Lactic acid bacteria (LAB) are major probiotics in food supplements. Survival in gastrointestinal (GI) tract is important for the effective use of LAB as probiotics. Bile salt hydrolase (BSH), which catalyzes the conversion of conjugated bile salts into free bile salts, can significantly modulate the gut microbiome. Here, we hypothesize that BSH is important for LAB survival and adhesion in the gut. The aim of this study is to investigate the effect of BSH on the survival of LAB in the GI tract. A panel of bsh genes from murine gut microbiota were amplified, cloned and expressed into Lactobacillus plantarum, which were then administered to mice by gavage. Our data indicated that the survival of BSH-positive L. plantarum was significantly prolonged in the GI tract compared with wild type L. plantarum. Furthermore, BSH-positive strains exhibited increased adhesion to Caco-2 intestinal cells than BSH-deleted L. plantarum. Enhanced adhesion to intestinal cells of BSH positive LAB can therefore be an important criterion for selecting effective probiotic strains in food industry.

Hypercholesterolemia is a major risk factor for cardiovascular diseases worldwide. Healthy intestinal microbiota can contribute to reducing the high cholesterol symptoms by producing bile salt hydrolase (BSH). In this study, recombinant BSH from the strain L. johnsonii 334 with high cholesterol reduction ability was selected to study the cholesterol-lowering mechanism mediated by farnesoid X receptor (FXR) regulation in mice. In the presence of recombinant BSH, mice had a larger bile acid pool. Analysis of individual bile acids revealed that bile acid composition was affected not only by recombinant BSH but also by the modulated gut microbiota. We confirmed a marked reduction in the transcription of FXR and its molecular targets in the ileum and a significant increase in the transcription of cholesterol 7a-hydroxylase (CYP7A1), which resulted in the increased bile acid synthesis and cholesterol-lowering effects. Notably, our work reveals the importance of BSH substrate specificity.

This investigation examined the reduction of pesticide residues on straw inoculated with lactic acid bacteria (LAB) during ensiling. Lactobacillus casei WYS3 was isolated from rice straw that contained pesticide residues. Non-sterilized rice straw, which was inoculated with L. casei WYS3, showed increased removal of chlorpyrifos after ensiling, compared with rice straw that was not inoculated with L. casei WYS3 or sterilized rice straw. In pure culture, these strains can bind chlorpyrifos as indicated by high-performance liquid chromatography analysis. Viable L. casei WYS3 was shown to bind 33.3–42% of exogenously added chlorpyrifos. These results are similar to those of acid-treated cells but less than those of heat-treated cells, which were found to bind 32.0% and 77.2% of the added chlorpyrifos respectively. Furthermore, gas chromatography–mass spectrometry analysis determined that L. casei WYS3 detoxified chlorpyrifos via P-O-C cleavage. Real-time polymerized chain reaction analysis determined that organophosphorus hydrolase gene expression tripled after the addition of chlorpyrifos to LAB cultures, compared with the control group (without chlorpyrifos). This paper highlights the potential use of LAB starter cultures for the detoxification and removal of chlorpyrifos residues in the environment.

The inulin-type fructans in Jerusalem artichoke (Helianthus tuberosus L.) tubers exhibit different degrees of polymerization and are critical for germination. We aimed to characterize the sugar metabolism dynamics in the tubers without bud eyes or shoots (T) and BE/S of indoor- and field-grown Jerusalem artichokes during germination. Ht1-FEH II and Ht1-FEH III (1-fructan exohydrolases II and III, inulin-degrading enzymes) expression increased 5 days after planting indoors, whereas Ht1-FEH II expression increased 72 days after planting in the field in T and BE/S. Ht1-SST (sucrose:sucrose 1-fructosyl transferase, inulin synthesis initiator), and Ht1-FFT (fructan:fructan 1-fructosyl transferase, inulin elongator) expression generally decreased in indoor-grown T. The enzyme activities of 1-FEH and 1-FFT were unchanged during germination in both indoor- and field-grown T and BE/S, whereas 1-SST activity decreased in indoor-grown T, while 1-FEH and 1-FFT activities increased as a function of germination time in BE/S of both indoor- and field-grown tubers. The total soluble sugar content gradually decreased in T after germination indoors or in the field, while at the end of germination, the sucrose and fructan contents decreased, and fructose content increased in the field. The enzyme activities of soluble vacuolar (VI) or neutral invertase (NI) did not change significantly, except at the late germination stage. Sucrose synthase (SS) and sucrose-phosphate synthase (SPS) activities were not significantly changed in T and BE/S in indoor-grown artichokes, while SS activity gradually increased, and SPS activity gradually decreased in field-grown artichokes, alongside sucrose degradation. Compared to T, BE/S generally had higher enzyme activities of 1-FEH and 1-FFT, promoting inulin hydrolysis. This work shows that the process of tuber germination is similar indoors and in the field, and germination studies can therefore be conducted in either environment.