metal tolerance

  The present study deals with isolation, identification and characterization of heavy metal resistant bacteria isolated from sewage water collected in and around Trichy district, South India. Initially, among 26 of the total isolates screened from sewage water, one isolate was selected for study based on high level of heavy metal resistances. On the basis of morphological, biochemical, 16S rDNA gene sequencing and phylogeny analysis revealed that, the isolate was authentically identified as Pseudomonas aeruginosa. The sewage isolate exhibited resistance to Silver (Ag), Copper (Cu) and Zinc (Zn). The maximum tolerance concentration (MTC) of the isolate against Ag, Cu and Zn was determined in solid media. The uptake of heavy metals, present in sewage and detoxification of metal ions by bacteria provide an additional mechanism of environmental bioremediation. The identified heavy metal resistant bacteria could be useful for the bioremediation of heavy metal contaminated sewage and waste water. Key words: Heavy metals; copper; silver; zinc; metal tolerance

  With an intention to screen for bacterial isolates from wound infection exhibiting resistance to antibiotics, we also checked for the resistance to heavy metals, since both may be plasmid borne. Several bacteria have naturally developed tolerance to a wide range of antibiotics and toxic heavy metals. Some bacteria have also evolved mechanisms to detoxify heavy metals. Tolerance of zinc and copper by these bacteria were studied and it was found that gram positive bacteria were more resistant than gram negative bacteria. We could determine the common pattern of resistance of the isolates to both antibiotics and metals. Key words: antibiotics; heavy metals; copper; zinc; metal tolerance