Acid Production Ability Research Articles

Determination of Technological Properties and CRISPR Profiles of Streptococcus thermophilus Isolates Obtained from Local Yogurt Samples.

The aim of this study was to obtain data on Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) profiles of Streptococcus thermophilus (S. thermophilus) isolates resulting from acquired immune memory in addition to their technological starter properties for the selection of potential starter cultures from local yogurt samples. A total of 24 S. thermophilus isolates were collected from six local yogurt samples including Afyon/Dinar, Uşak, Konya/Karapınar, and Tokat provinces of Türkiye. Strain-specific CRISPR I-II-III and IV primers were used to determine the CRISPR profiles of the isolates. The isolates commonly had CRISPR II and IV profiles, while only one isolate had a CRISPR III profile. Polymerase chain reaction (PCR)-based and culture-based analyses were also carried out to obtain data on the technological properties of the isolates. The PCR analyses were performed for the prtS gene for protease activity, the ureC gene for urease enzyme, the gdh gene for glutamate dehydrogenase, the cox gene for competence frequency, the csp gene involved in heat-shock stress resistance of the isolates with specific primers. Culture-based analyses including antimicrobial activity and acid-production ability of the isolates were completed, and proteolytic and lipolytic properties were also screened. Native spacer sequences resulting from acquired immune memory were obtained for CRISPR IV profiles of yogurt samples from the Konya-Karapınar and Tokat provinces and CRISPR III profiles of yogurt samples from the Uşak province. In conclusion, our study results suggest that it is possible to select the isolates with the desired level of technological characteristics, prioritizing the ones with the most diverse CRISPR profiles and with native spacers for potential industrial application as starter cultures. We believe that this study provides data for further biological studies on the impact of centuries of human domestication on evolutionary adaptations and how these microorganisms manage survival and symbiosis.

Corrosion of carbon steel by Pseudomonas stutzeri CQ-Z5 in simulated oilfield water

Carbon steel, an important infrastructure material in the petroleum industry, experiences serious damage due to Microbially Influenced Corrosion (MIC) with untold economic impact. Pseudomonas stutzeri CQ-Z5 with solid biofilm formation and organic acid-producing ability was isolated from Changqing oilfield produced water. The corrosion behavior and mechanism of 20# carbon steel by P. stutzeri CQ-Z5 were explored in a simulated oilfield product water circulating device. Bacteria inoculation can hasten steel corrosion, the maximum corrosion rate reached 1.84 mm y−1. Pitting corrosion on rust layer was observed using SEM, and CLSM monitored the change in biofilm thickness. XRD displayed that oxides were the primary corrosion products, including Fe2O3, Fe3O4, and FeOOH. Analysis of contributions of corrosion types indicated that biofilm corrosion contributes 72 % to total corrosion, far higher than those of ion erosion and organic acid decay. Many genes involved in iron metabolism, biofilm synthesis, and organic acid production were annotated in the genome of P. stutzeri CQ-Z5. Accordingly, a hypothetical corrosion mechanism model of P. stutzeri CQ-Z5 for carbon steel involvement of initial ion erosion, then biofilm corrosion and organic acid decay was proposed. The work helped prevent carbon steel corrosion and improve corrosion mitigation strategies.

In Vitro Screening of Trehalose Synbiotics and Their Effects on Early-Lactating Females and Offspring Mice.

Activities such as childbirth and breastfeeding can cause severe oxidative stress and inflammatory damage to the mother during early lactation, and can affect animal milk production, and the growth and development of offspring. Trehalose alleviates damage to the body by endowing it with stress resistance. In this study, we used trehalose combined with Lactobacillus plantarum, Bifidobacterium longum, Bacillus subtilis, and Saccharomyces cerevisiae to explore whether dietary intervention can alleviate oxidative stress and inflammatory damage in early lactation and to evaluate the growth ability, acid production ability, antioxidant ability, non-specific adhesion ability, antibacterial ability, and other parameters to determine the optimal combinations and proportions. The results showed that the synbiotics composed of 2.5% trehalose and 1 × 107 cfu/g of Bifidobacterium longum could regulate the gut microbiota, and promote mammary gland development in dams by reducing progesterone (PROG) content in the blood, increasing prolactin (PRL) and insulin-like growth factor-1 (IGF-1) content, enhancing their antioxidant and immune abilities, and effectively increasing the weight and lactation of early lactating dams. In addition, it can also affect the growth of offspring and the development of the intestinal barrier. These results indicate that trehalose synbiotics have great potential in alleviating oxidative stress and inflammatory damage in early lactation.

The role of Ni- and Cd-resistant rhizobacteria in promoting the growth of rice seedlings and alleviating the combined phytotoxicity of Ni and Cd

The problem of potentially toxic metal pollution is increasingly acute with the development of human society. In this study, we investigated the remediation of nickel (Ni) and cadmium (Cd) co-contamination through inoculating rice with three new-isolated Ni- and Cd-resistant plant growth-promoting rhizobacteria (PGPR) Y3, Y4, and Y5. These three strains possessed growth-promoting properties, including 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, the ability of indoleacetic acid (IAA) production, phosphate solubilization, siderophores production, and exopolysaccharide (EPS) development. According to 16S rDNA sequence homology, strains Y3, Y4, and Y5 were identified as Pseudomonas sp., Chryseobacterium sp., and Enterobacter sp., respectively. Based on the results of rice germination experiments conducted under combined toxicity, we set the contamination concentrations for Ni2+ at 20 μg mL−1 and Cd2+ at 40 μg mL−1. Then we conducted potting experiments at these concentration levels to study the effects of strains Y3, Y4, and Y5 on rice growth under synergistic Ni and Cd stress. The results indicated that the inoculated strains Y3, Y4, and Y5 were effective in promoting the growth of rice seedlings under the combined stress of Ni and Cd, and conferring tolerance to Ni and Cd by increasing the antioxidant enzyme activities of the seedlings. Among them, strain Y3 exhibited stronger ACC deaminase activity, IAA production capacity, and EPS production capacity, showing the most pronounced growth-promoting effect on rice. It was demonstrated that after inoculation with strain Y3, the germination rate of rice seeds increased by 43 %, the fresh weight of stems improved by 35 %, and the chlorophyll content enhanced by 70 % and other growth-promoting phenomena. Additionally, under Ni and Cd stress, strain Y5 performed better than strain Y4 in terms of IAA production capacity and its influence on rice root growth, suggesting that IAA production might play a specifically essential role in root growth under Ni and Cd stress.

Characterization of a new style tofu coagulated by fermentation of Lactobacillus plantarum SJ-L-1.

A new style of tofu coagulated through the fermentation of Lactobacillus plantarum SJ-L-1 was produced. L. plantarum SJ-L-1 with a high growth rate and excellent acid production ability was isolated and identified from naturally fermented soy yellow whey. The gene annotation indicated the potential outstanding isoflavone conversion capacity of L. plantarum SJ-L-1. Furthermore, fermentation tofu was prepared using L. plantarum SJ-L-1 and Lactobacillus rhamnosus 1-16 as the starter microbiota. Compared to traditional MgCl2 tofu and fermented soy whey tofu, SJ-L-1 tofu exhibited a slight increase in hardness and better structure uniformity. SJ-L-1 tofu also possessed the highest levels of total isoflavone content (76.33µg/g) and volatile compounds (561.54µg/kg) among the four styles of tofu. This research indicated that this new type of tofu coagulated through a combination of heat and fermentation of L. plantarum SJ-L-1 represents a promising candidate for future functional foods.

Effect of Using Mouthwash Containing Cibotium barometz J. Smith on Cariogenic Bacteria and Acid-producing Ability of Saliva: A Randomised Blinded Clinical Trial.

To examine the anti-caries effect of mouthwashes containing Cibotium barometz J. Smith (CB), a natural substance, and compare it with chlorhexidine and saline solution. A randomised, blinded clinical trial was conducted on 76 study participants. The differences between the 3 gargle groups (saline gargle: SAL; chlorhexidine gargle: CHX; CB gargle group: CB) and the differences over time (baseline, after 1 week, after 2 weeks) were compared. To this end, ANOVA was performed on caries-related clinical indicators (e.g. O'Leary plaque index, caries activity, and satisfaction). The O'Leary index, caries activity, and saliva tests, gradually improved in group CB at one and two weeks. In the case of bacterial tests, unlike SAL and CHX, only in group CB did the decrease occur one and two weeks later. The caries-related indicators decreased significantly over time in group CB compared to SAL and CHX groups, and there was also a statistically significant difference in interaction between groups and time (p<0.05). The mouthwash containing CB extract showed statistically significant improvement in biofilm adhesion as well as the saliva and bacterial tests compared to SAL and CHX. However, since there were differences in the initial oral conditions of the three groups, additional long-term research is needed through crossover clinical trials to supplement these.

Chemical composition, cytotoxicity, antimicrobial, antibiofilm, and anti-quorum sensing potential of Mentha Piperita essential oil against the oral pathogen Streptococcus mutans

ABSTRACT Dental caries is a highly prevalent oral disease affecting billions of individuals globally. The disease occurs chemically as a result of breakdown of the tooth surface attributed to metabolic activity in colonizing biofilm. Biofilms, composed of exopolysaccharides and proteins, protect bacteria like Streptococcus mutans, which is notable for its role in tooth decay due to its acid-producing abilities. While various antimicrobial agents may prevent biofilm formation, these drugs often produce side effects including enamel erosion and taste disturbances. This study aimed to examine utilization of the Mentha piperita essential oil as a potential antibiofilm activity agent against S. mutans. M. piperita oil significantly (1) reduced bacterial biofilm, (2) exhibited a synergistic effect when combined with chlorhexidine, and (3) did not induce cell toxicity. Chemical analysis identified the essential oil with 99.99% certainty, revealing menthol and menthone as the primary components, constituting approximately 42% and 26%, respectively. Further, M. piperita oil eradicated preformed biofilms and inhibited biofilm formation at sub-inhibitory concentrations. M. piperita oil also interfered with bacterial quorum sensing communication and did not produce any apparent cell toxicity in immortalized human keratinocytes (HaCaT). M. piperita represented an alternative substance for combating S. mutans and biofilm formation and a potential combination option with chlorhexidine to minimize side effects. An in-situ performance assessment requires further studies.

Potential Probiotic Weizmannia coagulans WC10 Improved Antibiotic-Associated Diarrhea in Mice by Regulating the Gut Microbiota and Metabolic Homeostasis.

Antibiotic-associated diarrhea (AAD) is a common side effect of long-term and heavy antibiotic therapy. Weizmannia coagulans (W. coagulans) is an ideal probiotic because of its high viability, stability, and numerous health benefits to the host. In this study, the strains were first screened for W. coagulans WC10 (WC10) with a high combined ability based on their biological properties of gastrointestinal tolerance, adhesion, and short-chain fatty acid production ability. The effect of WC10 on mice with AAD was further evaluated. The results showed that WC10 was effective in improving the symptoms of AAD, effectively restoring antibiotic-induced weight loss, and reducing diarrhea status score and fecal water content. In addition, WC10 decreased the expression of pro-inflammatory cytokines and increased the expression of anti-inflammatory cytokines, alleviated intestinal tissue damage and inflammation, and improved intestinal epithelial barrier function by decreasing serum levels of enterotoxin, DAO, and D-lactic acid, and by increasing the expression of the intestinal mucosal immune factors sIgA and occludin. Importantly, the composition and function of the gut microbiota gradually recovered after WC10 treatment, increasing the number of SCFAs-producing Bifidobacterium and Roseburia. Subsequently, the short-chain fatty acid (SCFA) content was examined and WC10 significantly increased acetate, propionate, and butyrate production. Additionally, metabolomic analysis also showed that WC10 reversed the antibiotic interference with major metabolic pathways. These findings provide a solid scientific basis for the future application of W. coagulans WC10 in the treatment of AAD.

Isolation and Identification of Chicken-Derived Lactic Acid Bacteria: In Vitro Probiotic Properties and Antagonistic Effects against Salmonella pullorum, Staphylococcus aureus, and Escherichia coli.

The development of probiotics capable of quickly colonizing the intestines of animals is important in promoting the healthy growth of livestock. The aim of this study was to screen lactic acid bacteria (LAB) from the intestinal microbiota of chickens with potential applications, and to evaluate their probiotic properties and antagonistic abilities against Salmonella pullorum, Staphylococcus aureus, and Escherichia coli. The results showed that a total of 79 strains with the characteristics of LAB were isolated from the chicken cecum microbiota, of which 7 strains exhibited strong inhibitory activity against S. pullorum, S. aureus, and E. coli. Performing 16s rDNA sequencing revealed that these seven strains were Lactiplantibacillus pentosus (n = 1), Lactiplantibacillus plantarum (n = 3), Lactiplantibacillus paraplantarum (n = 1), Lactiplantibacillus argentoratensis (n = 1), and Lactiplantibacillus fabifermentans (n = 1). Among them, L. pentosus R26 and L. plantarum R32 exhibited superior antibacterial activity. These two strains demonstrated high lactic acid production ability, with survival rates of 86.29% and 87.99% after 3 h of treatment at pH 1.5, 86.66% and 85.52% after 3 h of treatment with 0.5% bile salts, 90.03% and 88.16% after 2 h of treatment with simulated gastric fluid, and 98.92% and 98.22% after 2 h of treatment with simulated intestinal fluid, respectively. Co-cultivation with L. pentosus R26 for 24 h resulted in 50% of the pathogens being antagonized, while almost complete inhibition was observed following 72 h of co-cultivation. In conclusion, L. pentosus R26 and L. plantarum R32 exhibited high antibacterial activity and acid production capability, while also demonstrating satisfactory tolerance to low pH values and high concentrations of bile salts and digestive fluid. The probiotic characteristics and stress resistance of L. pentosus R26 were slightly superior to those of L. plantarum R32, indicating its potential for development as a probiotic.

Effects of complex polysaccharides by Ficus carica Linn. polysaccharide and peach gum on the development and metabolites of human gut microbiota

Both Ficus carica Linn. polysaccharide and peach gum had beneficial effects on human gut microbiota. However, their complex polysaccharides have never been studied during the fecal fermentation in vitro. Therefore, this study investigated the effects of Ficus carica Linn. polysaccharide (FCPS), peach gum polysaccharide (PGPS) and their complex polysaccharides on fecal fermentation characteristics and gut microbiota composition in vitro. The changes of pH, gas production and short-chain fatty acids (SCFAs) in the metabolites were measured at 0, 6, 9, 12 and 24 h under anaerobic conditions. The changes of gut microbiota were measured at 24 h. The results of metabolite determination showed that FCPS and FCPG2_1 had strong acid production, pH reduction and gas production ability, while the PGPS had poor effect. The results of gut microbiota analysis showed that Firmicutes, Bacteroidetes and Proteobacteria were the dominant phyla in the fermentation process, and the ratio of Firmicutes to Bacteroidetes was the lowest in the FCPG1_1. At the genus level, the promoting effects of these five polysaccharides on different genera were different. FCPS notably augmented the proliferation of Bacteroides and Phascolarctobacterium. Similarly, FCPG1_1 significantly enhanced the growth of Faecalibacterium and Paraprevotella. Furthermore, FCPG2_1 was responsible for an upsurge in the proliferation of the Lachnospiraceae_NK4A136_group, whereas PGPS proved excellent in stimulating Roseburia's growth. In summary, complex polysaccharides and FCPS were better, and they had potential anti-obesity effects. This study had practical significance for the development of functional food and dietary intervention.

Fluoride-resistant Streptococcus mutans within cross-kingdom biofilms support Candida albicans growth under fluoride and attenuate the in vitro anti-caries effect of fluorine.

Fluoride-resistant Streptococcus mutans (S. mutans) might affect the ecological balance of biofilms in the presence of fluoride. We used a S. mutans and Candida albicans (C. albicans) cross-kingdom biofilm model to investigate whether fluoride-resistant S. mutans in biofilms would support C. albicans growth under fluoride stress and attenuate the in vitro anti-caries effect of fluorine. The impact of fluoride-resistant S. mutans on formation of cross-kingdom biofilms by S. mutans and C. albicans in the presence of fluoride was investigated in vitro using the crystal violet staining assay. Biofilm constitution was determined using colony-forming unit (CFU) counts and fluorescent in situ hybridization (FISH). Extracellular polysaccharide (EPS) generation in biofilms was determined by EPS/bacterial dying and water-insoluble polysaccharide detection. Acid production and demineralization were monitored using pH, lactic acid content, and transversal microradiography (TMR). The gene expression of microorganisms in the cross-kingdom biofilm was measured using qRT-PCR. Our results showed that both C. albicans and fluoride-resistant S. mutans grew vigorously, forming robust cross-kingdom biofilms, even in the presence of sodium fluoride (NaF). Moreover, fluoride-resistant S. mutans-containing cross-kingdom biofilms had considerable cariogenic potential for EPS synthesis, acid production, and demineralization ability in the presence of NaF than fluoride-sensitive S. mutans-containing biofilms. Furthermore, the gene expression of microorganisms in the two cross-kingdom biofilms changed dissimilarly in the presence of NaF. In summary, fluoride-resistant S. mutans in cross-kingdom biofilms supported C. albicans growth under fluoride and might attenuate the anti-caries potential of fluorine by maintaining robust cross-kingdom biofilm formation and cariogenic virulence expression in vitro in the presence of NaF.

Uncovering the mechanism of Clostridium butyricum CBX 2021 to improve pig health based on in vivo and in vitro studies.

As a symbiotic probiotic for the host, Clostridium butyricum (CB) has the potential to strengthen the body's immune system and improve intestinal health. However, the probiotic mechanism of CB is not completely understood. The Clostridium butyricum CBX 2021 strain isolated by our team from a health pig independently exhibits strong butyric acid production ability and stress resistance. Therefore, this study comprehensively investigated the efficacy of CBX 2021 in pigs and its mechanism of improving pig health. In this study, we systematically revealed the probiotic effect and potential mechanism of the strain by using various methods such as microbiome, metabolites and transcriptome through animal experiments in vivo and cell experiments in vitro. Our in vivo study showed that CBX 2021 improved growth indicators such as daily weight gain in weaned piglets and also reduced diarrhea rates. Meanwhile, CBX 2021 significantly increased immunoglobulin levels in piglets, reduced contents of inflammatory factors and improved the intestinal barrier. Subsequently, 16S rRNA sequencing showed that CBX 2021 treatment implanted more butyric acid-producing bacteria (such as Faecalibacterium) in piglets and reduced the number of potentially pathogenic bacteria (like Rikenellaceae RC9_gut_group). With significant changes in the microbial community, CBX 2021 improved tryptophan metabolism and several alkaloids synthesis in piglets. Further in vitro experiments showed that CBX 2021 adhesion directly promoted the proliferation of a porcine intestinal epithelial cell line (IPEC-J2). Moreover, transcriptome analysis revealed that bacterial adhesion increased the expression of intracellular G protein-coupled receptors, inhibited the Notch signaling pathway, and led to a decrease in intracellular pro-inflammatory molecules. These results suggest that CBX 2021 may accelerate piglet growth by optimizing the intestinal microbiota, improving metabolic function and enhancing intestinal health.

Homofermentative Lactobacilli isolated from organic sources exhibit potential ability of lactic acid production.

There has been an increasing interest in recent years in lactic acid bacteria that are derived from organic sources for lactic acid production. This research article presents the isolation and identification of homofermentative lactic acid bacteria from various novel organic sources, followed by qualitative and quantitative analyses of lactic acid produced. A total of 32 isolates were identified initially from various sources, such as curd (C1, C2), probiotics (P1, P2, and P3), silage (Si1 and Si2), soil samples (S1, S2, and S3), vermicompost (V1 and V2), and Farmyard manure. Biochemical tests such as Gram's staining, catalase test, and oxidase test were conducted for preliminary identification of lactic acid bacteria using De Man, Rogosa, and Sharpe agar (MRS) media. Through selection and identification, based on colony morphology and biochemical characteristics, 18 isolates were identified as lactic acid bacteria. The subsequent analysis included a tube test, screening for organic acid production, and homofermentative screening using homofermentative-heterofermentative differential (HHD) medium for qualitative analysis of lactic acid. The results revealed that 9 out of 18 selected strains were homofermentative and had promising potential for the production of lactic acid. Furthermore, six isolates (P1-1, S1-3, C2-1, V2-3, P2-1, and C1-1) from all of the nine positive strains were subjected to pH testing (0, 24, 48, and 72 h) and titrimetric assay for estimation of % crude lactic acid present. The presence of lactic acid was confirmed using thin-layer chromatography (TLC). L (+)-Lactic acid was quantified using a K-LATE enzymatic assay kit, for the best three isolates (P1-1, S1-3, C2-1). Finally, the strains were subjected to 16SrRNA sequencing and were identified as Lactobacilli. Based on the findings of the study, it could be concluded that homofermentative lactic acid bacteria with significant LA-producing ability can be obtained from different organic sources and may prove to be useful in the successful production of lactic acid for biotechnological applications.

Enhancing the highland barley-wheat dough network structure and bread quality using freeze-dried sourdough powder with inulin as a protectant

In this study, freeze-dried highland barley sourdough powder containing inulin (SPN) was prepared, and its stability during storage, as well as the effects of SPN on dough network structure and bread quality, were investigated. Results showed that SPN retained a higher number of viable lactic acid bacteria and acid-producing ability in comparison to sourdough powder without inulin when stored at 4 °C for 60 d. The use of SPN was advantageous in the formation of gluten network structure in the dough. Bread prepared with SPN (B2) exhibited a larger specific volume and a softer texture than the highland barley-wheat (1:8, w/w) bread prepared without sourdough (B0) (P < 0.05) and the one prepared with fresh highland barley sourdough (B1) (P > 0.05). Sourdough usage decreased in vitro starch digestibility, yet increased protein digestibility and antioxidant activity, with no significant differences between B1 and B2. Ultimately, B2 showed the highest overall acceptability. The positive effects of SPN may provide insights into future innovations in this area.

Isolation and functional analysis of acid-producing bacteria from bovine rumen.

Ruminants such as cattle rely mainly on microbes in the rumen to digest cellulose and hemicellulose from forage, and the digestion products are mainly absorbed and utilized by the host in the form of short chain fatty acids (SCFAs). This study aimed to isolate acid-producing strains from the cattle rumen and investigate their functions. A total of 980 strains of acid-producing bacteria were isolated from cattle rumen contents using a medium supplemented with bromocresol green. Combined with the test of acid production ability and 16S rRNA amplicon sequencing technology, five strains were selected based on their ability to produce relatively high levels of acid, including Bacillus pumillus, Enterococcus hirae, Enterococcus faecium, and Bacillus subtilis. Sheep were treated by gavage with a mixed bacterial suspension. The results showed that mixed bacteria significantly increased the body weight gain and feed conversion rate of sheep. To investigate the function of acid-producing bacteria in sheep, we used 16S rDNA sequencing technology to analyze the rumen microbes of sheep. We found that mixed bacteria changed the composition and abundance of sheep rumen bacteria. Among them, the abundance of Bacteroidota, Actinobacteriota, Acidobacteriota, and Proteobacteria was significantly increased, and the abundance of Firmicutes was significantly decreased, indicating that the changes in gut microbiota changed the function of the sheep rumen. The acid-producing bacteria isolated in this study can effectively promote the growth of ruminants, such as cattle and sheep, and can be used as additives to improve breeding efficiency, which lays a foundation for subsequent research on probiotics.

Brewing-related genes annotation of Bacillus velezensis CS1.10S isolated from traditional moromi and its effects on promoting soy sauce fermentation

The abundance of salt-tolerant microorganisms in moromi contributes greatly to the flavor of soy sauce, and Bacillus velezensis CS1.10S, isolated from the traditional Chinese sun-brewed moromi, is one of them. In order to understand the intrinsic mechanism of the fermentation properties of this bacterium, 4211 genes obtained from the sequencing of its genome were annotated, and it was found that genes encoding carbohydrate metabolism and transport accounted for 7.43%. Genes encoding amino acid metabolism and transport accounted for 9.66%, with a total of 284 genes related to amino acid synthesis, and 13 metabolic pathways covering 19 amino acids, which showed that CS1.10S had good carbon and nitrogen metabolism and amino acid production ability. KEGG also annotated three kinds of salt tolerance-related genes, which explained the good performance of CS1.10S in tolerating salt up to 160 g/L. A comparative study of the quality indexes of fermented soy sauce supplemented with CS1.10S revealed that the amino acid nitrogen content of soy sauce supplemented with CS1.10S on the 10th day of fermentation was 7.51% higher than that of the control group, and its total free amino acid content also increased by 42.38%. The contents of reducing sugars and volatile flavor compounds also increased, but the total acid did not change much, indicating that CS1.10S was beneficial to the taste and aroma of soy sauce. The annotation of CS1.10S with brewing-related genes and the corresponding evidence from fermentation tests indicated that CS1.10S has the potential to improve the flavor of soy sauce.

Isolation of Limosilactobacillus reuteri Strain with Anti-porcine Epidemic Diarrhea Virus from Swine Feces.

Porcine epidemic diarrhea virus (PEDV) causes severe diarrhea diseases in piglets, which has brought huge economic losses to the pig industry. As the dominant Lactobacillus species in the piglet intestine, the antiviral effect of Limosilactobacillus reuteri (L. reuteri) has been reported. Nine L. reuteri strains were isolated and identified from swine feces in this study. The CCK-8 assay examined the anti-PEDV potential of their cell-free supernatant (CFS). Among the nine L. reuteri isolates examined, LRC8 had a higher inhibition rate to PEDV than the other strains. Thus, the biological properties of the LRC8 strain, such as growth ability, acid production ability, acid and bile salt tolerance, and adhesion to IPEC-J2 cells, were evaluated. Besides, the anti-PEDV activity of LRC8-CFS (LRC8 metabolites, LRM) was assessed using plaque reduction assays, indirect immunofluorescence assays, RT-qPCR, and western blotting. The mRNA relative expression levels of inflammatory factors including IL-1β, IL-6, IL-8, MCP1, and TNF-α were determined by RT-qPCR. The results showed that the LRC8 strain grew well, was resistant to acid, tolerated bile salts, and adhered strongly to IPEC-J2 cells. In addition, treatment with its CFS (LRM) dramatically downregulated the mRNA expression levels of inflammatory cytokines, and in the Vero cell culture, prophylactic, therapeutic, competitive, and direct-inhibitory actions were seen against PEDV. Finally, we explored the anti-PEDV effects of the LRC8 strain in piglets and found that the LRC8 strain effectively relieved the clinical symptoms and intestinal damage of piglets infected by PEDV. To sum up, we found a L. reuteri strain with an anti-PEDV effect.

Biodiversity of Endophytic Microbes in Diverse Tea Chrysanthemum Cultivars and Their Potential Promoting Effects on Plant Growth and Quality.

The endophytic microbiomes significantly differed across tea chrysanthemum cultivars and organs (stems and leaves). The most abundant endophytic bacterial genera were Pseudomonas, Masillia, and Enterobacter in the leaves and Sphingomonas and Curtobacterium in the stems of the five cultivars. Meanwhile, the most abundant endophytic fungal genera in the leaves and stems of the five tea chrysanthemums were Alternaria, Cladosporium, and Sporobolomyces. Specifically, Rhodotorula was dominant in the leaves of 'Jinsi huangjv' and Paraphoma was dominant in the stems of 'Jinsi huangjv'. In all cultivars, the diversity and richness of endophytic bacteria were higher in leaves than in stems (p < 0.05). The highest diversity and richness of endophytic bacteria were recorded in 'Chujv', followed by 'Jinsi huangjv', 'Fubai jv', 'Nannong jinjv', and 'Hangbai jv'. Meanwhile, endophytic fungi were less pronounced. Twenty-seven and 15 cultivable endophytic bacteria and fungi were isolated, four isolated endophytic bacteria, namely, CJY1 (Bacillus oryzaecorticis), CY2 (Pseudomonas psychrotolerans), JSJ7, and JSJ17 (Enterobacter cloacae) showed higher indole acetic acid production ability. Further field studies indicated that inoculation of these four endophytic bacteria not only promoted plant growth and yield but also increased total flavonoids, chlorogenic acid, luteolin, and 3,5-dicoffeylquinic acid levels in the dry flowers of tea chrysanthemums.

Effects of Lactobacillus fermentum GD01 fermentation on the nutritional components and flavor substances of three kinds of bean milk

This study investigated the effects of lactic acid bacteria fermentation on the nutritional components of soy milk, peanut milk and chickpea milk. The results showed that L. fermentum GD01 grew well and had a high acid-producing ability in bean milk. The fermentation with L. fermentum GD01 reduced the content of soluble protein and sugar in bean milk while increased some other bioactive substances, such as polypeptides, amino acids, polyphenols, and flavonoids. Therefore, this fermentation could improve the nutritional value of the bean milk. Furthermore, the types and contents of volatile flavor compounds in bean milk were altered by fermentation. The rise in organic acids, alcohols, and esters, as well as the reduction in aldehydes, diminished the beany flavor and enhanced aroma of bean milk. Our findings would provide a theoretical basis for the production of fermented bean milk with high functional and nutritional value by using lactic acid bacteria.

Effects of Nitrogen Sources and Inorganic Salts on Antioxidant Activity of Goat Milk Fermented by Lactobacillus plantarum L60

Abstract This study investigated the effects of various nitrogen sources (peptone, casein hydrolysate) and inorganic salts (KH2PO4, MgSO4 and NaCl) on the antioxidant activity (specifically, DPPH and superoxide anion scavenging rate), acidity, and pH of peptides in goat milk (GM) fermented by Lactobacillus plantarum L60 by individual factor experiments. The results indicated that nitrogen sources and inorganic salts significantly affected L. plantarum L60’s antioxidant and acid-producing abilities, and when the supplemental levels of peptone, casein hydrolysate, KH2PO4, MgSO4 and NaCl were 0.7%, 0.3%, 0.3%, 0.15% and 0.9%, respectively, the scavenging ability of antioxidant peptides on DPPH radical and superoxide anion reached the maximum.