Molecular imprints of plant beneficial Streptomyces sp. AC30 and AC40 reveal differential capabilities and strategies to counter environmental stresses

Abstract

Streptomyces and their biomolecules are well explored for antibiotics production, bioremediation and alleviating the plant stresses due to their plant beneficial attributes. Therefore, due to plethora of biological attributes, the accurate portraying of molecular capabilities of these microorganisms at genomic level is of paramount importance. Here, we have evaluated biochemical attributes of two Streptomyces sp. AC30and AC40 for different plant beneficial activities which are antagonistic to Fusarium oxysporum, Alternaria solani, Sclerotinia sclerotium and Phytopthora infestans. In parallel, the draft genomes of these strains were deduced to understand their genomic capabilities using Illumina platform. The complete genome of AC30and AC40 were 11,284,599 bp and 12,636,188 bp in size with total G + C content of 62.36 and 54.75 %, respectively. Overall, higher number of genes (14,024) was reported for AC40 as compared to AC30 (12,476). The comparative genome organization revealed sharing of a few biosynthetic clusters as well as some exclusive biosynthetic clusters among both the strains. Further, expansion in the chitinases and glucanases was found in the genome of AC40. In addition, genes for 3-phytase and glycosyl hydrolase family 19 were restricted to AC40 only. The comparative genome study revealed presence of plant induced nitrilase in AC40 which is predicted for its role in IAA biosynthesis, release of ammonia, biotransformation of nitrile compounds to corresponding acids and bioremediation of soil containing nitrile compounds. For IAA and secondary metabolites biosynthesis, flavin-dependent monooxygenase, a rate limiting factor in Trp-dependent auxin biosynthesis pathway was found exclusive to AC30 genome. The comparative study revealed the diversification of few pathways/strategies to suppress plant pathogens and promote plant growth by Streptomyces strains.