Bio-Monitoring of heavy metal resistance in pseudomonas and pseudomonas related genus

Abstract

The aim of present study was to determine the level of heavy metal resistance patterns and to determine if there is a relationship between heavy metal resistance and plasmid presence. From 28 identified strains, 39.3% corresponded to Stenotrophomonas maltophilia, 17.9% to Chryseomonas luteola, 14.3% to Pseudomonas fluorescens, 10.7% to Pseudomonas putida, 7.1% to Sphingomonas paucimobilis, 7.1% to Methylobacterium mesophilicum and 3.6% Pseudomonas stutzeri. The resistance of these Gram negative bacteria to 8 heavy metals, was investigated by agar dilution method. Most isolates showed tolerance to different concentrations of heavy metals, and minimal inhibition concentrations ranged from 0,005 mmol-1 -20 mmol-1 . All strains displayed high resistance to zinc and lead (100% and 96,4% respectively) and high susceptibility to silver, cobalt and mercury (92.9%, 92.9% and 96.4% respectively). M. mesophilicum strains were determined as the most resistant strains to studied heavy metals. Isolated bacteria were tested for the presence of plasmids using the modified hot alkaline lysis method. The study also demonstrated that about 17.8% of isolated bacteria carried 0.89-21.59 kb sized plasmids and metal resistance profiles of bacteria carrying the same plasmids were similar. This study reveals the heavy metal resistance profiles of non-aeruginosa Pseudomonas species and other related species and the association between the occurrence of plasmids and the resistance to heavy metals.