Strain-specific effect of Streptococcus thermophilus consumption on host physiology

Streptococcus thermophilus is one of the most prevalent species in stool samples of westernized populations due to continuous exposure to fermented dairy products.However,few studies have explored the effect on host physiology by multiple S.thermophilus strains and considered the inter-strain differences in regulating host.In the present study,we investigated how four S.thermophilus strains influenced the gut microbiota,mucin changes,and host metabolism after 28 days of intervention in conventional mice.The results indicated that the consumption of S.thermophilus affected the host with strain specificity.Among four S.thermophilus strains,DYNDL13-4 and DQHXNQ38M61,especially DQHXNQ38M61,had more effect on host physiology by modulating gut microbiota and host metabolism than LMD9 and 4M6.Ingestion of strains DYNDL13-4 and DQHXNQ38M61 resulted in more remarkable changes in amino acid metabolism and lipid metabolism than that of strains LMD9 and 4M6,which may be related to the elevation of intestinal Bifidobacterium by DYNDL13-4 and DQHXNQ38M61.The enriched Coriobacteriaceae UCG-002,Rikenellaceae RC9 gut group,and Lactobacillus only in the DQHXNQ38M61 group,had a close relationship with the prominent effect of DQHXNQ38M61 on regulating amino acid and lipid metabolism.In addition,DQHXNQ38M61 had a strong influence on degrading colonic mucin fucose by decreasedα-fucosidase activity in feces,and improving mucin sulfation by upregulated Gal3ST2 expression.Comparative genomic analysis revealed that the four S.thermophilus strains belonged to different branches in the phylogenetic tree,and DYNDL13-4 and DQHXNQ38M61 had more genes involved in carbohydrate metabolism,amino acid metabolism,membrane transport,and signal transduction,which may confer the capacity of nutrient utilization and gastrointestinal adaptation of the strains and be associated with their strong regulation in host.Our study provides valuable information for understanding the regulation of host metabolism after consuming different S.thermophilus strains and could facilitate potential personalized applications of S.thermophilus based on strain varieties.

Therapeutic effect of Streptococcus thermophilus CRL 1190-fermented milk on chronic gastritis

AIM: To investigate the potential therapeutic effect of exopolysaccharide (EPS)-producing Streptococcus thermophilus (S. thermophilus) CRL 1190 fermented milk on chronic gastritis in Balb/c mice. METHODS: Balb/c mice were fed with the fermented milk for 7 d after inducing gastritis with acetyl-salicylic acid (ASA, 400 mg/kg body weight per day for 10 d). Omeprazole was included in this study as a positive therapeutic control. The gastric in? ammatory activity was evaluated from gastric histology and in? ammation score, number of interleukin-10 (IL-10), interferon-γ (INFγ) and tumor necrosis factor-α (TNF-α) cytokine-producing cells in the gastric mucosa, and thickness of the mucus layer. RESULTS: Animals receiving treatment with the EPS-producing S. thermophilus CRL 1190 fermented milk showed a conserved gastric mucosa structure similar to that of healthy animals. In? ammation scores of the fermented milk-treated mice were lower than those of mice in the gastritis group (0.2 ± 0.03 vs 2.0 ± 0.6, P < 0.05). A marked decrease in INFγ+ (15 ± 1.0 vs 28 ± 1.2, P < 0.05) and TNF-α+ (16 ± 3.0 vs 33 ± 3.0, P < 0.05) cells and an increase in IL-10+ (28 ± 1.5 vs 14 ± 1.3, P < 0.05) cells compared to the gastritis group, was observed. Also, an increase in the thickness of the mucus gel layer (2.2 ± 0.6 vs 1.0 ± 0.3; 5.1 ± 0.8 vs 1.5 ± 0.4 in the corpus and antrum mucosa, respectively, P < 0.05) compared with the gastritis group was noted. A milk suspension of the purif ied EPS from S. thermophilus CRL1190 was also effective as therapy for gastritis.

嗜热链球菌S131对巨噬细胞的免疫调节作用研究

该实验旨在研究嗜热链球菌(Streptococcus thermophilus)S131调节免疫力的功能,并对其提升免疫力的作用机制进行解析。首先,对菌株定殖肠道和产胞外多糖的能力进行评价;然后,通过细胞实验检测菌株对巨噬细胞RAW264.7(小鼠单核巨噬细胞白血病细胞)的增殖、吞噬及对其分泌细胞因子的影响。结果表明,嗜热链球菌S131具有较好的黏附能力,可以高产胞外多糖。其处理RAW264.7细胞后其相对增殖率和吞噬率分别为131.11%和115.13%,且可促细胞分泌肿瘤坏死因子(tumor necrosis factor,TNF-α)、白细胞介素-10(interleukin-10,IL-10)和IL-12细胞因子。综上所述,嗜热链球菌S131可黏附于肠道,可高产胞外多糖,同时可激活巨噬细胞,引起生理性炎症反应,提高机体免疫,能够用于提升免疫力功能食品的开发。

Improving the Health of Teeth in Cats and Dogs with Live Probiotic Bacteria

Background: Periodontal infections are the most common disease of cats and dogs. About 70% - 80% of them suffer from these infections during their lifetime. These infections occur in two forms, gingivitis and periodontitis. Gingivitis is a reversible inflammation of the gingiva which can be cured. As with humans, the harmful bacteria can cause infections also in organs such as the heart, liver and kidneys. Besides veterinary treatment, also the owner’s everyday care is essential. Objective: The aim of the study was to develop and clinically test easy home care probiotic product for cats’ and dogs’ oral health. Methods: Nine cats and thirteen dogs were given a combination of selected bacteria Streptococcus thermophilus SP4, Lactobacillus plantarum 14D and Lactobacillus rhamnosus SP1 (Petguide powder) in powder form daily for four weeks on top of the dry feed. Microbiological samples were taken before and after the intervention from each dog and cat. The samples were analyzed with flow cytometric analysis using Porphyromonas gingivalis and Fusobacterium sp. as indicators for oral health. Results: The home care treatment with these specific, live probiotic bacteria was shown to prevent the growth of infectious bacteria within four weeks. Petguide probiotic powder reduced the relative abundance of infectious microbes significantly (p = 0.005) in cats and dogs. Conclusion: The results suggest that the probiotic product with three live strains of probiotic bacteria prevents the growth of infectious bacterial species that are known to cause infections in pets’ mouths. Therefore, this probiotic combination could be used to improve the oral health of pets and increase their quality of life.

Development of Zn^(2+)-controlled expression system for lactic acid bacteria and its application in engineered probiotics

Lactococcus lactis and Streptococcus thermophilus are considered as ideal chassis of engineered probiotics,while food-grade genetic tools are limited in those strains.Here,a Zn^(2+)-controlled gene expression(ZICE)system was identified in the genome of S.thermophilus CGMCC7.179,including a transcriptional regulator sczAst and a promoter region of cation transporter czcD(PczcDst).Specific binding of the SczAst to the palindromic sequences in PczcDst was demonstrated by EMSA analysis,suggesting the regulation role of SczAst on PczcDst.To evaluate their possibility to control gene expression in vivo,the sczAst-PczcDst was employed to drive the expression of green fluorescence protein(GFP)gene in L.lactis NZ9000 and S.thermophilus CGMCC7.179,respectively.Both of the transformants could express GFP under Zn^(2+)induction,while no fluorescence without Zn^(2+)addition.For optimal conditions,Zn^(2+)was used at a final concentration of 0.8 mM in L.lactis and 0.16 mM in S.thermophilus at OD600 close to 0.4,and omitting yeast extract powder in the medium unexpectedly improved GFP expression level by 2.2-fold.With the help of the ZICE system,engineered L.lactis and S.thermophilus strains were constructed to secret cytokine interleukin-10(IL-10)with immunogenicity,and the IL-10 content in the supernatant of the engineered L.lactis was 59.37%of that under the nisin controlled expression system.This study provided a tightly controlled expression system by the food-grade inducer Zn^(2+),having potential in development of engineered probiotics.