media, levels of C 12 and especially C 10 are lower and macromolecules content higher than in controls. This production of extracellular mannoproteins and the reduction of medium-chain…
Optimization of a Biotechnological Process for Production and Purification of Two Recombinant Proteins: Col G and Col H
2017
Different strategies can be used for increasing production of heterologous recombinant proteins in Escherichia coli. Protein size is often critical for obtaining the best quantity/quality ratio of recombinant protein expression. This study focuses on two recombinant proteins; Class I and class II Collagenases, namely Col G and Col H. Their size is about 150 kDa each. We have developed a method to obtain high levels of cell growth and intracellular expression of each Collagenases in recombinant E. coli BL21(DE3). Batch and Fed-batch fermentation procedures have been performed. Results show that Fed-batch technique was most effective in obtaining the highest cell density for each recombinant …
Lactic Acid Bacteria in Spanish Red Rose and White Musts and Wines under Cellar Conditions
1992
The dynamics of the lactic acid bacterial (LAB) population in different cellars, fermentation conditions and musts were analyzed. The number of LAB in fresh musts diminished quickly in the first few days, but an increase of these bacteria occurred during the later stages of the alcoholic fermentation. The species found in fresh musts were Lactobacillus plantarum, L. hilgardii, L. brevis, L. confusus, and Leuc. onostoc paramesenteroides. At the end of fermentation only L. hilgardii, Leuc. oenos and L. fructivorans were isolated. The API 50 CHL system was not useful to identify strains of Leuc. oenos species. All the isolated strains degraded malic acid in synthetic medium but only two strain…
Optimising Lactic Acid Cheese Packaging Systems
2016
On the basis of a previous research, it seems that foil-wrapped tray solutions are not particularly chosen by lactic acid cheese consumers. With relation to this study, almost half of the respondent population would have expressed the desire of different packages. Parchment packages and poly(ethylene-co-vinyl acetate)/polyvinylidene chloride/poly(ethylene-co-vinyl acetate) laminates would be removed by 25.0 and 12.5% of customers, respectively. Polyamide/polyethylene double and single packaging would be removed from the market only by 5.0% of respondents. Data have shown that cheese and packaging quality are dependent on lactic acid cheese surface microflora. The type of this microflora is …
Cultivation ofZymomonas mobilis 113 S at Different Mixing Regimes and their Influence on the Levan Formation
2001
The Zymomonas mobilis I 13 S strain was cultivated in a bioreactor with a working volume of 1.4 I at different stirring regimes in a 15% initial sucrose medium The levan obtained in the fermentation process was analyzed by gel filtration. Because the sucrose/biomass ratio in the fermentation broth decreased to below 300 g/g, the insufficient concentration of sucrose might have decreased the concentration of levan. Besides the growth characteristics of the population, the mixing intensity and flow structure were also found to influence the molecular mass of levan. At 600 rpm, the microorganisms produced levan with a molecular mass lower than at 300 rpm. The stirring of a fermentation broth w…
Solvent production from rice straw by a co-culture of Clostridium acetobutylicum and Saccharomyces cerevisiae: effect of pH control
2022
One of the challenges in biofuel production from lignocellulosic wastes is to improve its conversion to solvents; therefore, new strategies to enhance xylose uptake are required due to be the secondary abundant sugar. In this context, a novel fermentation strategy integrating a co-culture of Clostridium acetobutylicum and Saccharomyces cerevisiae with pH control was developed. Initially, two different buffers, ammonium acetate and calcium carbonate, were tested under pHmin > 4.8 by fermenting 60 g L−1 of glucose with the C. acetobutylicum monoculture. Ammonium acetate was selected for fermenting media as butanol production was increased from 9.8 to 10.9 g L−1 over the calcium carbonate test…
Evaluation of the enhanced resistance of Ogataea (Hansenula) polymorpha to benzalkonium chloride as a resource for bioremediation technologies
2019
Abstract Benzalkonium chloride (BAC) is highly abundant in wastewaters due to its wide application in household and industrial products. The aim of this research was to compare the resistance of two genetically related strains, Ogataea polymorpha (wild type) and O. polymorpha cat8Δ (recombinant strain), to enhanced concentrations of BAC (≥ 100 mg/L) in terms of its appearance in wastewaters. Inhibition of the respiration activity of wt and cat8Δ by 100 mg/L and 300 mg/L BAC in a xylose-containing broth (4 g/L xylose) was dependent on the carbon source used for obtaining the yeast biomass through ethanol fermentation. The respiration activity of wt in a liquid broth was inhibited by BAC, whi…
Differential Contribution of the Parental Genomes to a
2019
In European regions of cold climate, S. uvarum can replace S. cerevisiae in wine fermentations performed at low temperatures. S. uvarum is a cryotolerant yeast that produces more glycerol, less acetic acid and exhibits a better aroma profile. However, this species exhibits a poor ethanol tolerance compared with S. cerevisiae. In the present study, we obtained by rare mating (non-GMO strategy), and a subsequent sporulation, an interspecific S. cerevisiae × S. uvarum spore-derivative hybrid that improves or maintains a combination of parental traits of interest for the wine industry, such as good fermentation performance, increased ethanol tolerance, and high glycerol and aroma productions. G…
The influence of backslopping on lactic acid bacteria diversity in tarhana fermentation
2020
Tarhana is produced at batch systems in which the microbiota has changed accordingly to the microbial load from ingredients. In order to stabilize the microbiota, the effects of backslopping carried out under different temperature regimes (25 and 30 °C), pH (3.70 and 4.00) and inoculation rates (5, 10 and 15%) on lactic acid bacteria (LAB) diversity were determined in tarhana dough. LAB and Total Aerobic Mesophilic Bacteria (TAMB) numbers increased in all tarhana dough samples subjected to backslopping. Temperature and pH significantly affected the microbiological diversity of tarhana whereas the different inoculation rates did not. Tarhana dough showed complex tarhana microbiota following …