| Fresh mulberry leaf is the best natural feed of Bombyx mori larvae.However,for almost all silkworm varieties bred so far,only the intake of artificial diets by larvae has been improved,while the metabolic utilization of artificial diets is still not as good as that of mulberry leaves.Issues such as weak silkworm larvae,low silk protein synthesis efficiency,and low silk yields in silkworms reared on artificial diets have not been resolved.In order to further explore the remaining problems of artificial diets,in this paper,the metabonomics and microbiome methods were used to analyze the relationship between feeding habits and dietary of gut microbiota and hemolymph metabolic differences.The results are as follows:(1)The metabolomics is based on the disruptive selected the ingestive behavior of Jingsong B silkworm varieties obtained to artificial diet feeding habit differences silkworm strains,compared with reared on fresh mulberry leaves and the artificial diet,Jingsong B high food intake strains.Comparison of Jingsong B high food intake strains and Jingsong B low food intake reared on fresh mulberry leaves when the fifth instar larvae hemolymph metabonomics differences.GC / LC-MS analysis showed that,we unambiguously assigned 130 metabolites,amino acid,organic acid and vitamin are the most different metabolites.The contents of four types of vitamins including thiamine in the haemolymph of silkworms reared on artificial diet were significantly decreased compared with those reared on mulberry leaves,and they constituted a large number of edges with 59 differential metabolites.The contents of 15 kinds of amino acids and their metabolites including methionine sulfoxide were significantly increased,while the contents of six kinds of essential and non-essential amino acids including methionine and lysine were significantly decreased.The contents of glycine,alanine,asparagine and serine,the most dominant amino acids in silk protein,were significantly either downregulated or upregulated.Meanwhile,the contents of key substances in the metabolic pathways of uric acid and urea formation from amino acids were significantly increased,and uric acid and urea were enriched in the haemolymph.On the other hand,the contents of organic acids such as pipecolic acid and quinic acid were significantly decreased,the levels of carbohydrate metabolism,lipid metabolism,and cholesterol were lower than those in silkworms reared on mulberry leaves.In this paper,10 male dominant metabolites and 29 feed-related differential metabolites between sexes were also screened out,which will provide clues and targets for further study on the mechanism of difference in adaptability to artificial diet between silkworm sexes.(2)In order to understand the impact of silkworm varieties,we used two high similar genetic source of Jingsong B high food intake strain(Hi)and Jingsong B low food intake strain(Lo),one natural mutation of artificial diets feeding well Guangshi strain(Gs),and another natural strain of Lu 7(L7)in which almost all its larvae starved to death on the artificial diets.Results of their gut microbiomics shown as follows:In the mulberry leaves breeding larvae,the diversity of intestinal microbes was similar in the four silkworm strains,even if there are significant differences in the feed intake to artificial diets.The most abundant microorganism was Cyanobacteria which up to 65.2 ± 17.9% of total gut microorganisms,followed by the Firmicutes(29.2 ± 17.6%),the third and the fourth intestinal bacteria was Proteobacteria(4.2 ± 4.5%)and Bacteroidetes(0.6 ± 0.8%),respectively.On the genus level,the most predominant bacteria of Streptophyta(o)was up to 65.2 ± 17.9% of total gut microorganisms,followed was Enterococcus(19.4 ± 12.7%)and Clostridium(7.6 ± 12.7%),which was involved in host immunity and hydrolyzing sugar and protein.The diversity of gut microbiota was significantly decreased in silkworm guts reared on artificial diets,and the abundance of dominant bacteria were significantly changed.Compare with silkworms reared on fresh mulberry leaves,the abundance of Cyanobacteria was decreased 67.9 ± 20.7% and 99.1 ± 0.6% in artificial diets reared Hi and Gs,respectively.The Firmicutes was up-regulated 5.5 ± 1.6 times in Hi and decreased 41.7 ± 30.7% in Gs.The abundance of Proteobacteria was up-regulated 32.9 ± 8.1 times in the larval intestine of Gs,while there was no significant change in Hi strain.Further in-depth classification analysis showed that nearly 99% of the intestine bacteria reared on artificial diet were not classified into the genus.In gut of Hi reared on artificial diets,the abundance of Enterococcaceae was up-regulated 10.1 ± 2.8 times,while the Streptophyta(o)decreased 67.8 ± 20.7%.Whereas,the Enterobacteriaceae was up-regulated 64.0 ± 15.4 times,but the Streptophyta(o)and Lachnospiraceae was decreased 99.1 ± 0.6% and 99.99% ± 0.01% in Gs,respectively.The results of PICRUSt in the KEGG database showed that the gut microbiota of silkworms reared on fresh mulberry leaves was mainly affected by Excretory System and Xenobiotics Biodegradation and Metabolism.In addition,compared with silkworms reared on fresh mulberry leaves,the diversity of gut microbiota involved in host environmental adaptation,Cell Growth and Death,Cell Motility,genetic information processing and so on were significantly increased.In general,the composition of gut microbiota and diets have a strong relationship.The gut microbiota in silkworm larvae reared on fresh mulberry leaves maintained in a relatively stable state,most no effect from genetic differences on artificial diet feeding habits(silkworm strains).The gut microbial diversity and the functional for the host might been great changed in silkworm reared on artificial diets.The results showing that diet is the main factor to change the gut microbiota of silkworm,the changes of intestinal microflora under the larvae reared on artificial diets was related to the genetic differences of the host silkworm. |
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