Unlocking the potential of insect and ruminant host symbionts for recycling of lignocellulosic carbon with a biorefinery approach: a review

Gunasekaran Rajeswari,Vinod Kumar,Samuel Jacob,Anuj Kumar Chandel

doi:10.1186/s12934-021-01597-0

Abstract

Uprising fossil fuel depletion and deterioration of ecological reserves supply have led to the search for alternative renewable and sustainable energy sources and chemicals. Although first generation biorefinery is quite successful commercially in generating bulk of biofuels globally, the food versus fuel debate has necessitated the use of non-edible feedstocks, majorly waste biomass, for second generation production of biofuels and chemicals. A diverse class of microbes and enzymes are being exploited for biofuels production for a series of treatment process, however, the conversion efficiency of wide range of lignocellulosic biomass (LCB) and consolidated way of processing remains challenging. There were lot of research efforts in the past decade to scour for potential microbial candidate. In this context, evolution has developed the gut microbiota of several insects and ruminants that are potential LCB degraders host eco-system to overcome its host nutritional constraints, where LCB processed by microbiomes pretends to be a promising candidate. Synergistic microbial symbionts could make a significant contribution towards recycling the renewable carbon from distinctly abundant recalcitrant LCB. Several studies have assessed the bioprospection of innumerable gut symbionts and their lignocellulolytic enzymes for LCB degradation. Though, some reviews exist on molecular characterization of gut microbes, but none of them has enlightened the microbial community design coupled with various LCB valorization which intensifies the microbial diversity in biofuels application. This review provides a deep insight into the significant breakthroughs attained in enrichment strategy of gut microbial community and its molecular characterization techniques which aids in understanding the holistic microbial community dynamics. Special emphasis is placed on gut microbial role in LCB depolymerization strategies to lignocellulolytic enzymes production and its functional metagenomic data mining eventually generating the sugar platform for biofuels and renewable chemicals production.

Highlights

In the field of renewable energy, bioconversion of lignocellulosic biomass (LCB) attempts to substantiate the earths carbon recycling by creating a green biorefinery approach
First study on the functional characterization was performed by Suen et al [43], where the metagenomic data of CAZymes from leaf-cutter ants microbiome revealed the contribution of diverse gut bacterial symbionts in the LCB degradation
Several xylophagous insects and herbivores animals have been discovered as a potent source for LCB bioconversion owing to its synergistic symbionts

Summary

Introduction

In the field of renewable energy, bioconversion of lignocellulosic biomass (LCB) attempts to substantiate the earths carbon recycling by creating a green biorefinery approach. Auer et al [31], revealed the LCB degrading potency of xylophages termite gut microflora which includes an anaerobic bioreactor-based enrichment strategy for gut microbial community using wheat straw as a primary carbon source for its bioconversion into carboxylates. Exploring the microbial communities of natural biomass utilization system (insects and ruminants) using high throughput metagenomic DNA sequencing provides a notable insight into the functional characterization of gut microbiome.

Results

Conclusion