Pseudomonas aeruginosa strain WI-1 from Mandovi estuary possesses metallothionein to alleviate lead toxicity and promotes plant growth

A bacterial isolate from Mandovi estuary Goa, India, which can resist 0.6 mM lead nitrate in Tris-buffered minimal medium was identified as Pseudomonas aeruginosa and designated as strain WI-1. PCR amplification clearly revealed presence of bmtA gene encoding bacterial metallothionein responsible for metal sequestration and AAS analysis proved intracellular bioaccumulation of 26.5 mg lead/gram dry weight of cells. SDS-PAGE analysis confirmed lead induced bacterial metallothionein with molecular weight 11 kDa, which corresponds to the predicted bmtA gene. Significant growth inhibition of phytopathogenic fungi Fusarium oxysporum NCIM 1008 by siderophore-rich culture supernatant was also observed. Pot experiment with Pisum sativum L inoculated with this strain revealed higher seed germination percentage and significant growth promotion than uninoculated seeds in a soil amended with 7.704 g/kg lead, which indicates amelioration of lead toxicity. This lead resistant strain showed cross tolerance to cadmium, mercury and Tributyltin chloride (TBTC) along with resistance to multiple antibiotics.

► The lead resistant Pseudomonas aeruginosa possessed bacterial metallothionein (BmtA).
► Intracellular bioaccumulation of lead was 26.5 mg per gram dry weight of cells.
► Siderophore rich supernatant inhibited growth of the Fusarium oxysporum NCIM 1008.
► The test bacterium reduced lead uptake in Pisum sativum and promoted its growth.