Isolation and identification of potent tributyltin chloride utilizing Pseudomonas sp. strain VBAK from Vishakhapatnam shipping harbor sediments

Abstract

Screening for tributyltin (TBT)-resistant and degrading bacteria was pertinent for the selection of isolates with decontamination ability of TBT. With this rationale, 205 strains were isolated from Vishakhapatnam shipping harbor sediments and their tolerance limit to TBT was evaluated in minimal salts media containing 2 mM TBT as the sole carbon source. Fourteen selective TBT-resistant isolates showed cross-tolerance to heavy metals and antibiotics. Among them, one interesting isolate VBAK, showing the highest TBT resistance and maximum growth yield, was selected and taxonomic identification was carried out by sequencing 16S rRNA gene. The maximum composite likelihood algorithm formed a coherent cluster with clad comprised Pseudomonas sp. The thin-layer chromatography profile of the degradation product revealed the depletion of TBT into dibutyltin. The Rf values of TBT and transformed compounds were 0.8 (solvent front = 16.5 plus or minus 2, TBT 9.1 plus or minus 1.0) and 0.7 (solvent front = 6.5 plus or minus 2, product 6.8 plus or minus 2), respectively. These results suggest that Pseudomonas sp. strain VBAK is potentially useful for bioremediation of TBT contamination.