Fermentation Ability Research Articles

Mutations in degP and spoT Genes Mediate Response to Fermentation Stress in Thermally Adapted Strains of Acetic Acid Bacterium Komagataeibacter medellinensis NBRC 3288.

An acetic acid bacterium, Komagataeibacter medellinensis NBRC 3288, was adapted to higher growth temperatures through an experimental evolution approach in acetic acid fermentation conditions, in which the cells grew under high concentrations of ethanol and acetic acid. The thermally adapted strains were shown to exhibit significantly increased growth and fermentation ability, compared to the wild strain, at higher temperatures. Although the wild cells were largely elongated and exhibited a rough cell surface, the adapted strains repressed the elongation and exhibited a smaller cell size and a smoother cell surface than the wild strain. Among the adapted strains, the ITO-1 strain isolated during the initial rounds of adaptation was shown to have three indel mutations in the genes gyrB, degP, and spoT. Among these, two dispensable genes, degP and spoT, were further examined in this study. Rough cell surface morphology related to degP mutation suggested that membrane vesicle-like structures were increased on the cell surface of the wild-type strain but repressed in the ITO-1 strain under high-temperature acetic acid fermentation conditions. The ΔdegP strain could not grow at higher temperatures and accumulated a large amount of membrane vesicles in the culture supernatant when grown even at 30°C, suggesting that the degP mutation is involved in cell surface stability. As the spoT gene of ITO-1 lost a 3′-end of 424 bp, which includes one (Act-4) of the possible two regulatory domains (TGS and Act-4), two spoT mutant strains were created: one (ΔTGSAct) with a drug cassette in between the 5′-half catalytic domain and 3′-half regulatory domains of the gene, and the other (ΔAct-4) in between TGS and Act-4 domains of the regulatory domain. These spoT mutants exhibited different growth responses; ΔTGSAct grew better in both the fermentation and non-fermentation conditions, whereas ΔAct-4 did only under fermentation conditions, such as ITO-1 at higher temperatures. We suggest that cell elongation and/or cell size are largely related to these spoT mutations, which may be involved in fermentation stress and thermotolerance.

Development of a Wet-Granulated Sourdough Multiple Starter for Direct Use.

The search for sourdough starters for the direct production of baked goods with all the advantages of biological sourdough fermentation is still a crucial issue. In this study, 43 Lactic Acid Bacteria strains isolated from mature sourdoughs were evaluated for features of technological interest and tested for fermentation ability. Three microbial combinations were selected and used to produce bread. Based on GC-MS and sensory analysis, bread made by using the three combinations of strains was characterized by a more complex aroma profile with the prevalence of VOCs typical of sourdough bread. To set up the best way to keep microbial viability upon drying, the three combinations were subject to freeze-drying and wet granulation, with the latter being used for the first time for food starters’ stabilization. Wet granulation ensured optimal strains’ viability. Surprisingly, the height attained by mature sourdoughs when inoculated with wet granulated starters was constantly higher than the height reached by sourdoughs made with the same starters as fresh cells. The microbial combination E75-B72 exhibited the best performances and may represent a starter able to ensure sourdough bread production in 16 h of fermentation at 28 °C.

Evolutionary Adaptation by Repetitive Long-Term Cultivation with Gradual Increase in Temperature for Acquiring Multi-Stress Tolerance and High Ethanol Productivity in Kluyveromyces marxianus DMKU 3-1042.

During ethanol fermentation, yeast cells are exposed to various stresses that have negative effects on cell growth, cell survival, and fermentation ability. This study, therefore, aims to develop Kluyveromyces marxianus-adapted strains that are multi-stress tolerant and to increase ethanol production at high temperatures through a novel evolutionary adaptation procedure. K. marxianus DMKU 3-1042 was subjected to repetitive long-term cultivation with gradual increases in temperature (RLCGT), which exposed cells to various stresses, including high temperatures. In each cultivation step, 1% of the previous culture was inoculated into a medium containing 1% yeast extract, 2% peptone, and 2% glucose, and cultivation was performed under a shaking condition. Four adapted strains showed increased tolerance to ethanol, furfural, hydroxymethylfurfural, and vanillin, and they also showed higher production of ethanol in a medium containing 16% glucose at high temperatures. One showed stronger ethanol tolerance. Others had similar phenotypes, including acetic acid tolerance, though genome analysis revealed that they had different mutations. Based on genome and transcriptome analyses, we discuss possible mechanisms of stress tolerance in adapted strains. All adapted strains gained a useful capacity for ethanol fermentation at high temperatures and improved tolerance to multi-stress. This suggests that RLCGT is a simple and efficient procedure for the development of robust strains.

Public Opinion Guidance and Communication Mechanism Innovation of Public Health Events Based on the Multitask Learning Network in the Internet Era

In order to improve the public opinion guidance ability for public health events in the Internet era, and improve the the problems of the traditional public opinion guidance mechanism, we analyze the public opinion guidance and communication mechanism based on the Internet era, and analyze the guidance software and software system, and related technical requirements? subsequently, the efficiency analysis of the public opinion guidance and communication mechanism of the multitask learning network was conducted; the results show that the public opinion guidance and communication mechanism of public health events based on the multitask learning network can effectively improve the diagnostic and early warning ability and diagnostic accuracy of the public opinion fermentation in public health emergencies, reduce the difficulty of guiding the public opinion fermentation of public health emergencies, and effectively improve the success rate of guidance for such events. In the Internet era, the public opinion guidance and communication mechanism based on the multitask learning network has improved the public opinion guidance ability for public health events, and it provides a research direction for the development of the network public opinion guidance system for unconventional public health emergencies in the future.

Sex differences in rumen fermentation and microbiota of Tibetan goat

BackgroundThe gut microbiota play an important role in maintaining host metabolism, the immune system and health, while sex, genotype, diet and health have specific effects on the composition of the gut microbiota. Therefore, to explore the sex differences in the structure and function of rumen microbiota in Tibetan goats, herein we analyzed sex differences in rumen fermentation parameters, rumen microbiota and the expression of genes related to VFA transport in Tibetan goats.ResultsThe results showed that the contents of acetic acid and propionic acid in the rumen of TGM (Tibetan goat male) were significantly higher than those in TGFm (Tibetan goat female) (P < 0.05), and total VFAs was significantly higher in TGM than TGFm (P < 0.05). Expression of the VFA transport-related genes DRA, AE2, MCT-1, NHE1, and NHE2 in the rumen epithelium of TGFm was significantly higher than that in TGM. Analysis of the composition and structure of the rumen microbiota revealed significant sex differences. At the phylum level, Firmicutes and Bacteroidetes were the dominant phyla in Tibetan goats. In addition, Fibrobacteres and Spirochaetes had significantly greater relative abundances in TGFm than in TGM (P < 0.05). At the genus level, the relative abundance of Fibrobacter, Ruminococcus_1 and Pyramidobacter was significantly higher in TGFm than in TGM (P < 0.05). The functional prediction results showed that replication, recombination and repair, RNA processing and modification were mainly enriched in TGFm (P < 0.05).ConclusionsCorrelation analysis revealed significant associations of some rumen microbiota with the fermentation product VFAs and VFA transport-related genes. We concluded that yearling TGM and TGFm have distinct fermentation and metabolism abilities when adapting to the plateau environment, which provides a certain sex reference basis for Tibetan goat adaptation to the plateau environment.

다양한 유산균으로 제조한 발효마늘의 품질 특성

This study aimed to investigate quality characteristics and antioxidant activity of garlic fermented by lactic acid bacteria (LAB). Four LAB strains (Lactobacillus plantarum KCTC3108, Lactobacillus plantarum B8, Lactobacillus plantarum BR4 and Leuconostoc mesenteroides SY3) were selected for analysis based on their fermentation ability (pH and total acidity) from eight LAB strains isolated from fermented foods. Quality characteristics and antioxidant activity were measured during four days of fermentation. S-allyl-L-cysteine, total thiosulfinate content, total flavonoid content and ferric reducing antioxidant power of fermented garlic extract increased as fermentation progressed. After fermentation, the S-allyl-L-cysteine contents of garlic samples fermented with L. plantarum KCTC3108, L. plantarum B8, L. plantarum BR4 and Leuconostoc mesenteroides SY3 increased 2.34, 2.30, 1.96 and 2.62 times, respectively, and the total thiosulfinate contents increased 5.55, 6.06, 14.41, and 7.56 times, respectively, compared to those at the beginning of fermentation. Ferric reducing antioxidant power and total flavonoid content were 23.64 mg/mL and 144.65 μg/mL, respectively in garlic samples fermented with L. plantarum BR4 which were the highest values among the groups. Based on these results, L. plantarum BR4 was selected for garlic fermentation to develop a functional food.

A novel strategy of gene screen based on multi-omics in Streptomyces roseosporus.

Daptomycin is a new lipopeptide antibiotic for treatment of severe infection caused by multi-drug-resistant bacteria, but its production cost remains high currently. Thus, it is very important to improve the fermentation ability of the daptomycin producer Streptomyces roseosporus. Here, we found that the deletion of proteasome in S. roseosporus would result in the loss of ability to produce daptomycin. Therefore, transcriptome and 4D label-free proteome analyses of the proteasome mutant (Δprc) and wild type were carried out, showing 457 differential genes. Further, five genes were screened by integrated crotonylation omics analysis. Among them, two genes (orf04750/orf05959) could significantly promote the daptomycin synthesis by overexpression, and the fermentation yield in shake flask increased by 54% and 76.7%, respectively. By enhancing the crotonylation modification via lysine site mutation (K-Q), the daptomycin production in shake flask was finally increased by 98.8% and 206.3%, respectively. This result proved that the crotonylation modification of appropriate proteins could effectively modulate daptomycin biosynthesis. In summary, we established a novel strategy of gene screen for antibiotic biosynthesis process, which is more convenient than the previous screening method based on pathway-specific regulators. KEY POINTS: • Δprc strain has lost the ability of daptomycin production • Five genes were screened by multi-omics analysis • Two genes (orf04750/orf05959) could promote the daptomycin synthesis by overexpression.

Enhancing Ethanol Tolerance via the Mutational Breeding of Pichia terricola H5 to Improve the Flavor Profiles of Wine

Although using non-Saccharomyces yeasts during alcoholic fermentation can improve the wine aroma, most of them are not ethanol tolerant; therefore, in 2017, this study screened 85 non-Saccharomyces yeasts isolated and identified from 24 vineyards in seven Chinese wine-producing regions, obtaining Pichia terricola strain H5, which displayed 8% ethanol tolerance. Strain H5 was subjected to ultraviolet (UV) irradiation and diethyl sulfate (DES) mutagenesis treatment to obtain mutant strains with different fermentation characteristics from the parental H5. Compared with strain H5, the UV-irradiated strains, UV5 and UV8, showed significantly higher ethanol tolerance and fermentation capacity. Modified aroma profiles were also evident in the fermentation samples exposed to the mutants. Increased ethyl caprate, ethyl caprylate, and ethyl dodecanoate content were apparent in the UV5 samples, providing the wine with a distinctly floral, fruity, and spicy profile. Fermentation with strain UV8 produced a high ethyl acetate concentration, causing the wine to present a highly unpleasant odor. To a certain extent, UV irradiation improved the ethanol tolerance and fermentation ability of strain H5, changing the wine aroma profile. This study provides a theoretical basis for the industrial application of non-Saccharomyces yeasts that can improve wine flavor.

Valorization of Lactic Acid Fermentation of Pomegranate Juice by an Acid Tolerant and Potentially Probiotic LAB Isolated from Kefir Grains

The present study describes the application of an acid tolerant and potentially probiotic L. paracasei SP3 strain, recently isolated from kefir grains, in the production of a novel functional beverage based on the fermentation of pomegranate juice. The fermentation ability of the novel strain was assessed during pomegranate juice fermentations at 30 °C for 24 h and storage at 4 °C for 4 weeks. Various parameters were assessed such as residual sugar, organic acid and alcohol levels, total phenolics content, antioxidant activity, astringency, cell viability, and consumer acceptance. Residual sugar was decreased by approximately 25%, while respectable amounts of lactic acid were determined (4.8 g/L) on the 28th day of storage, proving that the novel strain was effective at lactic acid fermentation. The concentration of ethanol was maintained at low levels (0.3–0.4 % v/v) and low levels of acetic acid were detected (0.6 g/L). The viability of L. paracasei SP3 cells retained high levels (&gt;7 log cfu/mL), even by the 4th week. The total phenolic content (123.7–201.1 mg GAE/100 mL) and antioxidant activity (124.5–148.5 mgTE/100 mL) of fermented pomegranate juice were recorded at higher levels for all of the studied time periods compared to the non-fermented juice. The employment of the novel strain led to a significant reduction in the levels of hydrolysable tannins (42%) in the juice, reducing its astringency. The latter was further proven through sensorial tests, which reflected the amelioration of the sensorial features of the final product. It should be underlined that fruit juices as well as pomegranate juice comprised a very harsh food matrix for microorganisms to survive and ferment. Likewise, the L. paracasei SP3 strain showed a significant potential, because it was applied as a free culture, without the application of microencapsulation methods that are usually employed in these fermentations, leading to a product with possible functional properties and a high nutritive value.

SINGLE CELL PROTEIN PRODUCTION FROM PLANTAIN AND BANANA PEELS

The fermentative ability of Saccharomyces cerevisiae to grow and produce biomass protein from pretreated plantain and banana peels as substrate was studied. Plantain peels had a moisture content of 6.95±0.05%, ash (22.33±0.01%), protein (7.10±0.10%), fat (6.18±0.04%), crude fibre (13.99±0.20%) and carbohydrate (43.45±0.10%). The banana peels had corresponding values of 6.70±0.00%, 8.45±0.02%, 4.90±0.05%, 1.65±0.01%, 11.70±0.10% and 66.60±0.70% in that order. During fermentation the pH decreased from 4.1 to 2.3 and 2.5 in the plantain and banana peel media, while the titratable acidity increased from 0.7 to 4.1 and 3.5 in the plantain and banana peel media respectively. There was a higher yield of biomass with the plantain peels which gave a maximum cell density of 2.973 (OD) on the 7th day compared to the banana peels which reached the peak on the 7th day with a maximum cell density of 2.492.The yeast population increased during the fermentation period from 6.69Log10cfu/ml to 7.58Log10cfu/ml in the plantain and 6.69Log10cfu/ml to 7.53Log10cfu/ml in banana peel media respectively. The dry mass of S. cerevisiae harvested from plantain and banana peel medium per 100 ml were 2.71±0.01g and 4.28±0.06g with protein contents of 13.95±0.71% and 11.70±0.50% with plantain peel media having the higher yield

Molecular mechanism of ethanol fermentation inhibition via protein tyrosine nitration of pyruvate decarboxylase by reactive nitrogen species in yeast

Protein tyrosine nitration (PTN), in which tyrosine (Tyr) residues on proteins are converted into 3-nitrotyrosine (NT), is one of the post-translational modifications mediated by reactive nitrogen species (RNS). Many recent studies have reported that PTN contributed to signaling systems by altering the structures and/or functions of proteins. This study aimed to investigate connections between PTN and the inhibitory effect of nitrite-derived RNS on fermentation ability using the yeast Saccharomyces cerevisiae. The results indicated that RNS inhibited the ethanol production of yeast cells with increased intracellular pyruvate content. We also found that RNS decreased the activities of pyruvate decarboxylase (PDC) as a critical enzyme involved in ethanol production. Our proteomic analysis revealed that the main PDC isozyme Pdc1 underwent the PTN modification at Tyr38, Tyr157, and Tyr344. The biochemical analysis using the recombinant purified Pdc1 enzyme indicated that PTN at Tyr157 or Tyr344 significantly reduced the Pdc1 activity. Interestingly, the substitution of Tyr157 or Tyr344 to phenylalanine, which is no longer converted into NT, recovered the ethanol production under the RNS treatment conditions. These findings suggest that nitrite impairs the fermentation ability of yeast by inhibiting the Pdc1 activity via its PTN modification at Tyr157 and Tyr344 of Pdc1.

Adaptive response and tolerance to weak acids in Saccharomyces cerevisiae boulardii: a metabolomics approach

SummaryWeak acids inhibit the growth of probiotics, such as Saccharomyces boulardii. We explored the tolerance of S. boulardii to different weak acids. S. boulardii had better fermentation ability under lactic acid conditions compared with acetic and butyric acid conditions; however, the budding of S. boulardii was significantly stronger than that of Saccharomyces cerevisiae under acetic acid conditions. Although the surface structure of S. boulardii was destroyed, it produced more daughter cells. S. boulardii metabolites were also significantly different from S. cerevisiae under acidic stress. The growth of S. boulardii under weak acid conditions differed significantly from that of S. cerevisiae. S. boulardii‐mediated fingerprints under weak acid conditions were identified as latent biomarkers, related to fructose and mannose metabolism, tricarboxylic acid cycle, and the glycolysis pathway. Identified biomarkers will aid in the genetic engineering of S. boulardii and other Saccharomyces strains for improved acid resistance and biomass yield.

Lactic Acid Bacteria from African Fermented Cereal-Based Products: Potential Biological Control Agents for Mycotoxins in Kenya.

Cereals play an important role in global food security. Data from the UN Food and Agriculture Organization projects increased consumption of cereals from 2.6 billion tonnes in 2017 to approximately 2.9 billion tonnes by 2027. However, cereals are prone to contamination by toxigenic fungi, which lead to mycotoxicosis. The current methods for mycotoxin control involve the use of chemical preservatives. However, there are concerns about the use of chemicals in food preservation due to their effects on the health, nutritional quality, and organoleptic properties of food. Therefore, alternative methods are needed that are affordable and simple to use. The fermentation technique is based on the use of microorganisms mainly to impart desirable sensory properties and shelf-life extension. The lactic acid bacteria (LAB) are generally regarded as safe (GRAS) due to their long history of application in food fermentation systems and ability to produce antimicrobial compounds (hydroxyl fatty acids, organic acids, phenyllactic acid, hydrogen peroxide, bacteriocins, and carbon dioxide) with a broad range of antifungal activity. Hence, LAB can inhibit the growth of mycotoxin-producing fungi, thereby preventing the production of mycotoxins. Fermentation is also an efficient technique for improving nutrient bioavailability and other functional properties of cereal-based products. This review seeks to provide evidence of the potential of LAB from African fermented cereal-based products as potential biological agents against mycotoxin-producing fungi.

Adaptive Laboratory Evolution for Multistress Tolerance, including Fermentability at High Glucose Concentrations in Thermotolerant Candida tropicalis

Candida tropicalis, a xylose-fermenting yeast, has the potential for converting cellulosic biomass to ethanol. Thermotolerant C. tropicalis X-17, which was isolated in Laos, was subjected to repetitive long-term cultivation with a gradual increase in temperature (RLCGT) in the presence of a high concentration of glucose, which exposed cells to various stresses in addition to the high concentration of glucose and high temperatures. The resultant adapted strain demonstrated increased tolerance to ethanol, furfural and hydroxymethylfurfural at high temperatures and displayed improvement in fermentation ability at high glucose concentrations and xylose-fermenting ability. Transcriptome analysis revealed the up-regulation of a gene for a glucose transporter of the major facilitator superfamily and genes for stress response and cell wall proteins. Additionally, hydropathy analysis revealed that three genes for putative membrane proteins with multiple membrane-spanning segments were also up-regulated. From these findings, it can be inferred that the up-regulation of genes, including the gene for a glucose transporter, is responsible for the phenotype of the adaptive strain. This study revealed part of the mechanisms of fermentability at high glucose concentrations in C. tropicalis and the results of this study suggest that RLCGT is an effective procedure for improving multistress tolerance.

Characterization of Lactobacillus zeae as probiotic and starter culture for tamarillo fermented product

Probiotic was known as the microorganism that can improve human health. It can be in the form of supplements, probiotic food, or fermented food. Probiotic delivery as fermented food has several challenges. Bacteria must have characteristics as probiotics and must be able as a starter culture for fermentation. The characteristics of probiotics were safety, functionality, and high viability during manufacturing, storage, and transit in the gastrointestinal tract. Some fruit-based fermentations provide a protective environment for probiotics that can improve viability. This study aimed to isolate Lactobacillus, potentially a probiotic and a starter culture for tamarillo juice fermentation. The isolate was characterized for antibiotic susceptibility, haemolytic activity, lysozyme, acid and bile salt resistance, antimicrobial activity, bile salt hydrolase activity, and tamarillo's fermenting ability. Lactobacillus plantarum and Lactobacillus acidophilus were used as comparison bacteria in this study. The results indicated that Lactobacillus zeae could be isolated from tamarillo fruit. It was potential as a probiotic, which was safe and had functional properties. Then, it has high resistance to lysozyme, acid, and bile salt, with the percentage of survival successively 92.62, 89.93, and 96.75%. L. zeae can grow in tamarillo juice until the 30th hours.

Survival and fermentation ability of indigenous yeast isolates in Seabuckthorn (Hippophae rhamnoides L.) juice

Survival and fermentation ability of indigenous yeast isolates in Seabuckthorn (Hippophae rhamnoides L.) juice

Technological Characteristics of Wild Non-Saccharomyces Sourced from Banana Fruit and Honey

This study is aimed at evaluating the technological characteristics of wild non-Saccharomyces sourced from banana fruit and wild honey. The isolation of yeasts was done according to standard microbiological procedures. Technological traits screened for are as follows: fermentation ability, alcohol production, flocculation ability, organic acid production, and hydrogen sulphide production. Five yeast isolates were identified as B10 (Candida tropicalis), B7 (Candida tropicalis), H4 (Candida tropicalis), H7 (Clavisporalusitaniae), and CY (Candida tropicalis), which are sugar fermenters. The percentage of alcohol produced from each sugar fermented by the yeast isolates are as follows: sucrose - B7(11.50%) &gt; H7(8.62%) &gt; CY (7.80%) &gt; H4(4.88%) &gt; B10 (4.11%); Glucose - B7(9.82%) &gt; CY (6.28%) &gt; B10(4.56%) &gt; H7(4.03%) &gt; H4(2.19%) and Fructose - H7(13.11%) &gt; CY (9.40%) &gt; B10(7.03%) &gt; H4(4.41%) &gt; B7(3.70%). Yeast isolate CY demonstrated high flocculation of 28.55 and 44.75 (%) at 5 and 15 (minutes). The organic acid produced by the yeast isolates B10, B7, CY, H4 and H7 are as follows 1.90±0.41, 3.10±0.41, 1.25±0.07, 3.90±0.41 and 2.40±0.41 (AU) respectively and Yeast isolates B7, CY, H4, and H7 produced low hydrogen sulphite concentration. Wild non-Saccharomyces could be the hope of the wine microbiologist to ease the challenges in the wine industry, as they competed flavourably with the commercial wine yeast.

Adaptation of Saccharomyces cerevisiae in a concentrated spent sulphite liquor waste stream for increased inhibitor resistance.

The fermentation of spent sulphite liquor (SSL) from the pulping of hardwoods is limited by the combination of xylose, the primary fermentable sugar and high concentrations of microbial inhibitors that decrease the yeast fermentation ability. The inhibitor resistance phenotypes of xylose-capable Saccharomyces cerevisiae strains were therefore enhanced by combining rational engineering for multi-inhibitor tolerance, with adaptation in concentrated hardwood SSL as selective pressure. The adapted strains were assessed in fermentations with 60-80% v/v concentrated SSL under industrially relevant fermentation conditions. During adaptation, strains produced ethanol concentrations between 11.0 and 15.4 g/L in the range of that reported in literature. The adapted TFA40 and TP50 strains displayed enhanced inhibitor resistance phenotypes and were able to ferment xylose-rich SSL at pH below 5, exhibiting improved ethanol yields relative to the reference strain. Using yeast extract and peptone as nitrogen source in concentrated SSL fermentations further improved ethanol yields. However, strains exhibited a trade-off between resistance and ethanol productivity, indicating a carbon/energy cost for the expression of this inhibitor tolerance phenotype. KEY POINTS : • Achieved fermentation of xylose-rich hardwood spent sulphite liquor at pH below 5.0 • Adaptation of xylose-capable S. cerevisiae in concentrated spent sulphite liquor • Adapted strains exhibited enhanced inhibitor resistance phenotypes.

Isolation and Identification of Lactic Acid Bacteria from Naturally Fermented Pickles from Ningxia and Its Application in Goji Berry Juice Fermentation

Using 3 home-made fermented pickles from Yinchuan city of Ningxia as material, lactic acid bacteria with high acid production were selected,and identified through morphological observation, physiological and biochemical tests and molecular biology techniques, and their acid resistance, bile salt resistance,salt tolerance and fermentation ability were determined.The lactic acid bacteria with excellent performance were screened and finally applied to fermented Goji berry juice. The results showed that 5 strains of lactic acid bacteria with high acid production were obtained,one strains was identified as Lactobacillus plantarum NXU_ 19010, one strain was identified as Lactobacillus rhamnosus NXU_ 19023, one strain was identified as Lactobacillus pentosus NXU_ 19006, one strain was identified as Lactobacillus helveticus NXU_ 19022, one strain was identified as Lactobacillus paracasei NXU_ 19004.Among them, Lactobacillus helveticus NXU_ 19022 had good acid resistance, bile salt resistance and growth performance, at about 6 h, it began to be logarithmic growth phase, thesurvival rate was about 92% at pH2 and the survival rate was about 18% when the bile salt content was 0.9%. the polysaccharide content of fermented Goji berry juice by NXU_ 19022 increased by 29%, and the polyphenol content fermented Goji berry juice decreased to 91%, the sensory score was the best and could significantly improve the free radical scavenging rate and flavor quality of fermented Goji berry juice. Analyzed the volatile components of unfermented and fermentad Goji berry juice by the non-targeted metabonomics analysis technology, a total of 20 metabolites were identified as differential metabolites. The content of lipids, aroma and sweet substances increased. The results showed that the strain had good fermentation characteristics and could be further developed and utilized as a production strain of fermentation products.

Evaluation of Anaerobic Glucose Utilization by Escherichia coli Strains with Impaired Fermentation Ability during Respiration with External and Internal Electron Acceptors

Evaluation of Anaerobic Glucose Utilization by Escherichia coli Strains with Impaired Fermentation Ability during Respiration with External and Internal Electron Acceptors