Isolation And Identification Of Starch Utilization Bacteria In The Gut Of Nile Tilapia And Primary Function Analysis

Fish farming has been received more and more concentration in recent years,because of the nutrition value of fish.Starch that was one kind of the polysaccharide was a crucial component of fish fodder and a facile material.However,teleost tended to utilize protein as energy source instead of starch.High starch proportion in the diet always causes fat deposition and high risk of diseases.Normally,people regulated the ingredients of fodder to enlarge the starch utilization,but this method cannot break the limits of the poor efficiency in starch utilization which caused by the nature of fish.This decade the hotspot studies of intestinal bacteria probably offered an updated method for the problem.Our research started at bacteria screening of starch utilization bacteria from the gut of Nile tilapia.And then one of the screened bacteria(named Sul in this research)was carefully chosen to add in the diet of Nile tilapia.The experiment contained 4 groups including high starch treatment(H group),low starch treatment(L group),high starch treatment with bacteria(HB group)and low starch treatment with bacteria(LB group).After 8 weeks feeding,some indexes of glycometabolism,gut structure and immune were measured.The data indicated the bacteria ameliorated the starch utilization of Nile tilapia and eliminated parts of the negative impacts by the high starch.The blood sugar was decreased in the HB group.Some key enzymes in glycometabolism were stimulated in both LB group and HB group.The inspiring changes possible come from the change in insulin signal pathway.The health condition was enhanced in HB group in the meantime.To analyze the microbiota composition and functions,high-throughput sequencing was carried out and the results illustrated that Verrucomicrobia was highly increased in high starch with bacteria group.The phylum was thought as the candidate for polysaccharide-degrading.The bacteria Sul possible alter the microbiota composition to impact on the host.This study was one of the earliest works to explore the relationship between host and microbe in aquaculture.We provided a new way to solve the starch utilization problem.After expounding the role of intestinal microbe,there may have a hope to apply the method for improving nutrition metabolism in the host.