A metagenomic investigation of microbial consortia underpinning anaerobic digestion for renewable biogas production

Abstract

Anaerobic digestion (AD), as one of the oldest human biotechnology, has attracted revived research focus on the underpinning biological principle in recent years due to its potential in renewable green energy. With the assistance of the latest 454 deep sequencing technology, two independent studies were conducted with a shared goal to understand the operational influences on the AD microbiology from the unprecedented depth and breadth of genetic information. The first study aimed to decipher the contribution of a newly-devised waste sludge pretreatment method, which promised significant improvement in downstream biogas production. The first application of whole genome metagenomic approach on this topic revealed extensive shifts in both microbial and functional consortia towards higher biodegradation after pretreatment; meanwhile dominant acetoclastic and hydrogenotrophic methanogenesis pathways were identified concurrently with an alternative enzymology in Methanosaeta. The second study focused on the temporal dynamics of bacteria residing in production-scale biogas bioreactor coupled with multiple-sampling strategy for a realistic description of the actual microbial structure. Both bacterial fingerprint marked by feedstock and evolutionary drive towards biodegradation were revealed by 16S rDNA amplicon multiplex pyrosequencing, where clustering analyses further delineated the taxonomic plasticity and functional resilience of the bacterial communities over time. Phylogeny coverage of the highly diverse population was also improved by the adopted strategy, providing insights for sampling and sequencing standards. Altogether, the combined results garnered knowledge enrichment to the relationship between AD microbiology and operational parameters, which will assist the design of more efficient bioenergy platform in future.