title: Purple non-sulfur photosynthetic bacteria monitor environmental stresses.
abstract: Heavy metal ion pollution and oxygen deficiency are major environmental risks for microorganisms in aqueous habitat. The potential of purple non-sulfur photosynthetic bacteria for biomonitoring and bioremediation was assessed by investigating the photosynthetic capacity in heavy metal contaminated environments. Cultures of bacterial strains Rhodobacter sphaeroides, Rhodospirillum rubrum and Rubrivivax gelatinosus were treated with heavy metal ions in micromolar (Hg(2+)), submillimolar (Cr(6+)) and millimolar (Pb(2+)) concentration ranges. Functional assays (flash-induced absorption changes and bacteriochlorophyll fluorescence induction) and electron micrographs were taken to specify the harmful effects of pollution and to correlate to morphological changes of the membrane. The bacterial strains and functional tests showed differentiated responses to environmental stresses, revealing that diverse mechanisms of tolerance and/or resistance are involved. The microorganisms were vulnerable to the prompt effect of Pb(2+), showed weak tolerance to Hg(2+) and proved to be tolerant to Cr(6+). The reaction center controlled electron transfer in Rvx. gelatinosus demonstrated the highest degree of resistance against heavy metal exposure.
authors.affiliation: Department of Medical Physics, University of Szeged, Hungary.
authors.forename: Mariann
authors.initials: M
authors.lastname: Kis
authors.affiliation: Department of Medical Physics, University of Szeged, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Sipka
authors.affiliation: Department of Medical Physics, University of Szeged, Hungary.
authors.forename: Emese
authors.initials: E
authors.lastname: Asztalos
authors.affiliation: Department of Pathology, University of Szeged, Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Rázga
authors.affiliation: Department of Medical Physics, University of Szeged, Hungary. Electronic address: pmaroti@sol.cc.u-szeged.hu.
authors.forename: Péter
authors.initials: P
authors.lastname: Maróti
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001429:Bacteriochlorophylls / Q000378:metabolism; D002857:Chromium / Q000633:toxicity; D054750:Ecotoxicology / Q000379:methods; D004784:Environmental Monitoring / Q000379:methods; D005453:Fluorescence; D007854:Lead / Q000633:toxicity; D008628:Mercury / Q000633:toxicity; D019216:Metals, Heavy / Q000633:toxicity*; D010788:Photosynthesis; D012242:Rhodobacter sphaeroides / Q000187:drug effects / Q000502:physiology*; D012241:Rhodopseudomonas / Q000187:drug effects / Q000502:physiology*; D012247:Rhodospirillum rubrum / Q000187:drug effects / Q000502:physiology*; D013045:Species Specificity; D013312:Stress, Physiological; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D001429:Bacteriochlorophylls; D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; D002857:Chromium; D007854:Lead; D008628:Mercury
keywords: Anaerobism; Biomonitoring; Bioremediation; Fluorescence induction; Heavy metal toxicity; Purple bacteria