Composition and diversity analysis of intestinal microbiota in the fifth instar silkworm, Bombyx mori L.

Abstract

Despite the low diversity and high variability at intra- and interspecific levels, gut microbiota of insect play important roles in digesting and absorbing nutrients, health and development, even in resistance and immunity. In this study, we investigate the composition and diversity of gut microbiota in the 5 th instar of silkworm larvae since the mount of ingested mulberry leaves of this stage is about 85% of the total amount. Intestinal contents were collected at 0, 12, 24, 48 and 72h in the 5 th instar. 32, 21, 29, 24, 14 phyla and 386, 163, 292, 196, 144 genera were detected respectively in the samples described above. In general, the dominated phyla in the larvae gut were Firmicutes, Cyanobacteria, Proteobacteria, Actinobacteria and Bacteroidetes; the dominated genera were Enterococcus, Staphylococcus, Arthrobacter, Pseudomonas, Lactobacillus, Bacteroides, Paenibacillus and Serratia, respectively. The range of phyla and genera was different and there were two peaks of microbial diversity at 0 and 24 h. Compared with the intestinal bacteria of these time points, there were unique bacteria and 56 common ones. In these bacteria, the abundance of Gram-positive bacteria including Enterococcus and Staphylococcus were the highest. Our results provided foundation and reference on the research of intestinal microorganisms and resistance breeding in silkworm.