Probiotics can regulate gut microbes to maintain human health. However, probiotics are sensitive to environmental conditions, which reduces their survival rates. There are two forms of bacterial cells: single (planktonic) cells and biofilms. Many investigations have verified that biofilm-formed probiotic strains are more resistant to adverse environments than their planktonic counterparts. This study successfully produced high-density probiotic microcapsules in a biofilm state by preparing probiotic cells in biofilm mode and combining them with microencapsulation techniques (>10 log CFU/g). Lactiplantibacillus paraplantarum L-ZS9 was cultured within calcium pectin beads (CPB) to create CPB-Biofilm-situ. Subsequent tolerance experiments revealed that the CPB-Biofilm-situ was highly resistant to acid, the gastrointestinal tract (GIT) environment, and freeze-drying. Furthermore, scanning electron microscopy (SEM) revealed that the cells in CPB-Biofilm-situ displayed a marginalization tendency for the culture. The water content of the beads was approximately 10%, which was deemed acceptable, and the texture characteristics were also determined. The physicochemical properties and structure of the beads were investigated using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). This work is a valuable reference for a new generation of probiotic agents in the biofilm state.

The quality of pickled vegetables is essentially safeguarded through various processing techniques. In this study the effects of high hydrostatic pressure processing (HPP), pasteurization (Pt), nisin, HPP + nisin and Pt + nisin on fermented radishes (Raphanus sativus L.) were compared. The effects of the different treatments on firmness were not immediately apparent, however, the HPP-treated pickles maintained their hardness best during storage. Compared with Pt, the non-thermal treatments were found to have moderate effects on the colors, both immediately after treatment and during storage. Both HPP and Pt reduced microbes, while HPP + nisin completely inactivated bacteria. The activities of polyphenol oxidase (PPO), peroxidase (POD) and pectin methylesterase (PME) were most inactivated via Pt, followed the action of HPP and then by that of the nisin. The sensory evaluation suggested that non-thermal pickled radish might be better accepted by consumers. Moreover, Pt had the strongest ability to reduce oxalic acid and sulfur-containing compounds, while the effects of HPP were relatively moderate, and HPP not only effectively reduced sulfur-containing compounds, but also helped to retain the favorable factors in the pickles. The findings of this study, thus, indicate that HPP could be a promising alternative to traditional pasteurization in the processing and storage of fermented vegetables.

The persistence of Staphylococcus aureus within biofilm can lead to contamination of medical devices and life-threatening infections. Luckily, lactic acid bacteria (LAB) have an inhibitory effect on the growth of these bacteria. This study aims to select LAB strains from fermented vegetables, and analyze their potential inhibition activities against S. aureus. In total, 45 isolates of LAB were successfully isolated from Sichuan pickles, and the CFS of Lactiplantibacillus plantarum LR-14 exerted the strongest inhibitory effect against S. aureus. Moreover, S. aureus cells in planktonic and biofilm states both wrinkled and damaged when treated with the CFS of L. plantarum LR-14. In addition, whole genome sequencing analysis indicates that L. plantarum LR-14 contains various functional genes, including predicted extracellular polysaccharides (EPS) biosynthesis genes, and genes participating in the synthesis and metabolism of fatty acid, implying that L. plantarum LR-14 has the potential to be used as a probiotic with multiple functions.

The use of probiotics has recently become a considerably promising research area. The most advanced fourth-generation probiotics involve beneficial bacteria enclosed in biofilms. However, differences in the effects of probiotics in biofilm and those in planktonic states are, as yet, unclear. In this study, it was ascertained that the biofilm mode of Lactobacillus paraplantarum L-ZS9 had a comparatively higher density and stronger resistance. Untargeted metabolomics analysis suggested a significant distinction between planktonic and biofilm cells, with amino acids and carbohydrate metabolism both more active in the biofilm mode. Furthermore, the in vivo experiment showed that the biofilm strain displayed better immunomodulation activity, which could increase the relative abundance of Lactobacillus in the intestinal microbiota of dogs. The relative abundance of intestinal microbiota participating in carbohydrate metabolism was higher in the biofilm probiotic-treated dogs. Correlation analysis between L-ZS9-producing metabolites, dog intestinal microbiome diversity and dog blood immune indexes (sIgA or IgG) revealed the interaction between these three components, which might explain the mechanisms by which biofilm L-ZS9 regulated the intestinal microbiome and immunity activity of the host, through the production of various metabolites. Findings of this study will, thus, enhance understanding of the beneficial effects of biofilm probiotics, as well as provide references for further investigation.

This study aimed to investigate whether and how pgm,fba,and gap overexpression can affect the stress resistance,adhesiveness,and biofilm formation of Lactobacillus plantarum LR-1.Results showed that the overexpression of the pgm and fba genes enhanced the heat,acid and bile salt resistance,biofilm formation and adhesiveness of L.plantarum LR-1.The transcriptional level of the gap gene had no significant effect on the stress resistance,biofilm formation or adhesiveness.The up-regulation of pgm,fba,and gap increased the transcriptional levels of tuf and luxS in this strain with the first two being more effective than the last one.Furthermore,bioinformatic analyses suggested that pgm and fba could be associated with genes related to multiple pathways.These results provide a new understanding of the role of glycolytic pathway-related genes in regulating the stress resistance,adhesiveness,and biofilm formation of L.plantarum.

为了评价从发酵泡菜中分离得到的植物乳杆菌LR-39对犬的促生长、肠道菌群调节作用,并明确其遗传背景,选取10只3.5月龄的比格犬,分为对照组与试验组,对照组饲喂基础犬粮,试验组在每日饲喂基础犬粮基础上补饲1×109 cfu LR-39,试验期28 d.试验结束时,测定并比较各组平均日增质量、料重比及营养物质消化率等指标差异;对犬肠道菌群进行高通量测序,比较肠道菌群在门、种水平上的相对丰度及特征微生物差异;采用PICRUSt技术,解析并比较肠道微生物功能基因的表达水平差异;对LR-39进行全基因组序列测序,绘制该菌株全基因草图并进行序列COG及CAZy注释分析.结果显示,试验组平均日增质量极显著(P<0.01)高于对照组,粗蛋白、粗脂肪、钙的消化率显著(P<0.05)高于对照组,料重比显著(P<0.05)低于对照组.在门水平上,试验组梭杆菌门(Fusobacteria)(P<0.05)相对丰度显著高于对照组,放线菌门(Actinobacteria)相对丰度显著(P<0.05)低于对照组;效应大小线性判别分析(LEfSe)结果显示,试验组肠道菌群特征菌属是梭杆菌属(Fusobacterium),而对照组特征菌属分别是丹毒丝菌属(Bulleidia)、 链型杆菌属(Catenibacterium)、真杆菌属(Eubacterium)、布劳特氏菌属(Blautia)、粪杆菌属(Faecalibacterium);在种水平上,试验组瑞士乳杆菌(Lactobacillus helveticus)相对丰度极显著(P<0.01)高于对照组.肠道功能基因差异分析表明,试验组细胞内运输、细胞外结构基因表达相对丰度显著高于对照组(P<0.05),次级代谢物基因表达相对丰度显著(P<0.05)低于对照组.全基因组测序结果显示,LR-39菌株全长247554 bp,无质粒,GC含量为44.26％,碳水化合物代谢相关基因丰度最高,氨基酸代谢相关基因其次,而脂代谢相关基因较低,具有一定比例拮抗机制相关基因,酶系主要包括糖苷水解酶、糖基转移酶、碳水化合物酯酶、碳水化合物结合分子、辅助性酶类.综上,LR-39能够促进犬的生长,改变犬肠道菌群结构,调节肠道菌群功能基因表达,具有开发益生菌产品的潜质.

本试验旨在比较被膜态与浮游态植物乳杆菌LR-39对比格犬血清免疫指标及肠道菌群结构的影响.制备被膜态与浮游态植物乳杆菌LR-39,采用平板计数法比较不同生物状态的植物乳杆菌LR-39经酸、胆盐环境处理后的存活率.选取15只3.5月龄比格犬,随机分为被膜组、浮游组及对照组3个组,每组5只.被膜组、浮游组每日早上采食犬粮后分别灌饲被膜态与浮游态植物乳杆菌LR-39菌液1 mL(1×109 CFU/mL),对照组灌饲等体积磷酸盐缓冲液(PBS),连续灌饲28 d.检测血清免疫球蛋白G(IgG)、分泌型免疫球蛋白A(sIgA)、白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)含量,并对肠道菌群进行16S rDNA高通量测序分析.结果表明:1)经酸性和胆盐环境处理后,被膜态植物乳杆菌LR-39存活率显著或极显著高于浮游态植物乳杆菌LR-39(P＜0.05或P＜0.01).2)与对照组相比,被膜组血清IgG和sIgA含量极显著提高(P＜0.01);与浮游组相比,被膜组血清sIgA含量极显著提高(P＜0.01),血清IL-6含量有降低趋势(0.05≤P＜0.10);与对照组相比,浮游组血清IgG、sIgA、IL-6、TNF-α含量无显著差异(P＞0.05).3)α多样性分析显示,与对照组相比,被膜组和浮游组Observed species指数、Chao指数、Ace指数均升高,被膜组Shannon指数升高,Simpson指数下降;浮游组Shannon指数下降,Simpson指数升高.主坐标分析(PCoA)结果显示,3组样本间有明显聚类现象.4)在门水平上,与对照组相比,被膜组肠道厚壁菌门(Firmicutes)相对丰度升高,肠道拟杆菌门(Bacte-roidetes)、梭杆菌门(Fusobacteria)、变形菌门(Proteobacteria)、放线菌门(Actinobacteria)相对丰度降低;浮游组肠道Bacteroidetes、Fusobacteria相对丰度升高,Firmicutes、Actinobacteria相对丰度降低.5)在属水平上,与对照组相比,被膜组肠道双歧杆菌属(Bifidobacterium)、乳杆菌属(Lac-tobacillus)、Allobaculum、消化链球菌属(Peptostreptococcus)相对丰度升高;浮游组肠道Lactoba-cillus、Peptostreptococcus、梭杆菌属(Fusobacterium)、普雷沃菌属(Prevotella)、萨特氏菌属(Sut-terella)相对丰度升高.6)LEfSe分析表明,被膜组优势菌属是Lactobacillus,浮游组优势菌属是Fusobacterium,对照组优势菌属包括柯林斯氏菌属(Collinsella)、链型杆菌属(Catenibacterium)、真杆菌属(Eubacterium).7)Spearman相关性分析显示,血清IgG、sIgA、IL-6、TNF-α含量与肠道富集菌群相对丰度无显著相关性(P＞0.05).由此可见,被膜态与浮游态植物乳杆菌LR-39对犬肠道菌群结构影响不同,被膜态植物乳杆菌LR-39具有更强的耐酸及胆盐能力,可有效调整肠道菌群结构并能提高机体免疫水平.

Traditional Chinese fermented vegetables are a type of brine-salted fermented vegetable product. During the spontaneous fermentation, various compounds are produced, degraded, and converted, influencing the quality of the fermented pickle. To ascertain the effect of different containers on the fermentation process of the pickles, this study investigated the bacterial diversity and the chemical composition characteristics of the pickle (radish) fermented in commonly used containers including glass jars (GL), porcelain jars (PO), and plastic jars (PL). The correlation between chemical compounds and microbial community was further analyzed. The changes in pH values suggested that PL may facilitate the quickest fermentation of the pickles, while the process in PO progressed at the lowest rate. The PL brine samples contained higher levels of lactic acid and threonine, while more abundant volatile chemical compounds were evident in PO. The container materials had no significant influence on the microbial structure, wherein Lactobacillus was the absolute dominant genus in all containers. But container material did have an effect on the abundance of specific genus, such as Lactococcus and Pediococcus. The correlation between these major genera was also analyzed and gene function prediction indicated that the top three pathways were: carbohydrate metabolism, amino acid metabolism, and energy metabolism. Lactobacillus negatively correlated with methionine, tyrosine, lysine, and arginine, but positively correlated with ammonia, and lactic acid and acetic acid both just correlated with Pediococcus. This study provides new insights into the microbiota succession and chemical compounds involved in the vegetable fermentation.

The Sichuan pickles of chili peppers, cowpeas and radishes were separately fermented for 12 days in order to identify the distinct microfloras and their correlations with the metabolites in different products. The chili pickle presented a slow fermentation process, high bacterial diversity within six phyla, and sixteen marker genera. Moreover, free amino acids accumulated in chili pickle and its main volatiles were alcohols and esters. Fast acidification and limited bacterial diversity within three phyla were found in Sichuan cowpea and radish pickles. The cowpea pickle was characterized by Lactobacillus and Pediococcus, as well as alcohols and alkenes. The radish pickle featured Lactococcus and Fructobacillus, as well as sulfides and aldehydes. Correlation analysis indicated that the metabolites, especially volatiles, were closely associated with not only the dominant bacteria but also those in low abundance.