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41.
Aikaterini P. Tzamourani Elisa Di Napoli Spiros Paramithiotis Georgios Economou-Petrovits Stavros Panagiotidis Efstathios Z. Panagou 《International Journal of Food Science & Technology》2021,56(8):3845-3857
The microbiological and physicochemical changes of industrially fermented Halkidiki and Conservolea green table olives were determined. Samples were analysed to monitor the population of lactic acid bacteria (LAB), yeasts and Enterobacteriaceae, together with changes in pH, acidity, salinity, colour, lactic acid, acetic acid and ethanol. LAB and yeast species diversity was evaluated at the beginning (1 day), middle (75 days) and final (135 days) stages of fermentation by RAPD-PCR genomic fingerprinting. Results revealed vigorous lactic acid processes as indicated by the dominance of LAB over yeasts. No Enterobacteriaceae could be detected after 30 days. Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) dominated in the beginning of fermentation in both varieties. In the end, Lactiplantibacillus pentosus (formerly Lactobacillus pentosus) and Pediococcus ethanolidurans prevailed in Halkidiki and Conservolea varieties, respectively. As for yeasts, Kluyveromyces lactis/marxianus and Pichia manshurica prevailed at the onset of fermentation in Halkidiki and Conservolea varieties, whereas in the end Pichia membranifaciens dominated in both varieties. 相似文献
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Tiana D. Warren Krishna Patel Jordan L. Rivera James R. Eshleman Marc Ostermeier 《American Institute of Chemical Engineers》2020,66(3):e16688
Improved prodrug-activating enzymes have the potential to increase the therapeutic efficacy of gene-directed enzyme prodrug therapy (GDEPT). Yeast cytosine deaminase (yCD) is commonly used to convert the prodrug 5-fluorocytosine (5-FC) to the chemotherapeutic 5-fluorouracil for GDEPT. Mutagenesis studies on yCD aimed at improving its application in GDEPT have been limited to subsets of residues or have sought to improve a single property of the enzyme. We performed comprehensive site-saturation mutagenesis (CSM) on yCD designed to create all 2,983 possible unique protein mutants with a single amino acid substitution. We identified active variants through Escherichia coli genetic complementation and screened these mutants, and combinations thereof, for increased ability to sensitize E. coli and HT1080 fibrosarcoma cells to 5-FC. Several mutants identified in this study showed increased sensitization ability for both E. coli and HT1080 cells indicating that CSM is an effective directed evolution tool for identifying unexpectedly beneficial mutations. 相似文献
44.
Sandra Moser Erich Leitner Thomas J. Plocek Koenraad Vanhessche Harald Pichler 《Yeast (Chichester, England)》2020,37(1):163-172
The triterpenoid (+)-ambrein is the major component of ambergris, a coprolite of the sperm whale that can only be rarely found on shores. Upon oxidative degradation of (+)-ambrein, several fragrance molecules are formed, amongst them (−)-ambrox, one of the highest valued compounds in the perfume industry. In order to generate a Saccharomyces cerevisiae whole-cell biocatalyst for the production of (+)-ambrein, intracellular supply of the squalene was enhanced by overexpression of two central enzymes in the mevalonate and sterol biosynthesis pathway, namely the N-terminally truncated 3-hydroxy-3-methylglutaryl-CoA reductase 1 (tHMG) and the squalene synthase (ERG9). In addition, another key enzyme in sterol biosynthesis, squalene epoxidase (ERG1) was inhibited by an experimentally defined amount of the inhibitor terbinafine in order to reduce flux of squalene towards ergosterol biosynthesis while retaining sufficient activity to maintain cell viability and growth. Heterologous expression of a promiscuous variant of Bacillus megaterium tetraprenyl-β-curcumene cyclase (BmeTC-D373C), which has been shown to be able to catalyse the conversion of squalene to 3-deoxyachillol and then further to (+)-ambrein resulted in production of these triterpenoids in S. cerevisiae for the first time. Triterpenoid yields are comparable with the best microbial production chassis described in literature so far, the methylotrophic yeast Pichia pastoris. Consequently, we discuss similarities and differences of these two yeast species when applied for whole-cell (+)-ambrein production. 相似文献
45.
Naoki Yamahata Yosuke Toyotake Satomi Kunieda Mamoru Wakayama 《International Journal of Food Science & Technology》2020,55(4):1698-1704
Various fermented whey-based beverages have been developed to reduce waste. However, approaches to increase the preference of whey-based beverages are required because of the low sensory acceptability of whey. Here, we identified the better starting material (whey type), between raw whey (RW) and demineralised whey (DMW), and determined the optimal initial concentration using multiple sensory evaluations to develop acceptable fermented beverages made from sole whey with pure cultured Kluyveromyces marxianus (i.e. without additional ingredients and processing methods). Acceptance tests showed that fermented beverages made from DMW were superior to RW as the starting material. The amounts of ethanol produced were 5.0%, 7.6% and 9.5% v/v from the different initial DMW concentrations of 10%, 15% and 20% w/v, respectively. We observed a significant positive correlation (rs = 0.32, P < 0.05) between the assessment attributes, strength of taste as alcohol beverage and overall acceptability, indicating that higher concentrations of DMW yielded a more desirable product. 相似文献
46.
Improvement in lactone production from biotransformation of ricinoleic acid based on the porous starch delivery system 下载免费PDF全文
47.
《International Journal of Hydrogen Energy》2022,47(3):1516-1528
Enhanced hydrogen evolution was pursued in this work. Rhodobacter sp. (Rb) and Rhodopseudomonas palustris (Rp), single or mixed were used to extract hydrogen molecules from Chlorella fusca biomass. To elevate their fermentable contents, Chlorella was grown at nitrogen and/or phosphorus deprivation. Besides, cellulase and/or macerozyme, Triton X100 or sonicated yeast were applied for further biohydrogen fermentation. Utilizing hydrolysates of mineral deprived Chlorella cultures, Rb exhibited relatively higher cumulative hydrogen (4200 ml L?1) than Rp (2500 ml L?1) while mixed cultures attained significantly higher levels (4700 ml L?1). Triton or enzymes significantly enhanced hydrogen evolution, with more effectiveness of macerozyme than cellulase. A novel use of sonicated yeast, as enzymes pool, induced the highest significant collective H2 (up to 47 times that of microalgal supernatant). Sonicated yeast induced a remarkable hydrolysis of algae, as inferred from increased reducing sugars. However, hydrogen evolution efficiency exhibited poor proportionality with reducing sugars, indicating fermentation of other metabolites. 相似文献
48.
A. Chandralekha Anupama Rani Hrishikesh A. Tavanandi N. Amrutha Umesh Hebbar 《Drying Technology》2017,35(8):1029-1042
ABSTRACTYeast was encapsulated using different carrier materials and their combinations to explore the possible synergistic effect of carrier material during encapsulation using spray drying. Freeze-drying was performed for comparison. The dried cell powders were analyzed for the quality aspects (morphology, flowability, and storage stability). The best results were observed, with a combination of whey protein and corn starch (cell survival: 82.37% and yield: 56%, w/w) with a shelf life of 6 months (with only 10% reduction in cell survival). The survival was found to be 40% without any carrier material, which decreased to less than 25% within 4 weeks. 相似文献
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