Metagenomic profiling of thermal aquatic niches of the Sikkim Himalayas and characterization of novel pectin transforming biocatalysts

Abstract

This doctoral study investigated the genetic resources of the Himalayan thermal springs by doing in-depth metagenomic investigations, revealing microbial community structure, the prevalent metabolic pathways, and identifying genetic resources of industrially important biocatalysts. The construction of metagenome assembled genomes (MAGs) envisaged novel microbial species in the thermal aquatic habitats. The molecular determinants of antibiotic, biocide, and metal co-resistomes for the dissemination of resistance conferring genes were predicted as the syntenic blocks in MAGs. Functional profiling depicted the carbohydrate-active enzyme weaponry with a special emphasis on pectin-transforming biocatalysts in the hot springs of the Sikkim Himalayas. A novel gene for pectate lyase (EPLM) was identified and characterized from the Reshi hot spring metagenome. The biochemical characterization established that it is tolerant to alkaline conditions (e.g. pH 11.0-12.0). It was employed for the bioscouring application of pectin-containing biomass, such as banana pseudostem. Furthermore, an acidic mine tailing metagenome was mined for a novel endopolygalacturonase (EPHM) enzyme variant. EPHM was found to be a thermostable as well as a metal-tolerant enzyme. EPHM was competent in generating pectic oligosaccharides from methylated biomass pectin and from unmethylated polygalacturonic acid. newline