The Experts below are selected from a list of 5847282 Experts worldwide ranked by ideXlab platform
Shang-tian Yang - One of the best experts on this subject based on the ideXlab platform.
-
improved production of 2 3 butanediol in bacillus amyloliquefaciens by over expression of glyceraldehyde 3 phosphate dehydrogenase and 2 3 butanediol dehydrogenase
PLOS ONE, 2013Co-Authors: Taowei Yang, Zhiming Rao, Xian Zhang, Shang-tian YangAbstract:Background Previously, a safe strain, Bacillus amyloliquefaciens B10-127 was identified as an excellent candidate for industrial-scale microbial fermentation of 2,3-butanediol (2,3-BD). However, B. amyloliquefaciens fermentation yields large quantities of acetoin, lactate and succinate as by-products, and the 2,3-BD yield remains prohibitively low for commercial production. Methodology/Principal Findings In the 2,3-butanediol metabolic pathway, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) catalyzes the conversion of 3-phosphate glyceraldehyde to 1,3-bisphosphoglycerate, with concomitant reduction of NAD+ to NADH. In the same pathway, 2,3-BD dehydrogenase (BDH) catalyzes the conversion of acetoin to 2,3-BD with concomitant oxidation of NADH to NAD+. In this study, to improve 2,3-BD production, we first over-produced NAD+-dependent GAPDH and NADH-dependent BDH in B. amyloliquefaciens. Excess GAPDH reduced the fermentation time, increased the 2,3-BD yield by 12.7%, and decreased the acetoin titer by 44.3%. However, the process also enhanced lactate and succinate production. Excess BDH increased the 2,3-BD yield by 16.6% while decreasing acetoin, lactate and succinate production, but prolonged the fermentation time. When BDH and GAPDH were co-overproduced in B. amyloliquefaciens, the fermentation time was reduced. Furthermore, in the NADH-dependent pathways, the molar yield of 2,3-BD was increased by 22.7%, while those of acetoin, lactate and succinate were reduced by 80.8%, 33.3% and 39.5%, relative to the parent strain. In fed-batch fermentations, the 2,3-BD concentration was maximized at 132.9 g/l after 45 h, with a productivity of 2.95 g/l·h. Conclusions/Significance Co-overexpression of bdh and gapA genes proved an effective method for enhancing 2,3-BD production and inhibiting the accumulation of unwanted by-products (acetoin, lactate and succinate). To our knowledge, we have attained the highest 2,3-BD fermentation yield thus far reported for safe microorganisms.
-
production of carboxylic acids from hydrolyzed corn meal by immobilized cell fermentation in a fibrous bed bioreactor
Bioresource Technology, 2002Co-Authors: Yu Liang Huang, Likun Zhang, Chun Ming Cheung, Shang-tian YangAbstract:Abstract Corn meal hydrolyzed with amylases was used as the carbon source for producing acetic, propionic, and butyric acids via anaerobic fermentations. In this study, corn meal, containing 75% (w/w) starch, 20% (w/w) fibers, and 1.5% (w/w) protein, was first hydrolyzed using amylases at 60 °C. The hydrolysis yielded approximately 100% recovery of starch converted to glucose and 17.9% recovery of protein. The resulting corn meal hydrolyzate was then used, after sterilization, for fermentation studies. A co-culture of Lactococcus lactis and Clostridium formicoaceticum was used to produce acetic acid from glucose. Propionibacterium acidipropionici was used for propionic acid fermentation, and Clostridium tyrobutylicum was used for butyric acid production. These cells were immobilized on a spirally wound fibrous matrix packed in a fibrous-bed bioreactor (FBB) developed for multi-phase biological reactions or fermentation. The bioreactor was connected to a stirred-tank fermentor that provided pH and temperature controls via medium circulation. The fermentation system was operated at the recycle batch mode. Temperature and pH were controlled at 37 °C and 7.6, respectively, for acetic acid fermentation, 32 °C and 6.0, respectively, for propionic acid fermentation, and 37 °C and 6.0, respectively, for butyric acid production. The fermentation demonstrated a yield of approximately 100% and a volumetric productivity of approximately 1 g/(l h) for acetic acid production. The propionic acid fermentation achieved an approximately 60% yield and a productivity of 2.12 g/(l h), whereas the butyric acid fermentation obtained an approximately 50% yield and a productivity of 6.78 g/(l h). These results were comparable to, or better than those fermentations using chemically defined media containing glucose as the substrate, suggesting that these carboxylic acids can be efficiently produced from direct fermentation of corn meal hydrolyzate. The corn fiber present as suspended solids in the corn meal hydrolyzate did not cause operating problem to the immobilized cell bioreactor as is usually encountered by conventional immobilized cell bioreactor systems. It is concluded that the FBB technology is suitable for producing value-added biochemicals directly from agricultural residues or commodities such as corn meal.
-
acetate production from whey lactose using co immobilized cells of homolactic and homoacetic bacteria in a fibrous bed bioreactor
Biotechnology and Bioengineering, 1998Co-Authors: Yan Huang, Shang-tian YangAbstract:Acetate was produced from whey lactose in batch and fed-batch fermentations using co-immobilized cells of Clostridium formicoaceticum and Lactococcus lactis. The cells were immobilized in a spirally wound fibrous sheet packed in a 0.45-L column reactor, with liquid circulated through a 5-L stirred-tank fermentor. Industrial-grade nitrogen sources, including corn steep liquor, casein hydrolysate, and yeast hydrolysate, were studied as inexpensive nutrient supplements to whey permeate and acid whey. Supplementation with either 2.5% (v/v) corn steep liquor or 1.5 g/L casein hydrolysate was adequate for the cocultured fermentation. The overall acetic acid yield from lactose was 0.9 g/g, and the productivity was 0.25 g/(L h). Both lactate and acetate at high concentrations inhibited the homoacetic fermentation. To overcome these inhibitions, fed-batch fermentations were used to keep lactate concentration low and to adapt cells to high-concentration acetate. The final acetate concentration obtained in the fed-batch fermentations were used to keep lactate concentration low and to adapt cells to high-concentration acetate. The final acetate concentration obtained in the fed-batch fermentation was 75 g/L, which was the highest acetate concentration ever produced by C. formicoaceticum. Even at this high acetate concentration, the overall productivity was 0.18 g/(L h) based on the total medium volumemore » and 1.23 g/(L h) based on the fibrous-bed reactor volume. The cells isolated from the fibrous-bed bioreactor at the end of this study were more tolerant to acetic acid than the original culture used to seed the bioreactor, indicating that adaptation and natural selection of acetate-tolerant strains occurred. This cocultured fermentation process could be used to produce a low-cost acetate deicer from whey permeate and acid whey.« less
Luca Simone Cocolin - One of the best experts on this subject based on the ideXlab platform.
-
impact of saccharomyces cerevisiae strain selection on malolactic fermentation by lactobacillus plantarum and oenococcus oeni
American Journal of Enology and Viticulture, 2020Co-Authors: Vasileios Englezos, Kalliopi Rantsiou, Fabrizio Torchio, Paola Vagnoli, Sibylle Kriegerweber, Luca Simone CocolinAbstract:Simultaneous inoculation of yeast and lactic acid bacteria (LAB) is considered a state-of-the-art strategy to reduce overall vinification time and improve microbiological stability of wines. This inoculation protocol sparked interest in selecting yeast and LAB strains to modulate malic acid consumption rate and wine composition. The study presented here addresses the impact on malic acid consumption and metabolite production of combining Saccharomyces cerevisiae strains with different fermentation rates and nutrition demands with Lactobacillus plantarum and Oenococcus oeni strains. S. cerevisiae strains in pure culture fermentations without LAB inoculation exhibited different patterns of malic acid consumption rate and metabolite production. Simultaneous S. cerevisiae and LAB inoculation influenced the kinetics of lactic acid production and titratable acidity in a LAB-strain dependent manner. Wines undergoing malolactic fermentation with L. plantarum ML Prime finished faster and contained more L-lactic acid than similar wines inoculated with O. oeni Lalvin VP41; however, the degree of acidification depended on the S. cerevisiae strain used to conduct alcoholic fermentation. This study reveals new knowledge about the use of L. plantarum in winemaking and shows the effect of S. cerevisiae strains with different enological characteristics, with or without LAB co-inoculation, on wine composition.
-
oxygen availability and strain combination modulate yeast growth dynamics in mixed culture fermentations of grape must with starmerella bacillaris and saccharomyces cerevisiae
Food Microbiology, 2018Co-Authors: Vasileios Englezos, Luca Giorgio Carlo Rolle, Kalliopi Rantsiou, Fabrizio Torchio, Francesco Cravero, Anne Ortizjulien, Milena Lambri, Vincenzo Gerbi, Luca Simone CocolinAbstract:Abstract Starmerella bacillaris (synonym Candida zemplinina ) is a non- Saccharomyces yeast that has been proposed as a co-inoculant of selected Saccharomyces cerevisiae strains in mixed culture fermentations to enhance the analytical composition of the wines. In order to acquire further knowledge on the metabolic interactions between these two species, in this study we investigated the impact of oxygen addition and combination of Starm. bacillaris with S. cerevisiae strains on the microbial growth and metabolite production. Fermentations were carried out under two different conditions of oxygen availability. Oxygen availability and strain combination clearly influenced the population dynamics throughout the fermentation. Oxygen concentration increased the survival time of Starm. bacillaris and decreased the growth rate of S. cerevisiae strains in mixed culture fermentations, whereas it did not affect the growth of the latter in pure culture fermentations. This study reveals new knowledge about the influence of oxygen availability on the successional evolution of yeast species during wine fermentation.
-
investigation of the dominance behavior of saccharomyces cerevisiae strains during wine fermentation
International Journal of Food Microbiology, 2013Co-Authors: Benedetta Perrone, Simone Giacosa, Luca Giorgio Carlo Rolle, Luca Simone Cocolin, Kalliopi RantsiouAbstract:Abstract During wine fermentation, different strains of Saccharomyces cerevisiae compete in the same fermenting must and dominance takes place when one strain overcomes all the others. The purpose of this study was to investigate this phenomenon by identifying S. cerevisiae strains endowed with this feature and to test them in laboratory fermentations. First, autochthonous S. cerevisiae from Nebbiolo fermentations were isolated, molecularly identified and characterized. Genetically diverse S. cerevisiae strains were subsequently subjected to physiological characterization and to micro-scale fermentation, the weight loss kinetics was measured and HPLC analysis was performed at the end of the fermentation. Then, the strains that presented good fermentation characteristics were chosen for further analysis and to determine the dominance feature. For this purpose, couples of strains were co-inoculated in Nebbiolo must and the fermentations were monitored by microbiological and chemical analysis. Two different inoculation approaches were used: Co-Fermentations in flasks with mixed cells and reactor Co-Fermentations, in which the cells from the two different strains were kept separate by means of a 0.45 μm filter membrane, which allowed the fermenting must to move freely between the two compartments. During the flask Co-Fermentations, a minisatellite PCR protocol was applied, in order to differentiate the two strains and determine which one was able to dominate. The protocol included a culture-dependent approach and an independent one. In the first case, DNA extraction was performed on all the colonies scraped off the plates after sampling. In the second case, DNA extraction was performed directly on the fermenting must. The strains that were able to dominate were tested against several S. cerevisiae in order to confirm this dominance behavior. Dominance was observed in the early stages of fermentation, as early as 3 days. Combinations of dominant and not-dominant strains were subjected to further tests in a Co-Fermentation reactor system, in order to perform single-strain analysis so as to obtain a better understanding of the dominance behavior. Surprisingly, the results obtained in the flask Co-Fermentations were not confirmed. In fact, the two strains, one which was hypothesized to be dominant and the other not-dominant, coexisted throughout the fermentation period. The results of this study suggest that the dominant behavior of S. cerevisiae is only expressed when they sense other yeasts in the same environment.
Raymond L. Huhnke - One of the best experts on this subject based on the ideXlab platform.
-
ethanol production during semi continuous syngas fermentation in a trickle bed reactor using clostridium ragsdalei
Bioresource Technology, 2016Co-Authors: Mamatha Devarapalli, Hasan K. Atiyeh, John R Phillips, Randy S Lewis, Raymond L. HuhnkeAbstract:An efficient syngas fermentation bioreactor provides a mass transfer capability that matches the intrinsic kinetics of the microorganism to obtain high gas conversion efficiency and productivity. In this study, mass transfer and gas utilization efficiencies of a trickle bed reactor during syngas fermentation by Clostridium ragsdalei were evaluated at various gas and liquid flow rates. Fermentations were performed using a syngas mixture of 38% CO, 28.5% CO2, 28.5% H2 and 5% N2, by volume. Results showed that increasing the gas flow rate from 2.3 to 4.6sccm increased the CO uptake rate by 76% and decreased the H2 uptake rate by 51% up to Run R6. Biofilm formation after R6 increased cells activity with over threefold increase in H2 uptake rate. At 1662h, the final ethanol and acetic acid concentrations were 5.7 and 12.3g/L, respectively, at 200ml/min of liquid flow rate and 4.6sccm gas flow rate.
-
Butanol and hexanol production in Clostridium carboxidivorans syngas fermentation: Medium development and culture techniques
Bioresource Technology, 2015Co-Authors: J R Phillips, Juan R. Torres, Jyotisna Saxena, Hasan K. Atiyeh, Mark R. Wilkins, Ralph S. Tanner, Raymond L. HuhnkeAbstract:Clostridium carboxidivorans was grown on model syngas (CO:H2:CO2 [70:20:10]) in a defined nutrient medium with concentrations of nitrogen, phosphate and trace metals formulated to enhance production of higher alcohols. C. carboxidivorans was successfully grown in a limited defined medium (no yeast extract, no MES buffer and minimal complex chemical inputs) using an improved fermentation protocol. Low partial pressure of CO in the headspace, coupled with restricted mass transfer for CO and H2, was required for successful fermentation. In the absence of substrate inhibition (particularly from CO), growth limitation increased production of alcohols, especially butanol and hexanol. Concentrations of butanol (over 1.0g/L), hexanol (up to 1.0g/L) and ethanol (over 3.0g/L) were achieved in bottle fermentations. Minimal medium and controlled supply of CO and H2 should be used in characterizing candidate butanol and hexanol producing strains to select for commercial potential.
-
ethanol production from syngas by clostridium strain p11 using corn steep liquor as a nutrient replacement to yeast extract
Bioresource Technology, 2011Co-Authors: Prasanth Maddipati, Hasan K. Atiyeh, Danielle D Bellmer, Raymond L. HuhnkeAbstract:Abstract The feasibility of replacing yeast extract (YE) by corn steep liquor (CSL), a low cost nutrient source, for syngas fermentation to produce ethanol using Clostridium strain P11 was investigated. About 32% more ethanol (1.7 g L−1) was produced with 20 g L−1 CSL media in 250-mL bottle fermentations compared to media with 1 g L−1 YE after 360 h. Maximum ethanol concentrations after 360 h of fermentation in a 7.5-L fermentor with 10 and 20 g L−1 CSL media were 8.6 and 9.6 g L−1, respectively, which represent 57% and 60% of the theoretical ethanol yields from CO. Only about 6.1 g L−1 of ethanol was obtained in the medium with 1 g L−1 YE after 360 h, which represents 53% of the theoretical ethanol yield from CO. The use of CSL also enhanced butanol production by sevenfold compared to YE in bottle fermentations. These results demonstrate that CSL can replace YE as the primary medium component and significantly enhance ethanol production by Clostridium strain P11.
Leigh I Francis - One of the best experts on this subject based on the ideXlab platform.
-
the effect of multiple yeasts co inoculations on sauvignon blanc wine aroma composition sensory properties and consumer preference
Food Chemistry, 2010Co-Authors: Ellena S King, Robyn L Kievit, Chris Curtin, Jan H Swiegers, Isak S Pretorius, Susan E P Bastian, Leigh I FrancisAbstract:Abstract Consumer acceptance testing has been only recently applied in wine research, to assess wine sensory attributes that affect hedonic liking. The aim of this study was to investigate the effect of Saccharomyces yeast co-inoculations on wine volatile composition and sensory profiles, and to determine if differences were sufficient enough to affect consumer acceptance. Fermentations were conducted using two- and three-yeast co-inoculations, and single strains. Yeast inocula differed substantially in volatile thiols and other flavour compounds, and in their sensory properties. Wines from four yeast inocula which showed large sensory differences were subjected to consumer testing by 120 consumers, with differences in overall liking found. Four clusters of consumers were identified, with one group strongly preferring the two-yeast co-inoculated wine with an intermediate sensory profile, while another group favoured the wine made using the three-yeast co-inoculation. This study has demonstrated that the yeast inoculum used to conduct fermentation affects consumer acceptance.
Sandra Regina Ceccatoantonini - One of the best experts on this subject based on the ideXlab platform.
-
interaction of saccharomyces cerevisiae lactobacillus fermentum dekkera bruxellensis and feedstock on fuel ethanol fermentation
Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, 2018Co-Authors: Ana Paula Guarnieri Bassi, Leticia Meneguello, Anna Livia Paraluppi, Beatriz Cristina Pecoraro Sanches, Sandra Regina CeccatoantoniniAbstract:The alcoholic fermentation for fuel ethanol production in Brazil occurs in the presence of several microorganisms present with the starter strain of Saccharomyces cerevisiae in sugarcane musts. It is expected that a multitude of microbial interactions may exist and impact on the fermentation yield. The yeast Dekkera bruxellensis and the bacterium Lactobacillus fermentum are important and frequent contaminants of industrial processes, although reports on the effects of both microorganisms simultaneously in ethanolic fermentation are scarce. The aim of this work was to determine the effects and interactions of both contaminants on the ethanolic fermentation carried out by the industrial yeast S. cerevisiae PE-2 in two different feedstocks (sugarcane juice and molasses) by running multiple batch fermentations with the starter yeast in pure or co-cultures with D. bruxellensis and/or L. fermentum. The fermentations contaminated with D. bruxellensis or L. fermentum or both together resulted in a lower average yield of ethanol, but it was higher in molasses than that of sugarcane juice. The decrease in the CFU number of S. cerevisiae was verified only in co-cultures with both D. bruxellensis and L. fermentum concomitant with higher residual sucrose concentration, lower glycerol and organic acid production in spite of a high reduction in the medium pH in both feedstocks. The growth of D. bruxellensis was stimulated in the presence of L. fermentum resulting in a more pronounced effect on the fermentation parameters than the effects of contamination by each microorganism individually.
-
effects of feedstock and co culture of lactobacillus fermentum and wild saccharomyces cerevisiae strain during fuel ethanol fermentation by the industrial yeast strain pe 2
AMB Express, 2018Co-Authors: Vanda Renata Reis, Ana Paula Guarnieri Bassi, Bianca Carreiro Cerri, Amanda Roberta De Almeida, Isis Gabriela Barbosa Carvalho, Reinaldo Gaspar Bastos, Sandra Regina CeccatoantoniniAbstract:Even though contamination by bacteria and wild yeasts are frequently observed during fuel ethanol fermentation, our knowledge regarding the effects of both contaminants together is very limited, especially considering that the must composition can vary from exclusively sugarcane juice to a mixture of molasses and juice, affecting the microbial development. Here we studied the effects of the feedstock (sugarcane juice and molasses) and the co-culture of Lactobacillus fermentum and a wild Saccharomyces cerevisiae strain (rough colony and pseudohyphae) in single and multiple-batch fermentation trials with an industrial strain of S. cerevisiae (PE-2) as starter yeast. The results indicate that in multiple-cycle batch system, the feedstock had a minor impact on the fermentation than in single-cycle batch system, however the rough yeast contamination was more harmful than the bacterial contamination in multiple-cycle batch fermentation. The inoculation of both contaminants did not potentiate the detrimental effect in any substrate. The residual sugar concentration in the fermented broth had a higher concentration of fructose than glucose for all fermentations, but in the presence of the rough yeast, the discrepancy between fructose and glucose concentrations were markedly higher, especially in molasses. The biggest problem associated with incomplete fermentation seemed to be the lower consumption rate of sugar and the reduced fructose preference of the rough yeast rather than the lower invertase activity. Lower ethanol production, acetate production and higher residual sugar concentration are characteristics strongly associated with the rough yeast strain and they were not potentiated with the inoculation of L. fermentum.