Butyrate-producing bacteria (BPB) benefit the health of aquatic animals. This current study aimed to isolate BPB from the intestines of Nibea coibor and assess their probiotic potential. The results showed that nine isolates were obtained in vitro from the gut of N. coibor, including six Clostridium butyricum, two Proteocatella sphenisci, and one Fusobacterium varium. The representative bacteria, C. butyricum CG-3 and P. sphenisci DG-1, which produce high butyrate levels, were further studied for short-chain fatty acid (SCFA) production and antibiotic susceptibility. The effects of BPB singly (CB: basal diet + CG-3 and PS: basal diet + DG-1, at 107 CFU/g) or in combination with galactooligosaccharides (GOS) (0.5%) and inulin (0.5%) (CBIG) or D-sorbitol (0.5%) (PSGS) on the growth and health status of N. coibor were investigated. Results showed an increase in growth parameters in the CB, CBIG, and PSGS groups, except for the PS group. Alterations in intestinal microbiota (including diversity, abundance, and function) were observed in four experimental groups (CB, CBIG, PS, and PSGS groups). SCFA contents increased in treated groups; butyrate production was positively related to bacterial abundance. Compared to control, levels of complement C3, complement C4, immunoglobulin M (IgM), transforming growth factor-β (TGF-β), interleukin (IL)-10, IL-1β, and lysozyme (LZM) increased, while malondialdehyde (MDA) decreased in treated groups. Contents of IL-6 (PS and PSGS groups), tumor necrosis factor-alpha (TNF-α) (CB, PS, and PSGS groups), total antioxidant capacity (T-AOC) (CB and PS groups), total superoxide dismutase (T-SOD) (PS group), catalase (CAT) (CB and PSGS groups), and activities of amylase (PS and PSGS groups), trypsin (CB group), and lipase (CBIG group) were increased. Our results suggested the potential use of C. butyricum CG-1 or P. sphenisci DG-1 singly or in combination with prebiotics improved growth and health conditions in N. coibor.
Abstract Clostridium butyricum is a bacterium of rod shape, strictly anaerobic, Gram‐positive and form spores. Short‐chain fatty acids, biofuel compounds and precursors of biomaterials (H 2 , butanol and 1,3‐propanediol) are produced by C. butyricum during the fermentation of carbohydrates and sugars. In humans and animals, although C. butyricum has been found to be associated with botulism in infant and necrotising enterocolitis in preterm neonates, some strains have been demonstrated to be beneficial as probiotics. In aquatic animals, the application of C. butyricum as a probiotic has been commonly considered. In this review, we described and documented what we knew about the isolation, identification, phenotypic and biochemical characteristics, safety, pathogenicity and the mechanisms of action of C. butyricum in the gastrointestinal tract of aquatic animals. The evidence on the roles that C. butyricum plays in improving growth performance, digestibility, survival rate, immune response, disease resistance and the structure of intestinal tract, as well as the modulation of gut commensal microbiota and metabolic disorders in aquatic animals, is summarised. Albeit the probiotic C. butyricum has been applied in aquaculture, and further research, such as the inter‐relationships between the probiotic and the immune system of the host and the possible application of C. butyricum as an alternative to antibiotic substitution for the prevention and treatment of diseases, is required for future detailed studies.
Reactive oxygen species (ROS), a group of unstable and highly reactive molecules or free radicals, are productions of molecular oxygen through cell metabolism. In invertebrates, especially in crustaceans, hemolymph plays an extremely important role in innate immune regulation and inflammatory responses, in which various microbes were modified by ROS. Even so, the information about ROS in relation to hemolymph microbiota and innate immunity is still limited in mud crab. To investigate the underlying mechanism, the ROS-excessive mud crabs (Scylla paramamosain) caused by knocking down catalase (SpCAT) were used to demonstrate the effects of abnormal levels of ROS on the changes in the hemolymph microbiota. Our results showed that SpCAT silence significantly increase ROS production and decrease the load of the bacteria in the hemolymph in mud crab. In the siCAT group, the dominant phyla were Proteobacteria, Actinobacteria, Acidonacteria, Bacteroidetes, Firmicutes, Gemmatimonadetes, Chloroflexi, Planctomycetes, Rokubacteria and Verrucommicrobia. Among them, the relative abundance of Firmicutes and Cyanobacteria was significantly increased upon the elevated ROS production. Some bacterial genera such as Bacteroides, Parabacteroides, Faecalibacterium and Romboutsia also increased with higher level of ROS. Moreover, the results showed that excessive ROS could promote the evident autophagy of the hemocytes. The result of this study demonstrated that ROS plays a vital role in modulating the homeostasis of the microbiota, and SpCAT is also crucially important in the ROS-mediated hemolymph microbiota homeostasis and the autophagy of the hemocytes in mud crab.
Abstract Background Systemic lupus erythematosus (SLE) is a complex systemic autoimmune disease characterized by the presence of numerous autoantibodies. The interaction of infectious agents (viruses, bacteria and parasites) and a genetically susceptible host may be a key mechanism for SLE. Toxoplasma gondii is a widespread intracellular parasite that has been implicated in the pathogenesis of autoimmune diseases. However, the relationship between T. gondii infection and the increased risk of SLE in Chinese populations remains unclear. Methods The seroprevalence of T. gondii infection was assessed in 1771 serum samples collected from Chinese individuals (908 healthy controls and 863 SLE patients) from different regions of China using an enzyme-linked immunosorbent assay. Serum autoantibodies and clinical information were obtained and analysed. Results Our observations revealed a higher prevalence of anti- T. gondii antibodies (ATxA) immunoglobulin G (IgG) in serum samples from SLE patients (144/863, 16.7%) than in those from the healthy controls (53/917, 5.8%; P < 0.0001), indicating a 2.48-fold increased risk of SLE in the ATxA-IgG + population, after adjustment for age and sex (95% confidence interval [CI] 1.70–3.62, P < 0.0001). ATxA-IgG + SLE patients also showed a 1.75-fold higher risk of developing moderate and severe lupus symptoms (95% CI 1.14–2.70, P = 0.011) compared to ATxA-IgG − patients. Relative to ATxA-IgG − patients, ATxA-IgG + patients were more likely to develop specific clinical symptoms, including discoid rash, oral ulcer, myalgia and alopecia. Seven antibodies, namely anti-ribosomal RNA protein (rRNP), anti-double stranded DNA (dsDNA), anti-cell membrane DNA (cmDNA), anti-scleroderma-70 (Scl-70), anti-cardiolipin (CL), anti-beta2-glycoprotein-I (B2GPI) and rheumatoid factor (RF), occurred more frequently in ATxA-IgG + patients. When combined with anti-dsDNA and RF/anti-rRNP/anti-cmDNA/ESR, ATxA-IgG significantly increased the risk for severe lupus. Conclusions Our results suggest that ATxA-IgG may be a significant risk factor for SLE prevalence and severity in Chinese populations. Graphical Abstract
Dietary carbohydrates are anaerobically fermented by gut microbiota to short-chain fatty acids (SCFAs), conferring gut health benefits. Of all tested prebiotics, galactooligosaccharides (GOS) and resistant starch (RS) stimulated the SCFA production in mud crab (Scylla paramamosain), a crustacean model, to a greater extent than the other carbohydrates tested. Using in vitro anaerobic fermentation cultures, this study further explored the prebiotic potential of GOS and RS in mud crab by assessing their impacts on gut microbiota changes and SCFA production. Both GOS and RS significantly promoted SCFA production. Bacterial diversity in the GOS group was lower than in the RS or control group. GOS promoted the growth of Bacteroidetes, while RS promoted Tenericutes. A strong positive correlation was found between SCFA production and bacterial abundance; most bacteria per se correlated with each other. The findings demonstrated the prebiotic potential of GOS and RS in mud crab.
Abstract Gut microbiota is important and plays a crucial role in the host health and nutritional metabolism through multiple mechanisms. Short‐chain fatty acids (SCFAs), which are carboxylic acids with aliphatic tails < 6 carbons, are mainly produced by anaerobic microbiota through fermentation of carbohydrates in the intestine. Acetate, propionate and butyrate are the most abundant SCFAs metabolites, important in energy homoeostasis, metabolism and the maintenance of gut health. In this review, we describe and document what is known about the production, absorption, transport and receptors as well as the factors that affect SCFA production in aquatic animals. Some evidence on the roles that SCFAs as feed additives play in improving growth performance, digestibility, survival rate, immune responses, disease resistance and structure and function of the intestinal tract and abundance of commensal microbiota in aquatic animals is summarized. In addition, the immune regulatory mechanism of SCFAs is highlighted. Although the effects of SCFAs in aquatic animals have been explored, further research is needed to profoundly investigate the mechanisms that by which SCFAs induce their effects on host metabolism.
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