Journal of microbiology and biotechnology最新文献

Currently, Fragaria ananassa Duch. are discarded as by-products except for the fruit part, so we developed a natural material using the top (= calyx), one of the by-products, and prepared an extract using 70% ethanol to investigate its effects on anti-inflammatory mechanisms. The polyphenol content of 70% ethanol extracts from Fragaria ananassa Duch. calyx was measured to be 265.86 ± 0.85 mg TAE/100 g, respectively. The antioxidant activity was confirmed through the electron donating ability and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging ability measurements. When extracts from Fragaria ananassa Duch. calyx was treated to LPS-induced RAW 264.7 cells, it was confirmed that the production of inflammation-related factors, NO, PGE₂, iNOS, COX-2, TNF-a, and IL-6, was inhibited. In addition, it was confirmed that extracts from Fragaria ananassa Duch. calyx affected the MAPK signaling pathway by reducing the protein expression of p-ERK, p-JNK, and p-p38, which are the upper signaling pathways. In addition, it was confirmed to reduce the protein expression of p-p65 and p-IκB, which are NF-κB signaling pathways. Therefore, this study suggests that extracts from Fragaria ananassa Duch. calyx affect the regulation of the production of major inflammation-related factors by inhibiting the MAPK and NF-κB signaling pathway. These results confirmed that extracts from Fragaria ananassa Duch. calyx have the potential to be developed as a new natural material with anti-inflammatory activity.

Yeast protein, high-quality and high-content microbial protein, can serve as alternative sources of protein. This study examined the structural and functional characteristics of yeast protein through enzymatic treatment using different ratios of alcalase (endo-type) and prozyme 2000P (exo-type) including 2:1 (A2P1), 1:1 (A1P1), and 1:2 (A1P2). After enzymatic hydrolysis, a significant increase in protein solubility from less than 3.1% in untreated proteins to around 16%, particularly at pH 2 or pH 12. Furthermore, a maximum degree of hydrolysis of over 85% was achieved after enzyme treatment. Among them, the highest value of 87.73% was achieved at yeast protein treated by A1P2. Scanning electron microscopy images revealed varied surface morphologies, with exhibiting an increased surface area, particularly after treatment using A2P1. Next, yeast protein treated with A2P1 also demonstrated a superior emulsion stability index (3364.17). However, the antioxidant capacity was higher in proteins treated with A1P2 (78.30%). In addition, the elevated levels of certain amino acids, specifically leucine, lysine, phenylalanine, valine, and arginine, thereby indicating an enhanced amino acid profile was observed. Overall, yeast proteins treated with complex enzymes exhibited improved functionality and potential for diverse food applications.

Postbiotics, bioactive compounds from the fermentation process by probiotics, are gaining attention for their potential health benefits as safer alternatives to live probiotic microbes. Lactiplantibacillus plantarum is a well-studied probiotic species known for promoting gut health and immune modulation. However, the safety and effects of its postbiotic formulations on the gut microbiome structure remain less explored. This study presents a randomized, double-blind, placebo-controlled human study of KLP-KM2, a postbiotic consisting of heat-treated L. plantarum KM2 fermentation complex, in elderly participants. Over 12 weeks, KLP-KM2 consumption did not result in noticeable adverse reaction cases compared to the placebo. Nevertheless, the gut microbial diversity and taxonomic architecture of the KLP-KM2 recipients were differentiated from those of the placebo recipients after 12 weeks. A notable outcome was the increase in the number of subjects carrying Veillonella spp., which contributed to the distinct gut microbiome profiles observed between the two groups. Interestingly, KLP-KM2 facilitated the de novo colonization of Veillonella spp. in subjects who had not harbored these bacteria at the baseline. These results suggest the potential of KLP-KM2 as a safe and effective postbiotic intervention to enhance energy metabolism and mobility in older adults.

Endosymbionts are important for insect species as they provide essential substances to the host. Due to the technical advance of NGS technology and de novo assemblers, many endosymbionts bacterial genomes are available now. Here, we analysed fourteen endosymbiont bacterial genomes of Aphis genius, one of notorious pest species. Fourteen genomes displayed the length between 628,098 bp to 634,931 bp; GC ratio was from 24.2 % to 25.6 % with no structural variation found. The nucleotide diversity distribution across the 14 endosymbiont genomes revealed three distinct regions, each separated by varying levels of nucleotide diversity. Intraspecific variations identified from endosymbiont bacterial genomes of the same host species revealed numbers of SNPs ranging from 31 (0.0049%) to 1,652 (0.26%) and those of INDELs ranging from 7 (21 bp; 0.0033%) to 104 (285 bp; 0.0045%). 250 unique SSRs, 28 different common SSR groups, and one different SSR group in two genomes were identified and used as a potential molecular marker to distinguish intraspecific population. Phylogenetic analysis further showed congruence between the endosymbiont bacterial genomes and the host species phylogeny, except Aphis nasturtii, Aphis helianth, and Aphis auranti, which require additional endosymbiont genomes for clarification. This comparative analysis result could serve as a cornerstone for understanding the relationship between host and endosymbiont species from a genomic perspective.

Extracellular vesicles (EVs) have garnered attention in research for their potential as biochemical transporters and immune modulators, crucial for regulating the host immune system. The present study was conducted to isolate and characterize EVs from Gram negative bacteria Edwardsiella piscicida (EpEVs) and investigate their proteomic profile and immune responses. Isolation of EpEVs was carried out using ultracentrifugation method. Transmission electron microscopy results confirmed the spherical shape of EpEVs. The average size and zeta potential were 85.3 ± 1.8 nm and -8.28 ± 0.41 mV, respectively. EpEVs consisted of 1,487 distinct proteins. Subcellular localization analysis revealed that "cell" and "cell part" were the most predominant areas for protein localization. Proteins associated with virulence, along with several chaperones that facilitate protein folding and stability, were also present. No toxicity was detected when EpEVs were treated to fathead minnow (FHM) cells up to 100 μg/ml. Fluorescent-labeled EpEVs showed cellular internalization in FHM cells at 24 h post treatment (hpt). In-vitro gene expression in Raw 264.7 cells showed upregulation of interleukin (Il)6, Il1β, and interferon (Ifn)β with simultaneous upregulation of anti-inflammatory Il10. In vivo, gene expression revealed that except for heat shock protein (hsp)70, all other genes were upregulated suggesting that EpEVs induced the expression of immune-related genes. Western blot analysis showed increased protein levels of tumor necrosis factor (Tnf)α in EpEVs-treated spleen tissue of zebrafish. Our results confirm that EpEVs can be successfully isolated using the ultracentrifugation method. Furthermore, exploring immunomodulatory mechanism of EpEVs is essential for their potential use as novel therapeutics in fish medicine.

Probiotics are in high demand in the health functional food market as they effectively inhibit pathogens and improve host health. Therefore, in order to develop novel probiotic strains, new strains were isolated from various type of jeotgal, traditional Korean fermented seafood products, and their safety and probiotic properties have been evaluated. Based on 16S rRNA gene sequence analysis, six strains (JRD1, Pediococcus pentosaceus; JRD2, Lactiplantibacillus plantarum; JRD6, Pediococcus acidilactici; CLJ21, Lactiplantibacillus plantarum; CLJ24, Pediococcus pentosaceus; CLJ28, Leuconostoc mesenteroides subsp. dextranicum) were selected and subjected to further analysis. As a result, all six strains did not show hemolytic activity, antibiotics resistance, and cell cytotoxicity, confirming that they are safe for human use. Among them, JRD1, JRD6, and CLJ24 exhibited high survival rates under simulated gastrointestinal conditions. Additionally, these three strains demonstrated strong adhesion abilities on HT-29 cells, with values of 6.02, 5.77, and 5.86 log CFU/mL, respectively. Furthermore, JRD1, JRD6, and CLJ24 showed relatively high antagonistic activity against both Salmonella Typhimurium and Staphylococcus aureus through competition, exclusion, and displacement of their adhesion. Interestingly, cell-free supernatants (CFS) from three strains effectively inhibited the growth of both S. Typhimurium and S. aureus. Furthermore, CFS of CLJ24, JRD1, and JRD6 demonstrated anti-inflammatory effects in intestinal epithelial cells. The results suggest that CLJ24, JRD1, and JRD6 have potential to be development as functional probiotic strains with both antibacterial and anti-inflammatory activities.

Morinda citrifolia L. (noni) is native to the tropical and semitropical areas and has been commercially available in health food stores and chain grocery stores specializing in natural foods, recently. Noni seeds are discarded as waste products through the industrial production of noni juice even though their bioactivity components might be a potential source of functional foods. Not many studies of phytochemistry and biological activity have been investigated on noni seeds until now. In this study, the phytochemical investigation of M. citrifolia seeds led to the isolation of eight compounds (1-8) including four lignans (5-8). Their chemical structures were elucidated based on extensive spectroscopic analysis as well as the comparison with those reported in the literature. The isolated lignans were then evaluated for their anti-inflammatory activity by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphynyltetrazolium bromide (MTT) assay in human bronchial epithelium BEAS-2B cells stimulated by 1-nitropyrene. As results, both four isolated lignans displayed high effects on the viability of BEAS-2B cells, indicating promising anti-inflammatory role in the airway disease.

Nypa fruticans Wurmb is known to contain large amounts of polyphenols and flavonoids with antioxidative and anti-inflammatory effects. However, the biological and physiological functions of N. fruticans have not been scientifically investigated. Thus, we investigated the immunomodulatory effect of N. fruticans hot water extract (YSK-N) in mice using an immune compromised model established by forced swimming (FS). Intensive exercise decreased body weight, organ index, and various immunological parameters in FS mice. However, oral administration of YSK-N significantly restored the FS-induced decreases in body, thymus, and spleen weights, as well as the reduction in the numbers of white blood cells and lymphocytes in the whole blood of mice. Additionally, YSK-N increased splenic cell proliferation in the absence and presence of concanavalin A or lipopolysaccharide stimulation in a concentration-dependent manner. Notably, YSK-N enhanced the cytotoxic activity of natural killer cells against YAC-1 tumor cells under immunosuppressive conditions. Furthermore, YSK-N supplementation reverted the FS-induced downregulation in immunoglobulin production and Il2, Il6, Il12, Ifnγ, Gzmb, and Prf1 mRNA expression. Therefore, our observations suggested that YSK-N promotes immune function and has potential as an immunomodulatory agent.

Inflammatory is a crucial part of the immune system of body protect it from harmful invaders, such as bacteria, viruses, and other foreign substances. In this study, the effects of chloroform extract of fermented Viola mandshurica (CEFV) on lipopolysaccharide (LPS)-induced inflammatory response in RAW264.7 macrophages were investigated. The CEFV significantly inhibited NO production and reduced the expression of inducible nitric oxide synthase (iNOS) at both protein and mRNA levels in a dose-dependent manner. Also, CEFV decreased PGE2 production, suppressed COX-2 expression, and inhibited the activation of the ERK and JNK pathways but not the p38 pathway. Taken together, CEFV suppressed NF-κB activation, which is a key regulator in the inflammatory response. The main phenolic compounds identified in CEFV were tectoridin, luteolin, resveratrol, and hesperetin. Therefore, in this study, CEFC exhibits potent anti-inflammatory effects by downregulating the production of pro-inflammatory mediators and inhibiting key inflammatory pathway in RAW264.7 cells.

Gamma-aminobutyric acid (GABA), a non-proteinogenic amino acid, exhibits diverse physiological functions and finds extensive applications in food, medicine, and various industries. Glutamate decarboxylase (GAD) can effectively convert L-glutamic acid (L-Glu) or monosodium glutamate (MSG) into GABA. However, the low food-grade expression of GAD has hindered large-scale GABA production. In this study, we aimed to elevate GAD expression in Bacillus subtilis through cofactor synthesis enhancement, CRISPRi-based host strain modification, and fermentation optimization. In a 3-L fermenter, the optimized strain achieved a remarkable GAD activity of 319.62 U/ml without antibiotic selection pressure, representing the highest reported food-grade expression to date. Subsequently, enzymatic property analysis facilitated the optimization of GABA production using MSG and L-Glu as substrates, achieving 100% molar conversion yields of 274.40 g/l and 481.62 g/l, respectively, with the latter yielding an unprecedented productivity of 48.16 g/l/h. Finally, in vitro fermentation demonstrated that GABA supplementation promoted gut microbial growth and increased the relative abundance of Actinobacteriota and Bacteroidota.