ABSTRACT. The ratio of Bacteroidetes and Firmicutes bacterial groups in the gut can affect the ability to absorb nutrients. We investigated the effect of probiotic Bacillus subtilis supplementation of diets on growth performance, fat deposition, blood lipids, copy numbers, and percentage of Bacteroidetes and Firmicutes in cecal contents, as well as mRNA expression of key lipid metabolism enzymes in the liver and adipose tissue of finishing pigs. Twenty-four Duroc x Meishan crossbreed 8-week-old pigs (10.28 ± 0.59 kg) were randomly allocated to two dietary treatments: maize-soybean mealbased diets with B. subtilis (probiotic group) and without B. subtilis (control group). The probiotic diet led to a significant increase in the average daily gain and feed conversion ratio of pigs weighing 10 to 110 kg. The mean backfat depth was increased while leaf lard weights were decreased by probiotic supplementation. Ingestion of probiotics decreased the serum triglyceride and glucose concentrations, but did not change the levels of total cholesterol and free fatty acids in the serum. The mRNA expressions of fatty acid synthase (FAS) and acetylCoA carboxylase α (ACCα) in the liver were down-regulated by the dietary probiotic supplement. Conversely, the gene expressions of FAS and ACCα in the adipose tissue increased. The probiotic diet decreased the copy numbers and percentage of Bacteroidetes, while it increased the percentage of Firmicutes in the cecal contents. We conclude that the addition of B. subtilis improves growth performance and up-regulates lipid metabolism in subcutaneous fat of finishing pigs. We conclude that B. subtilis affects lipid metabolism through regulation of the proportion of Bacteroidetes and Firmicutes in the gut.

Previous studies have suggested that immune system development and weaning stress are closely related to the maturation of gut microbiota. The early-life period is a "window of opportunity" for microbial colonization, which potentially has a critical impact on the development of the immune system. Fecal microbiota transplantation (FMT) and probiotics are often used to regulate gut microbial colonization. This study aims to test whether early intervention with FMT using fecal microbiota from gestation sows combined with Clostridium butyricum and Saccharomyces boulardii (FMT-CS) administration could promote the maturation of gut microbiota and development of immune system in piglets. Piglets were assigned to control (n = 84) and FMT-CS treatment (n = 106), which were treated with placebo and bacterial suspension during the first three days after birth, respectively. By 16S rRNA gene sequencing, we found that FMT-CS increased the α-diversity and reduced the unweighted UniFrac distances of the OTU community. Besides, FMT-CS increased the relative abundance of beneficial bacteria, while decreasing that of opportunistic pathogens. FMT-CS also enhanced the relative abundance of genes related to cofactors and vitamin, energy, and amino acid metabolisms during the early-life period. ELISA analysis revealed that FMT-CS gave rise to the plasma concentrations of IL-23, IL-17, and IL-22, as well as the plasma levels of anti-M.hyo and anti-PCV2 antibodies. Furthermore, the FMT-CS-treated piglets showed decreases in inflammation levels and oxidative stress injury, and improvement of intestinal barrier function after weaning as well. Taken together, our results suggest that early-life intervention with FMT-CS could promote the development of innate and adaptive immune system and vaccine efficacy, and subsequently alleviate weaning stress through promoting the maturation of gut microbiota in piglets.

Bacterial vaginosis (BV) is the most common vaginal infection found inwomen in the world. Due to increasing drug-resistance of virulent pathogen such as Gardnerella vaginalis (G. vaginalis), more than half of BV patients suffer recurrence after antibotics treatment. Here, metastable iron sulfides (mFeS) act in a Gram-dependent manner to kill bacteria, with the ability to counteract resistant G. vaginalis for BV treatment. With screening of iron sulfide minerals, metastable Fe 3 S 4 shows suppressive effect on bacterial growth with an order: Gram-variable G. vaginalis >Gram-negative bacteria>> Gram-positive bacteria. Further studies on mechanism of action (MoA) discover that the polysulfide species released from Fe 3 S 4 selectively permeate bacteria with thin wall and subsequently interrupt energy metabolism by inhibiting glucokinase in glycolysis, and is further synergized by simultaneously released ferrous iron that induces bactericidal damage. Such multiple MoAs enable Fe 3 S 4 to counteract G. vaginalis strains with metronidazole-resistance and persisters in biofilm or intracellular vacuole, without developing new drug resistance and killing probiotic bacteria. The Fe 3 S 4 regimens successfully ameliorate BV with resistant G. vaginalis in mouse models and eliminate pathogens from patients suffering BV. Collectively, mFeS represent an antibacterial alternative with distinct MoA able to treat challenged BV and improve women health.

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is a chronic inflammatory disease affecting the colon, and its incidence is rising worldwide.

Dietary fiber, an important regulator of intestinal microbiota, is a promising tool for preventing obesity and related metabolic disorders. However, the functional links between dietary fiber, intestinal microbiota, and obesity phenotype are still not fully understood. Combined soluble fiber (CSF) is a synthetic mixture of polysaccharides and displays high viscosity, water-binding capacity, swelling capacity, and fermentability. We found that supplementing high-fat diet (HFD) with 6% CSF significantly improved the insulin sensitivity of obese mice without affecting their body weight. Replacing the HFD with normal chow basal diet (NCD), the presence of CSF in the feed significantly enhanced satiety, decreased energy intake, promoted weight and fat loss, and augmented insulin sensitivity. CSF also improved the intestinal morphological integrity, attenuated systemic inflammation, promoted intestinal microbiota homeostasis, and stabilized the production of short-chain fatty acids (SCFAs) that was perturbed during HFD-induced obesity, and these stabilizing effects were more prominent when the basal diet was switched to NCD. The enrichment of bacteria of the S24-7 family and Allobaculum genus increased markedly in the intestine following 6% CSF supplementation- and correlated with decreased adiposity and insulin resistance. Five bacterial genera that were decreased by CSF, including Oscillospira, unclassified Lachonospitaceae, unclassified Clostridiales, unclassified Desulfovibrionaceae, and unclassified Ruminococcae, were subjected to co-occurrence network analysis and were positively correlated to adiposity and insulin resistance, indicating a key role in the microbial response to CSF. Thus, CSF has a potential to promote insulin sensitivity and even reduce obesity via beneficial regulation of the gut microecosystem.