Probiotics are microbial strains that are beneficial to health, and their potential has recently led to a significant increase in research interest in their use to modulate the gut microbiota. The animal gut is a complex ecosystem of host cells, microbiota, and available nutrients, and the microbiota prevents several degenerative diseases in humans and animals via immunomodulation. The gut microbiota and its influence on human nutrition, metabolism, physiology, and immunity are addressed, and several probiotic species and strains are discussed to improve the understanding of modulation of gut microbiota. This paper provides a broad review of several Lactobacillus spp., Bifidobacterium spp., and other coliform bacteria as the most promising probiotic species and their role in the prevention of degenerative diseases, such as obesity, diabetes, cancer, cardiovascular diseases, malignancy, liver disease, and inflammatory bowel disease. This review also discusses a recent study of Saccharomyces spp. in which inflammation was prevented by promotion of proinflammatory immune function via the production of short-chain fatty acids. A summary of gut microbiota alteration with future perspectives is also provided.

The objective of this experiment was to investigate oxidative injury and the development of an antioxidant system after early weaning in piglets. A total of 40 piglets (Landrace× Large White, weaned at 14 d after birth) were randomly slaughtered 0 (w0d), 1 (w1d), 3 (w3d), 5 (w5d), or 7 d (w7d; n = 8) after weaning. Concentrations of malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), and protein carbonyl and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase were measured in plasma. Gene expressions of antioxidant enzymes were determined by quantitative reverse transcription PCR analysis. The mediation of transcription factor 65 (p65) and the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways by oxidative stress was determined by Western blot analysis. Results showed that the plasma MDA level was significantly higher at 3 d (P < 0.05) and that the protein carbonyl level increased at 1, 3, and 5 d (P < 0.05) compared with w0d. In addition, early weaning suppressed the plasma activity of SOD at 1 d (P < 0.05) and reduced the GSH-Px activity at 3 d (P < 0.05). The expression results in the jejunum indicate that the genes related to antioxidant enzymes were downregulated (P < 0.05) at 3 and 5 d after weaning. Uncoupling protein 2 (Ucp2), which is considered to be a feedback regulation on reactive oxygen species generation, tended to decrease in the ileum (P < 0.05) after weaning. Tumor protein 53 (p53), which regulates reactive oxygen species generation, was enhanced (P < 0.05) in the jejunum after weaning. Meanwhile, early weaning suppressed p65 (at 3, 5, and 7 d; P < 0.05) and Nrf2 (at 5 and 7 d; P < 0.05) signals in the jejunum, which might feedback-regulate antioxidant gene expression and promote the development of the antioxidant system. Therefore, we speculate that weaning disrupted oxidative balance and caused oxidative injury in piglets, and this imbalance can recover with the development of an antioxidant system via feedback regulation.

Feelings of hunger and satiety are the key determinants for maintaining the life of humans and animals. Disturbed appetite control may disrupt the metabolic health of the host and cause various metabolic disorders. A variety of factors have been implicated in appetite control, including gut microbiota, which develop the intricate interactions to manipulate the metabolic requirements and hedonic feelings. Gut microbial metabolites and components act as appetite-related signaling molecules to regulate appetite-related hormone secretion and the immune system, or act directly on hypothalamic neurons. Herein, we summarize the effects of gut microbiota on host appetite and consider the potential molecular mechanisms. Furthermore, we propose that the manipulation of gut microbiota represents a clinical therapeutic potential for lessening the development and consequence of appetite-related disorders.

Diarrhea is a common problem to the whole world and the occurrence of diarrhea is highly associated with gut microbiota, such as bacteria, fungi, and viruses. Generally, diarrheal patients or animals are characterized by gut microbiota dysbiosis and pathogen infections may lead to diarrheal phenotypes. Of relevance, reprograming gut microbiota communities by dietary probiotics or fecal bacteria transplantation are widely introduced to treat or prevent diarrhea. In this review, we discussed the influence of the gut microbiota in the infection of diarrhea pathogens, and updated the research of reshaping the gut microbiota to prevent or treat diarrhea for the past few years. Together, gut microbiota manipulation is of great significance to the prevention and treatment of diarrhea, and further insight into the function of the gut microbiota will help to discover more anti-diarrhea probiotics.