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solutions for pest control [5]. Several insect orders including Coleoptera [6], Hemiptera [7], Hymenoptera [8] and Diptera [9, 10] have been reported to harbor persistent communities of microorganisms. However, the gut microbiome of Lepidoptera is sparsely described [11]. Out of the 157,424 recognized Lepidoptera species [12], <0.1% have been screened for bacterial symbionts, revealing the limited available knowledge on bacterial associates in Lepidoptera [13]. The lepidopteran microbiome is driven by many factors ranging from the environment, diet, gut physiology, and developmental stage [13]. Studies on insect gut bacteria have utilized both cultivable and culture-independent approaches [14]. Cultivable microbes are ideal for studying symbiotic interactions sustained within the host and are also ready to be genetically manipulated for other novel applications [15]. Conventional cultivation techniques are, however, unable to characterize most microbes with 80-90% of microbial species not yet cultured. Cultureindependent approaches such as using 16S metagenomics analysis provide a relatively unbiased view of the The polyphagous eri silk moth, Samia ricini, is associated with various symbiotic gut bacteria believed to provide several benefits to the host. The larvae of S. ricini were subjected to isolation of gut bacteria using culture-dependent 16S rRNA generic characterization, metagenomics analysis and qualitative enzymatic assays. Sixty culturable aerobic gut bacterial isolates comprising Firmicutes (54%) and Proteobacteria (46%); and twelve culturable facultative anaerobic bacteria comprising Proteobacteria (92%) and Firmicutes (8%) were identified inhabiting the gut of S. ricini. The results of metagenomics analysis revealed the presence of a diverse community of both culturable and un-culturable gut bacteria belonging to Proteobacteria (60%) and Firmicutes (20%) associated with seven orders. An analysis of the results of culturable isolation indicates that these bacterial isolates inhabited all the three compartments of the gut. Investigation on persistence of bacteria coupled with metagenomics analysis of the fifth instar suggested that bacteria persist in the gut across the different instar stages. In addition, enzymatic assays indicated that 48 and 75% of culturable aerobic, and 75% of anaerobic gut bacterial isolates had cellulolytic, lipolytic and nitrate reductase activities, thus suggesting that they may be involved in food digestion and nutritional provision to the host. These bacterial isolates may be good sources for profiling novel genes and biomolecules for biotechnological application.

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