Biotechnological approaches in agriculture and environmental management - bacterium Kocuria rhizophila 14ASP as heavy metal and salt- tolerant plant growth- promoting strain

Abstract

Plant growth-promoting bacteria (PGPB), possess multifarious beneficial traits and facilitate plant growth by both direct and indirect mechanisms under hostile conditions. The objective of the current study was to evaluate the potential application of 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase) producing plant-growth promoting endophyte bacterium (PGPEB) Kocuria rhizophila strain 14ASP (National Center for Biotechnology Information; NCBI) Accession Number: LFIY00000000.1) heavy metals and salt resistance tolerance under hostile environment. The in vitro study was conducted to evaluate plant growth promotion characteristics, heavy metal and salt resistance of the K. rhizophila under normal and stressful environments. The strain 14ASP revealed the plant-growth promoting and of AAC deaminase activities under abiotic stress environment. K. rhizophila showed significant tolerance against different heavy metals on LB (Luria Ber-tani) agar plates and broth medium supplemented with cadmium (Cd), (50 mg L−1), cooper (Cu), (50 mg L−1), nickel (Ni), (50 mg L−1), lead (Pb), (200 mg L−1) and chromium (Cr) (500 mg L−1), respectively. It also exhibited population density (OD = 0.31–0.45) at different concentrations of sodium chloride (NaCl) (0% 5%, 10%, and 15% w/v) in LB medium. The draft genome of strain 14ASP is 2.6 Mb and was assembled into 183 contigs with 2689,1 bp and a G + C content of 70% and 1,882,646 bp, encoded 2409 protein, 8 rRNAs and 46 tRNAs. Genome analysis identified genes, involved in hydrocarbon metabolism, heavy metal tolerance, biofilm formation, Indole Acetic Acid (IAA) and siderophore biosynthesis. All these properties were confirmed by in silico and draft genome analysis.