Streptococcus thermophiles DMST-H2 Promotes Recovery in Mice with Antibiotic-Associated Diarrhea.

Antibiotic-associated diarrhea (AAD) is the most common side effect of antibiotics and is routinely treated with probiotics in clinical. Streptococcus thermophiles, extensively utilized for producing dairy foods, has recently been regarded as a new promising probiotic candidate. In this study, the efficacy of Streptococcus thermophiles DMST-H2 (DMST-H2) for AAD treatment in mice was investigated. DMST-H2 was isolated from Chinese traditional yogurt, proved to be non-toxic, and presented tolerance against simulated gastrointestinal conditions in vitro. Additionally, genomic analysis revealed that it possessed genes related to acid tolerance, bile salt tolerance, adhesion, oxidative stress and bacteriocin production. The animal experiment results showed that both DMST-H2 treatment and natural recovery could reduce fecal water content. Compared with spontaneous recovery, DMST-H2 accelerated the recovery of the enlarged caecum and intestinal barrier injury from AAD, and further decreased endotoxin (ET), D-lactate (D-LA) and diamine oxidase (DAO) content in serum. Moreover, pro-inflammatory cytokines (TNF-α) were reduced, while interferon-γ (IFN-γ) and anti-inflammatory cytokines (IL-10) increased after treating with DMST-H2. Furthermore, DMST-H2 better restored the structure of intestinal flora. At the phylum level, Firmicutes increased and Proteobacteria decreased. These findings indicate that DMST-H2 could promote recovery in mice with antibiotic-associated diarrhea.

Biological and Chemical Diversity of Ascidian-Associated Microorganisms.

Ascidians are a class of sessile filter-feeding invertebrates, that provide unique and fertile niches harboring various microorganisms, such as bacteria, actinobacteria, cyanobacteria and fungi. Over 1000 natural products, including alkaloids, cyclic peptides, and polyketides, have been isolated from them, which display diverse properties, such as antibacterial, antifungal, antitumor, and anti-inflammatory activities. Strikingly, direct evidence has confirmed that ~8% of natural products from ascidians are actually produced by symbiotic microorganisms. In this review, we present 150 natural products from microorganisms associated with ascidians that have been reported up to 2017.