Diversity of Cellulolytic Bacteria from the Digestive Tract of Oryctes rhinoceros Larvae

Abstract

Lignocellulose is a ubiquitous biopolymer that, once degraded into monomeric products, could be used to produce a wide range of products. Bioconversion using indigenous microbes could be a solution to the large array of cellulosic waste and it could be sourced from exotic organisms such as Asiatic rhinoceros beetle (Oryctes rhinoceros L). This study aimed to cellulolytic bacteria from the digestive tract of Oryctes rhinoceros larvae verify their cellulolytic abilities and identify the species based on 16S rRNA. Seven isolates were purified from the larvae and all were able to hydrolyze cellulose with the highest cellulolytic index displayed by isolate B01L (1.28), while the lowest by B06L (0.15). The highest cellulase activity assayed using the 3,5-Dinitrosalicylic acid (DNS) method was produced by B01L at 0.010 U/mL. Molecular identification using 16S rRNA assigned seven species as Bacillus tequilensis strain B01L, Bacillus pacificus strain B02L, Serratia marcescens strain B03L, Lysinibacillus fusiformis strain B04L, Lactococcus geraviae strain B05L, Pseudomonas monteilii strain B06L and Priestia aryabhattai strain B07L. All bacterial genera from the digestive tract had the ability to degrade cellulose. Then the result suggests that all bacteria have an important role in cellulose degradation and may have mutualistic traits with the host, such as cellulose bioconversion.