Prospecting Cellulolytic Bacteria From White Grubs (Holotrichia serrata (F.) and Leucopholis coneophora Burmeister) Native to Karnataka Region

Abstract

Abstract Background Insecta, the largest class within Arthropoda, hosts complex symbiotic relationships with microorganisms, offering significant potential for various biotechnological applications. The gut microbiota of insects, comprising a diverse array of bacteria, plays crucial roles in food digestion, nutrient provisioning, and enzyme synthesis, particularly relevant for lignocellulosic biomass breakdown and bioremediation. White grubs that are significant pests in Karnataka region, such Holotrichia serrata and Leucopholis coneophora, have gut microbiota that are rich in cellulolytic bacteria, which significantly aid in the breakdown of cellulose. Lignocellulosic biomass, derived from agricultural and forestry waste, presents opportunities for sustainable biofuel production and waste management. Results Seventeen cellulolytic bacterial isolates were obtained from the fermentation chambers of white grubs, displaying diverse morphological characteristics and predominantly belonging to Firmicutes and γ-proteobacteria. Bacillus, Enterobacter and Klebsiella species were prevalent among the isolates. Evaluation of cellulolytic activity revealed notable capabilities, with Bacillus toyonensis strain LC3B1 exhibiting remarkable cellulolytic index. Substrate degradation assays demonstrated LC3B1 proficiency in decomposing various agricultural residues, highlighting its potential in biomass conversion. Structural analyses using FTIR and SEM techniques provided insights into cellulose breakdown mechanisms by these isolates. Conclusion The study underscores the diverse cellulolytic capabilities harbored within the gut bacteria of white grubs, offering promising avenues for biotechnological applications in lignocellulosic biomass degradation and biofuel production. The ubiquity of cellulase-producing strains from families such as Bacillaceae, Enterobacteriaceae, and Pseudomonadaceae highlights their vital role in the degradation of lignocellulosic biomass, having noteworthy consequences for the utilisation of biodegradation in recycling and environmentally friendly waste disposal.