title: Fluctuation in recoverable nickel and zinc resistant copiotrophic bacteria explained by the varying zinc ion content of Torsa River in different months.
abstract: Heavy metal content analysis of River Torsa in India did not indicate any alarming level of toxicity for human consumption but revealed variation at the ppb level in different months. The variation in recoverable nickel and zinc resistant copiotrophic (or eutrophic) bacterial counts was explained by the variation of the zinc content (34.0-691.3 ppb) of the river water in different sampling months. Growth studies conducted with some purified nickel and/or zinc resistant strains revealed that pre-exposure of the cells to ppb levels of Zn(2+), comparable to the indigenous zinc ion concentration of the river, could induce the nickel or zinc resistance. A minimum concentration of 5-10 microM Zn(2+ )(325-650 ppb) was found effective in inducing the Nickel resistance of the isolates. Zinc resistance of the isolates was tested by pre-exposing the cells to 4 microM Zn(2+ )(260 ppb). The lag phase was reduced by 6-8 h in all the cases. Biochemical characteristics and phylogenetic analysis based on 16S rDNA sequence indicated that some of the Torsa River isolates, having inducible nickel and zinc resistance, are members of the genus Pseudomonas, Acinetobacter, Bacillus, Enterobacter, Serratia and Moraxella.
authors.affiliation: Department of Biotechnology, North Bengal University, Siliguri 734430, West Bengal, India.
authors.forename: Bhaskar
authors.initials: B
authors.lastname: Bhadra
authors.forename: Ashis Kumar
authors.initials: AK
authors.lastname: Nanda
authors.forename: Ranadhir
authors.initials: R
authors.lastname: Chakraborty
mesh_terms: D000150:Acinetobacter / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D001407:Bacillus / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D001419:Bacteria / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D001483:Base Sequence; D004754:Enterobacter / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D007194:India; D008969:Molecular Sequence Data; D009016:Moraxella / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D009532:Nickel / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D010802:Phylogeny; D011549:Pseudomonas / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D045483:Rivers; D012705:Serratia / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D015032:Zinc / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D009532:Nickel; D015032:Zinc