Effect Of Clostridium Butyricum On Intestinal Microbiota And Resistance To Vibrio Alginolyticus Of Penaeus Vannamei

Penaeus Vannamei(P.vannamei)is an economically important shrimp species in the world,and with the rapid development of intensive farming,bacterial diseases have seriously hampered the shrimp culture industry,with infections caused by Vibrio lysozyme causing serious economic losses.Antibiotics can effectively treat bacterial infections in shrimp culture,but they are also prone to cause other problems.Probiotics are widely used in aquaculture as one of the alternatives to antibiotics.Clostridium butyricum is widely used in animal breeding as a probiotics,but the clinical data of Clostridium butyricum is still unclear in the process of Penaeus vannamei culture.In order to study the effect of adding Clostridium butyrate in feed on intestinal microorganisms and anti-vibrio infection of Penaeus vannamei,we designed experiments to carry out research,and the specific results are as follows:We set up two groups:fed normal shrimp feed(CG30)and fed feed supplemented with1x10~7CFU/mg of Vibrio butyricum(CB30)for a 30-day Vibrio butyricum feeding trial and analyzed the alteration of intestinal microorganisms by 16s macrogenome.Subsequently,to evaluate the protection of Clostridium butyricum consumption against Vibrio alginolyticus infection in P.vannamei,four groups were set up:CG30 group injected with sterile PBS(CG),CB30 group injected with sterile PBS(CB),CG30 group injected with Vibrio alginolyticus(VACG)and CB30 group injected with Vibrio alginolyticus(VACB)for a 24 h acute infection test.We explained the protective effect of Clostridium butyricum against Vibrio algicans infection in terms of survival,histopathology,changes in enzyme activity,transcriptome analysis and immune-related genes.We found that feeding Clostridium butyricum did not significantly affect intestinal microbial diversity,but significantly altered the structural portions of microbial populations,such as significantly reducing the abundance of Vibrionaceae and Vibrio in the intestinal microbiota(P?0.05).In the Vibrio alginolyticus infection test,Clostridium butyricum significantly increased the survival rate of P.vannamei(P?0.05).Clostridium butyricum reduced the pathological changes in hepatopancreas tissue caused by Vibrio lysis infection,alleviated the infection-induced decrease in superoxide dismutase(SOD)and phenol oxidase(PO)activities,and increased the lysozyme content in the hepatopancreas of white shrimp.Compared with VACG group,the VACB group screened 1730 significantly up-regulated genes(differentially expressed genes)and 2029 significantly down-regulated genes(P?0.05).Among them,the up-regulated genes were significantly enriched in peptidase inhibitor activity(peptidase inhibitor activity),enzyme regulator activity(enzyme regulator activity),enzyme inhibitor activity(enzyme inhibitor activity,molecular function regulator,extracellular region,endopeptidase inhibitor activity,endopeptidase regulator endopeptidase inhibitor activity,endopeptidase regulator activity,cell junction,cell-cell junction,gap junction,pyridoxal phosphate binding,vitamin B6 binding,and signaling receptor binding,with significant enrichment of down-regulated genes in transmembrane transport,iron ion binding,lipid lipid transporter activity,lipid transport,oxidoreductase activity,lipid localization,and oxidoreductase activity-paired donor.oxidoreductase activity-paired donors,heme binding,hydrolase activity,tetrapyrrole binding,hydrolase activity-glycosyl bonds,heme binding activity-glycosyl bonds,oxidation-reduction process,transporter activity,carbohydrate metabolic process,sulfate hydrolase activity,phosphatidyl inositol binding,fatty acid metabolic process,and lipid biosynthesis process.biosynthetic process).Quantitative real-time PCR(q RT-PCR)showed that Vibrio alginolyticus caused overexpression of alkaline phosphatase(AKP)transcription factors,however,supplementation of diets with Clostridium butyricum significantly suppressed AKP upregulation caused by infection.Vibrio lysozyme infection caused a decrease in the expression of propanol oxidase(PO),α-2-macroglobulin(A2M)and anti-lipid glycosyl factor(ALF)transcription factors in the hepatopancreas of white shrimp,but this decrease was suppressed to some extent by the consumption of Clostridium butyricum.In conclusion,the addition of Clostridium butyricum to the feed altered the abundance ratio of microbial populations in the gut of S.cerevisiae.However,shrimp fed with Clostridium butyricum and shrimp fed with normal feed had higher survival rate and lower hepatopancreatic tissue damage under the same Vibrio lysis infection,which suppressed the reduction of oxidase activity and immune-related gene expression caused by the infection.Clostridium butyricum has the potential to act as an inhibitor of Vibrio lysozyme infection and help improve the resistance of P.vannamei to Vibrio lysozyme infection.