Compost Samples from Different Temperature Zones as a Model to Study Co-occurrence of Thermophilic and Psychrophilic Bacterial Population: a Metagenomics Approach.

In this study, using a metagenomic approach, we explore the bacterial diversity of compost sites categorized based on their ambient temperatures. The two sites were Reckong Peo in the lower Himalayas and Tambaram in the southern region of the country, namely, CPR and CT. Following assembly of the raw reads from shotgun metagenomics, similarity hits were generated using NCBI BLAST + and SILVA database. A total of 1463 and 1483 species were annotated from CPR and CT. A species-level annotation was performed using a python-based literature search pipeline revealing their growth characteristics. Thermophiles Thermomonospora curvata and Thermus scotoductus were among the prominent species in CT. CPR too was seen abundant with Acidothermus cellulolyticus and Moorella thermoacetica, constituting 10% of the population. Nearly 3% of the identified species in the site CPR were psychrophilic. Although found higher in CPR, psychrophilic species were identified in CT too. Flavobacterium and Psychrobacter spp. were present in both sites without any significant changes in their relative distribution contrary to the thermophilic species abundance (z = - 4.3). Akin to the sequenced samples, database-derived metagenomes also showed similar distribution of thermophiles and psychrophiles. Identifying such peculiar prevalence of extremophiles can be central to understanding extended growth temperatures.