title: Effect of acute and chronic arsenic exposure on growth, structure and virulence of Aeromonas hydrophila isolated from fish.
abstract: Aeromonas hydrophila being a ubiquitous bacterium is prone to arsenic exposure. The present study was designed to determine the role of arsenic on growth and virulence of A. hydrophila. Exposure to arsenic (1 mg L(-1) and 2 mg L(-1)) had no effect on growth but significantly inhibited the hemolytic and cytotoxic potential of exposed bacteria. Transmission electron microscopy revealed loss of membrane integrity and presence of condensed cytoplasm suggestive of acute stress in bacteria exposed to arsenic. Arsenic-adapted bacteria were developed by repeated sub-culturing in presence of arsenic. Arsenic-adaptation led to significant recovery in hemolytic and cytotoxic potential. The arsenic-adapted bacteria exhibited normal membrane integrity, decreased cytoplasmic condensation and possessed scattered polysome like structures in the cytoplasm. A positive correlation was observed between arsenic tolerance and resistance to several antimicrobials. Arsenic-adaptation failed to confer cross-protection to mercury and cadmium stress. SDS-PAGE analysis revealed the expression of two new proteins of approximately 85 kDa and 79 kDa respectively in arsenic-adapted A. hydrophila. Plasmid-curing and transformation studies clearly indicate plasmid has no role on arsenic resistance trait of the bacteria. Our study, for the first time, reports a structure and function relationship of xenobiotics on bacteria.
authors.affiliation: Immunobiology Laboratory, School of Life Sciences, Visva-Bharati University, Santiniketan, West Bengal, India.
authors.forename: Ramansu
authors.initials: R
authors.lastname: Goswami
authors.forename: Debabrata
authors.initials: D
authors.lastname: Ghosh
authors.forename: Dhira Rani
authors.initials: DR
authors.lastname: Saha
authors.forename: Pratap Kumar
authors.initials: PK
authors.lastname: Padhy
authors.forename: Shibnath
authors.initials: S
authors.lastname: Mazumder
mesh_terms: D016980:Aeromonas hydrophila / Q000187:drug effects / Q000254:growth & development* / Q000472:pathogenicity* / Q000648:ultrastructure; D000818:Animals; D001151:Arsenic / Q000633:toxicity*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002397:Catfishes / Q000382:microbiology*; D005393:Fish Diseases / Q000382:microbiology*; D014774:Virulence / Q000187:drug effects
chemical_list: D001426:Bacterial Proteins; D001151:Arsenic