Lactobacillus sakei MJM60958 as a Potential Probiotic Alleviated Non-Alcoholic Fatty Liver Disease in Mice Fed a High-Fat Diet by Modulating Lipid Metabolism,Inflammation, and Gut Microbiota

Non-alcoholic fatty liver disease (NAFLD) is a common liver disease with a rapidly increasing number of cases worldwide. This study aimed to evaluate the effects of Lactobacillus sakei MJM60958 (MJM60958) on NAFLD in vitro and in vivo. In in vitro tests, MJM60958 significantly inhibited lipid accumulation by 46.79% in HepG2 cells stimulated with oleic acid and cholesterol (OA-C). Moreover, MJM60958 showed safe and probiotic characteristics in vitro. In the animal study, MJM60958 administration in a high-fat diet-induced NAFLD mouse model significantly reduced body weight and liver weight, and controlled aspartate aminotransferase (ALT), aspartate transaminase (AST), triglyceride (TG), urea nitrogen (BUN), and uric acid (UA) levels in the blood, which are features of NAFLD. Further, treatment with MJM60958 also reduced steatosis scores in liver tissues, serum leptin and interleukin, and increased serum adiponectin content. Moreover, administration of MJM60958 resulted in a significantly decreased expression of some genes and proteins which are related to lipid accumulation, such as fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), and sterol regulatory element-binding protein 1 (SREBP-1), and also upregulated genes and protein expression of lipid oxidation such as peroxisome proliferator-activated receptor alpha (PPARα) and carnitine palmitoyltransferase 1a (CPT1A). Administration of MJM60958 increased the relative abundance of specific microbial taxa such as Verrucomicrobia, which are abundant in non-NAFLD mice, and reduced Firmicutes, which are a major group in NAFLD mice. MJM60958 affected the modulation of gut microbiota and altered the strain profile of short-chain fatty acids (SCFAs) production in the cecum by reduced lactic acid and enhanced acetic acid production. Overall, MJM60958 showed potential as a probiotic that can prevent and treat NAFLD.     

Rapid Proteomic Characterization of Bacteriocin-Producing Enterococcus faecium Strains from Foodstuffs

Enterococcus belongs to a group of microorganisms known as lactic acid bacteria (LAB), which constitute a broad heterogeneous group of generally food-grade microorganisms historically used in food preservation. Enterococci live as commensals of the gastrointestinal tract of warm-blooded animals, although they also are present in food of animal origin (milk, cheese, fermented sausages), vegetables, and plant materials because of their ability to survive heat treatments and adverse environmental conditions. The biotechnological traits of enterococci can be applied in the food industry; however, the emergence of enterococci as a cause of nosocomial infections makes their food status uncertain. Recent advances in high-throughput sequencing allow the subtyping of bacterial pathogens, but it cannot reflect the temporal dynamics and functional activities of microbiomes or bacterial isolates. Moreover, genetic analysis is based on sequence homologies, inferring functions from databases. Here, we used an end-to-end proteomic workflow to rapidly characterize two bacteriocin-producing Enterococcus faecium (Efm) strains. The proteome analysis was performed with liquid chromatography coupled to a trapped ion mobility spectrometry-time-of-flight mass spectrometry instrument (TimsTOF) for high-throughput and high-resolution characterization of bacterial proteins. Thus, we identified almost half of the proteins predicted in the bacterial genomes (>1100 unique proteins per isolate), including quantifying proteins conferring resistance to antibiotics, heavy metals, virulence factors, and bacteriocins. The obtained proteomes were annotated according to function, resulting in 22 complete KEGG metabolic pathway modules for both strains. The workflow used here successfully characterized these bacterial isolates and showed great promise for determining and optimizing the bioengineering and biotechnology properties of other LAB strains in the food industry.     

Lactobacillus pentosus MJM60383 Inhibits Lipid Accumulation in Caenorhabditis elegans Induced by Enterobacter cloacae and Glucose

Gut microbiota are known to play an important role in obesity. Enterobacter cloacae, a Gram-negative bacterium, has been considered a pathogenic bacterium related to obesity in the gut. In this study, we established an obesity model of C. elegans by feeding E. cloacae combined with a high glucose diet (HGD), which significantly induced lipid accumulation. An anti-lipid mechanism study revealed that the fatty acid composition and the expression level of fat metabolism-related genes were altered by feeding E. cloacae to C. elegans under HGD conditions. Lactic acid bacteria that showed antagonistic activity against E. cloacae were used to screen anti-obesity candidates in this model. Among them, L. pentosus MJM60383 (MJM60383) showed good antagonistic activity. C. eleans fed with MJM60383 significantly reduced lipid accumulation and triglyceride content. The ratio of C18:1Δ9/C18:0 was also changed in C. elegans by feeding MJM60383. In addition, the expression level of genes related to fatty acid synthesis was significantly decreased and the genes related to fatty acid β-oxidation were up-regulated by feeding MJM60383. Moreover, MJM60383 also exhibited a high adhesive ability to Caco-2 cells and colonized the gut of C. elegans. Thus, L. pentosus MJM60383 can be a promising candidate for anti-obesity probiotics. To the best of our knowledge, this is the first report that uses E. cloacae combined with a high-glucose diet to study the interactions between individual pathogens and probiotics in C. elegans.     

Antioxidant and Antibacterial Effects of Potential Probiotics Isolated from Korean Fermented Foods

A total of sixteen bacterial strains were isolated and identified from the fourteen types of Korean fermented foods that were evaluated for their in vitro probiotic potentials. The results showed the highest survivability for Bacillus sp. compared to Lactobacillus sp. in simulated gastric pH, and it was found to be maximum for B. inaquosorum KNUAS016 (8.25 ± 0.08 log10 CFU/mL) and minimum for L. sakei KNUAS019 (0.8 ± 0.02 log10 CFU/mL) at 3 h of incubation. Furthermore, B. inaquosorum KNUAS016 and L. brevis KNUAS017 also had the highest survival rates of 6.86 ± 0.02 and 5.37 ± 0.01 log10 CFU/mL, respectively, in a simulated intestinal fluid condition at 4 h of incubation. The percentage of autoaggregation at 6 h for L. sakei KNUAS019 (66.55 ± 0.33%), B. tequilensis KNUAS015 (64.56 ± 0.14%), and B. inaquosorum KNUAS016 (61.63 ± 0.19%) was >60%, whereas it was lower for L. brevis KNUAS017 (29.98 ± 0.09%). Additionally, B. subtilis KNUAS003 showed higher coaggregation at 63.84 ± 0.19% while B. proteolyticus KNUAS001 found at 30.02 ± 0.33%. Among them, Lactobacillus sp. showed the best non-hemolytic activity. The highest DPPH and ABTS radical scavenging activity was observed in L. sakei KNUAS019 (58.25% and 71.88%). The cell-free supernatant of Lactobacillus sp. considerably inhibited pathogenic growth, while the cell-free supernatant of Bacillus sp. was moderately inhibited when incubated for 24 h. However, the overall results found that B. subtilis KNUAS003, B. proteolyticus KNUAS012, L. brevis KNUAS017, L. graminis KNUAS018, and L. sakei KNUAS019 were recognized as potential probiotics through different functional and toxicity assessments.     

益生菌缓解肥胖形成相关机制及研究进展

肥胖及相关代谢综合征已成为世界范围内的公共健康问题。研究表明,肠道菌群与肥胖的形成密切相关,肠道菌群失调导致脂代谢紊乱、肠道通透性及氧化应激等改变。益生菌(主要包括乳酸菌和双歧杆菌)是一类能对宿主生理功能产生有益作用的微生物,能在肠道中存活并定殖,改善肠道菌群紊乱,进一步缓解肥胖的形成。本文主要围绕益生菌对肥胖的干预作用及相关机制进行综述,以为肥胖相关的研究提供参考。     

Viability assessment of lactic acid bacteria in commercial dairy products stored at 4 °C using LIVE/DEAD® BacLightTM staining and conventional plate counts

The viability of lactic acid bacteria (LAB) from commercial fermented milks was studied during storage at 4 °C. The enumeration of total viable bacteria was assessed using fluorescence microscopy. Plate counting on selective media was used to enumerate LAB. Using LIVE/DEAD® BacLight^TM viability staining, it was observed that bacterial counts decreased gradually after expiry dates, the number of viable bacteria remaining above 10⁶ bacteria g^?1 for all of the products. Viable cell counts estimated by plating onto selective media were lower than those obtained by direct microscopic counting. The viability of LAB contained in acid products decreased during their storage period at 4 °C. All products contain viable LAB ranging from 10⁸ to 10⁹ bacteria g^?1 and could be considered as probiotic, given that the recommended minimum number of probiotic bacteria in such food products is approximately 10⁷ bacteria mL^?1 product. The number of bifidobacteria in commercial fermented milks declared to contain bifidobacteria varied from 10⁴ to 10⁷ bacteria mL^?1. This study confirms the usefulness of fluorescent techniques for a rapid and accurate evaluation of bacterial viability in probiotic products.     

鳙鱼肠道菌群多样性及潜在益生菌的分离鉴定

该研究利用三代16S rRNA扩增子测序技术分析天然池塘生境鳙鱼肠道菌群特征,并从中分离潜在益生菌。该生境鳙鱼肠道菌群以厚壁菌门（Firmicutes,10.28%）和变形菌门（Proteobacteria,21.47%）为主。在属水平上,以未命名菌属ZOR006（21.63%）、严格梭菌属（Clostridium_sensu_stricto_1,10.84%）、罗姆布茨菌属（Romboutsia,10.34%）、类梭菌属（Paeniclostridium,9.63%）、甲基孢囊菌属（Methylocystis,8.74%）为主。为分离到既有利于营养物质的吸收又能抑制病原微生物的鳙鱼源芽孢杆菌（Bacillus）,对从该生境鳙鱼肠道中分离的菌株进行产酶、抑菌等功能相关益生特性试验。试验共分离出3株细菌,YB6、YB42和YB56,通过菌落形态观察及16S rRNA序列分析,鉴定结果显示其分别为贝莱斯芽孢杆菌（Bacillus velezensis strain）、暹罗芽孢杆菌（Bacillus siamensis strain）和解淀粉酶芽孢杆菌（Bacillus amyloliquefaciens strain）。试验结果表明,3株菌均具有良好的产胞外蛋白酶、淀粉酶、纤维素酶及抑制病原菌的能力,可以作为促消化和病原拮抗益生菌做进一步的研究。     

6种益生菌及其添加方式对发酵米酒品质的影响

目的:探究不同益生菌及其添加方式对米酒制作效果的影响。方法:以糯米为原料,通过外源添加鼠李糖乳杆菌BV-77、发酵乳杆菌TSF-331、唾液乳杆菌AP-32、约氏乳杆菌MH-68、嗜酸乳杆菌TYCA-06、干酪乳杆菌CS-773酿制益生菌米酒,对比只添加糖化酶、同时添加糖化酶和酵母以及添加方式(益生菌麸曲和益生菌菌粉)对米酒酒精度、还原糖、总酸和感官质量的影响。结果:酵母对益生菌米酒的发酵有促进作用,可显著提高米酒酒精度和还原糖含量。利用发酵乳杆菌菌粉同时添加用量为200 U/g的糖化酶和0.04%的酵母,在30℃发酵3 d的米酒发酵效果最佳,酒精度和还原糖含量达到最高,分别为7.20%vol和270.00 mg/mL,总酸含量达到最低,为8.40 mL/L,酿造出的米酒口感较为浓郁。结论:发酵乳杆菌是6种益生菌中最适宜酿造米酒的益生菌。     

后生元的研究进展

益生菌是对宿主健康有益的活性微生物,后生元是对宿主健康有益的无生命微生物和/或其成分.文章结合近年来对后生元的研究成果,综述了后生元在调节免疫、缓减过敏症状、调节胃肠道功能、抗氧化、抗炎症,以及降血糖、预防龋齿、抗肿瘤、降血压等方面的功能特性,同时概述了其可能的作用机制.与活菌相比,后生元具有安全、稳定、易于储运等优势...     

活性酸乳中每种益生菌总数的同时计数法

益生菌酸奶的营养作用和保健功能决定于成品中必须含有一定数量级的活性益生菌数.本实验通过研究分析活性酸奶中嗜热链球菌、保加利亚乳杆菌、嗜酸乳杆菌、双歧杆菌、鼠李糖乳杆菌(LGG菌)、干酪乳杆菌等乳酸菌在BBL.平板培养基上的菌落特征及菌体形态,提出了一种可同时准确计数每种益生菌总数的新方法,该方法可直观地观察到各种益生菌的生长活度,免除了传统方法计数不同益生菌总数要用不同培养基的繁琐,为快速鉴定益生菌酸奶品质好坏和保健功能活性高低提供了检测依据.