Gut bacterial
community structure and functional analysis in the silkworm Samia ricini reared
on the secondary food plant Tapioca (Manihot esculenta Crantz)
Hatarkhi Mwchahary, Dulur Brahma and Swmdwn Brahma
Res. J. Biotech.; Vol. 21(2); 95-104;
doi: https://doi.org/10.25303/212rjbt0950104; (2026)
Abstract
In the present study, the bacterial diversity in the gut of Eri silkworm (Samia
ricini) fed with tapioca leaves was assessed using a culture-independent metagenomics
approach. Additionally, the study aimed to predict the functional roles of gut bacterial
communities by analysing gene involvement in various KEGG pathways. A total of 564
operational taxonomic units (OTUs) were identified, with Proteobacteria (69.15%),
Firmicutes (28.37%) and Actinobacteria (1.77%) being the dominant phyla. Gammaproteobacteria
was the most abundant class while Enterobacterales emerged as the dominant order,
with Enterobacteriaceae being the most prevalent family. Co-occurrence analysis
revealed nine bacterial genera: Lactobacillus, Enterococcus, Lactococcus, Enterobacter,
Bacillus, Stenotrophomonas, Staphylococcus, Serratia and Klebsiella, suggesting
similar habitat or nutritional niche preferences.
This study represents the report on gut bacterial populations in S. ricini larvae
fed on tapioca leaves, a key secondary food widely adopted by rearers. PICRUSt2
analysis revealed diverse gene functions across KEGG pathways, particularly in membrane
transport, carbohydrate metabolism, amino acid, lipid and nucleotide metabolism,
cellular processing and signalling, gene expression and xenobiotic degradation,
highlighting their roles in host physiology. These findings provide valuable insights
into Eri silkworm gut microbiota, with dominant bacterial taxa having potential
applications in probiotic development and biotechnological metabolite production.
