Molecular phylogeny, enzymatic profile, plant growth promotion and bioremediation capabilities of psychrotolerant Pseudomonas fragi strain AC isolated from an Antarctic freshwater lake

Microorganisms isolated from Antarctic lake waters attract special attention as valuable resources for biotechnological applications. Herein, we investigated the phylogeny, biochemical properties, and functional traits of the AC strain, isolated from lake water sample on Ardley Island, Antarctica. Phylogenetic analysis were conducted using both the 16S rRNA and multilocus sequence analysis (MLSA) including 16S rRNA, gyrB, rpoB, and rpoD genes. These methods yielded phylogenetic trees that revealed 99.78 % similarity between the AC strain and Pseudomonas fragi. The AC strain deposited in NCBI GenBank under accession number OR150484, is a psychrotrophic and alkali-tolerant bacterium capable of growth at temperatures from 4 °C to 30 °C and pH levels from 5.0 to 10.0, though it is sensitive to NaCl. Functionally, the strain demonstrated the ability to biodegrade diesel fuel at concentrations of 1–5 %, though no kerosene degradation was detected. Plant growth-promoting (PGP) traits such as indole-acetic acid (IAA) and siderophore production were observed, along with proteolytic and lipolytic enzymatic activities. The strain exhibited the tolerance to selected heavy metals in with an order of Pb(II) > Cu(II) > Cr(III) > Zn(II) > Ni(II) > Cd(II). These findings highlight the potential of P. fragi strain AC in biotechnological applications including bioremediation and PGP.