Whole genome sequencing and comparative genomic analyses of Pseudomonas aeruginosa strain isolated from arable soil reveal novel insights into heavy metal resistance and codon biology.

Elevated concentration of non-essential persistent heavy metals and metalloids in the soil is detrimental to essential soil microbes and plants, resulting in diminished diversity and biomass. Thus, isolation, screening, and whole genomic analysis of potent strains of bacteria from arable lands with inherent capabilities of heavy metal resistance and plant growth promotion hold the key for bio remedial applications. This study is an attempt to do the same. In this study, a potent strain of Pseudomonas aeruginosa was isolated from paddy fields, followed by metabolic profiling using FTIR, metal uptake analysis employing ICP-MS, whole genome sequencing and comparative codon usage analysis. ICP-MS study provided insights into a high degree of Cd uptake during the exponential phase of growth under cumulative metal stress to Cd, Zn and Co, which was further corroborated by the detection of cadA gene along with czcCBA operon in the genome upon performing whole-genome sequencing. This potent strain of Pseudomonas aeruginosa also harboured genes, such as copA, chrA, znuA, mgtE, corA, and others conferring resistance against different heavy metals, such as Cd, Zn, Co, Cu, Cr, etc. A comparative codon usage bias analysis at the genomic and genic level, whereby several heavy metal resistant genes were considered in the backdrop of two housekeeping genes among 40 Pseudomonas spp. indicated the presence of a relatively strong codon usage bias in the studied strain. With this work, an effort was made to explore heavy metal-resistant bacteria (isolated from arable soil) and whole genome sequence analysis to get insight into metal resistance for future bio remedial applications.