Effects Of Sugars As Carbon Sources On Intestinal Microfl Ora Of Litopenaeus Vannamei

The experiment was divided into two parts:the effects of four sugars on the growt h,metabolism,immunity and intestinal flora of Litopenaeus vannamei,and the effe cts of three sugars as carbon sources on Bacillus and bifidobacteria at two tempera tures.The effects of different carbohydrate as carbon sources on growth and metab olism,immunity and intestinal flora of Litopenaeus vannamei,as well as the prolif eration of common probiotics in the intestine,can provide a theoretical basis for th e future cultivation and the addition of microbial agents in feed,reduce the feed c ost and improve the aquaculture yield.Experiment one:The aim of this experiment was to study the effects of four comm on sugar sources on the growth,digestive enzymes and intestinal flora of L.vanna mei.Four kinds of common sugars(glucose,fructose,starch and sucrose)were sele cted as sugar sources to prepare feed for L.vannamei with initial body weight of(0.36±0.02)g.there were 4 treatments in total,3 replicates in each treatment,40 L.vannamei in each replicate.The culture cycle was 56 days,and the addition amo unt of each sugar source was 20%.Research shows:(1)The specific growth rate a nd protein efficiency of L.vannamei were significantly different(P<0.05),and the starch group was significantly higher than the other three groups(P<0.05),but ther e were no significant differences in feed coefficient,survival rate,liver body ratio and meat content rate among the groups(P>0.05).The crude fat in sucrose group was significantly lower than that in other three groups(P<0.05),ash content in glu cose group was significantly higher than that in other three groups(P<0.05),there was no significant difference in crude protein and water content among groups(P>0.05),and there was no significant difference in muscle nutrients among groups(P>0.05).(2)The levels of hexokinase(HK)and malate dehydrogenase(MDH)in sucrose group were significantly higher than those in other three groups(P<0.05),while glutamine synthetase(GS)and glutamic oxaloacetic transaminase(got)starch group were significantly higher than those of the other three groups(P<0.05).Ther e was no significant difference in the fructose group,starch group and sucrose gro up of phosphofructokinase(PFK),but they were significantly higher than that of gl ucose group.(3)The triglyceride of glucose group was significantly higher than th at of the other three groups(P<0.05),and the blood glucose of fructose group was significantly higher than that of the other three groups(P<0.05),but the total cho lesterol had no significant difference(P>0.05).(4)The activities of superoxide dis mutase(SOD),nitric oxide synthase(NOS)and alkaline phosphatase(AKP)in star ch group were significantly higher than those in other three groups(P<0.05),while acid phosphatase(ACP)activity in sucrose group was significantly higher than tha t in other three groups(P<0.05).(5)There was significant difference in digestive enzyme activity between the three groups(P<0.05),The activity of lipase(LPS)in starch group and sucrose group was significantly higher than that in glucose grou p and fructose group(P<0.05),but there was no significant difference between star ch group and sucrose group(P>0.05),while pepsin(PPS)activity in starch group was significantly higher than that in other three groups(P<0.05).(6)There are 18 microbial species in the intestinal samples of L.vannamei,which are classified into 37 classes,75 orders,125 families and 195 genera.There was no significant diffe rence in OTU,ACE and Chao index in the intestine of L.vannamei(P>0.05),In th e basic composition of microbial community,the sucrose group was more than that of starch group,Shannon index starch group and sucrose group were significantly higher than glucose group,while Simpson index starch group was significantly to wer than sucrose group,and sucrose group was significantly lower than glucose gr oup(P<0.05).(7)At the phylum level,the relative abundance of Proteobacteria in sucrose group was significantly higher than that in glucose group,and the relative abundance of Bacteroidetes and Actinobacteria in starch group was significantly hig her than that in glucose group,but there was no significant difference in relative a bundance of verrucomicrobia among the groups;at the class level,the intestinal mi croflora of prawn in each treatment group was significantly higher than that in glu cose group Flavobacterium,gamma Proteobacteria,Actinobacteria and Cytophagia w ere significantly higher in starch group than in sucrose group and glucose group,A t the order level and family level,the number of Flavobacterium in starch group was significantly higher than that in the other two groups,and the proportion of F lavobacterium and Rhodobacter ace was relatively large.At the genus level,the pr oportion of unclassified Flavobacterium in starch group and sucrose group was high er than that in glucose group,but there was no significant difference between the t wo groups,but the proportion of Flavobacterium in starch group was still higher t han that in glucose group and sucrose group,and the proportion of bacteria in eac h group was significantly different.In conclusion,the absorption and utilization of s tarch and sucrose in L.vannamei were better than glucose and fructose.At the sa me time,starch and sucrose had certain effects on the intestinal flora diversity of L.vannamei.Starch and sucrose were the suitable sugar sources in the feed of L.vannamei.Experiment two:This experiment was conducted to study the effects of three sugars as carbon sources on Bacillus subtilis(8411)and Bifidobacterium(ATCC 29521)un der two temperature conditions,and whether the metabolites of Bacillus subtilis co uld promote the growth of Bifidobacterium bifidum.The probiotics Bacillus subtilis and Bifidobacterium bifidum were selected as experimental strains.Three kinds of 1 iquid culture media were prepared with 28℃,35℃/37℃ glucose,starch and sucrose as carbon sources.There were 6 treatments in total and 3 replicates in each treat ment.The experiment is divided into two parts:Firstly,Bacillus subtilis was inocula ted into three kinds of media for constant temperature cultivation at 28℃ and 35℃,and Bifidobacterium bifidum was inoculated into three kinds of culture media at 28℃ and 37℃.OD values of bacterial liquid were measured at 24h,48h and 72h respectively.Secondly,Bifidobacterium bifidum was inoculated into Bacillus subt ilis solution cultured at 28℃ and 35℃ for 72h.Paraffin oil was isolated from oxy gen and cultured at 28℃ and 37℃ at constant temperature.OD values of bacterial liquid were determined at 24h,48h and 72h,respectively.The test results show th at:(1)The OD value of starch group and sucrose group was significantly higher tha n that of glucose group,and the OD value of starch group was significantly highe r than that of sucrose group at 24h(P<0.05).However,there was no significant di fference among the groups at 28℃(P>0.05).The temperature had significant effect on the proliferation of Bacillus in vitro,35℃>28℃(P<0.05).(2)The effect of su gar source on the proliferation of Bifidobacterium in vitro was significant(P<0.05).At 37℃,starch group was significantly higher than sucrose group,sucrose group was significantly higher than glucose group(P<0.05).At 28℃,OD value of starch group and sucrose group was significantly higher than that of glucose group(P<0.05).Temperature had a significant effect on the proliferation of Bifidobacterium in vitro,28℃>37℃(P<0.05).The interaction between glucose source and temperature was significant at 24h and 72h(P<0.05),but not at 48h(P>0.05).(3)At 28℃ for 24h,the OD value of sucrose group was significantly higher than that of glucose group and starch group(P<0.05).At 48h,starch group and sucrose group were si gnificantly higher than glucose group(P<0.05),but there was no significant differe nce between groups at 72h(P>0.05).At 37℃,the OD value of starch group was significantly higher than that of sucrose group,sucrose group was significantly high er than that of glucose group(P<0.05),and that of starch group and sucrose group was significantly higher than that of glucose group at 72h(P<0.05).In conclusion,different sugars as carbon sources at different temperatures have certain effects on the proliferation of Bacillus and Bifidobacteria in vitro.Starch and sucrose are th e favorable carbon sources for the growth of Bacillus and Bifidobacteria.