Rup Lal
University of Delhi, India
Title: Predatory-prey dynamics of novel genotypes enriched across arsenic-rich Himalayan hot springs
Biography
Biography: Rup Lal
Abstract
Metagenomic diversity analysis across microbial mats deposited surrounding thermal discharges of Manikaran hot springs located atop the Himalayan ranges in Himachal Pradesh, India (with surface temp. >95 °C) highlighted the genetic predominance of novel Bdellovibrio bacteriovorus genotypes as the primary bacterial predator and Enterobacter cloacae as the eco-genetically adapted host. While B. bacteriovorus has been characterized from mesophilic environments (soil, marine and freshwater, etc.), these communities are not amenable to metagenomic re-assembly of predatory and prey genotypes due to high taxonomic diversity and community evenness. Here, we present the first metagenomic analysis of the microbial mats of an arsenic rich (140 ppb) hot spring in which these predator-prey genotypes were characterized. The microbial mats were enriched with Bdellovibrio and several gram-negative bacteria including Bordetella (16%), Enterobacter (6.8%), Burkholderia (4.8%), Acinetobacter (2.3%), and Yersinia (1%). A high quality (53 contigs, 25X coverage; 3.5 Mbp) draft genome of B. bacteriovorus (strain ‘ArHS’) was re-assembled, which lacked the marker gene bd0108 associated with the established method of prey interaction and invasion, while still maintaining genes coding for the hydrolytic enzymes necessary for prey assimilation. By filtering microbial mat samples (<0.45 μm) to enrich for small predatory cell sizes we observed Bdellovibrio-like cells attached side-on to E. coli. Furthermore, a draft pan-genome of the dominant host taxon, Enterobacter cloacae ArHS, (4.8 Mb), along with three of its viral genotypes (n=3; 42, 49 and 50 kb) were assembled. These data were used to construct a theoretical model describing potential predator avoidance strategies, whereby the E. cloacae strains can move between anaerobic and aerobic niches by quorum sensing population size, which is modulated by a ‘kill-the-winner’ viral mechanism, and predation by the obligate aerobe, B. bacteriovorus.