caa a22 4500 445321628 CHVBK 20180317142705.0 cr unu---uuuuu 170323e20110601xx s 000 0 eng 10.1007/s10534-011-9446-1 doi (NATIONALLICENCE)springer-10.1007/s10534-011-9446-1 Chromium resistance strategies and toxicity: what makes Ochrobactrum tritici 5bvl1 a strain highly resistant [Elektronische Daten] [Paula Morais, Rita Branco, Romeu Francisco] Large-scale industrial use of chromium (Cr) resulted in widespread environmental contamination with hexavalent chromium (Cr(VI)). The ability of microorganisms to survive in these environments and detoxify chromate requires the presence of specific resistance systems. Several Cr(VI) resistant species, belonging to a variety of genera, have been isolated in recent years. Ochrobactrum tritici strain 5bvl1 is a model for a highly Cr(VI)-resistant and reducing microorganism, with different strategies to cope with chromium. The strain contains the transposon-located (TnOtChr) chromate resistance genes chrB, chrA, chrC, chrF. The chrB and chrA genes were found to be essential for the establishment of high resistance but not chrC or chrF genes. Other mechanisms involved in chromium resistance in this strain were related to strategies such as specific or unspecific Cr(VI) reduction, free-radical detoxifying activities, and repairing DNA damage. Expression of the chrB, chrC or chrF genes was related to increased resistance to superoxide-generating agents. Genetic analyses also showed that, the ruvB gene is related to chromium resistance in O. tritici 5bvl1. The RuvABC complex probably does not form when ruvB gene is interrupted, and the repair of DNA damage induced by chromium is prevented. Aerobic or anaerobic chromate reductase activity and other unspecific mechanisms for chromium reduction have been identified in different bacteria. In the strain O. tritici 5bvl1, several unspecific mechanisms were found. Dichromate and chromate have different effects on the physiology of the chromium resistant strains and dichromate seems to be more toxic. Toxicity of Cr(VI) was evaluated by following growth, reduction, respiration, glucose uptake assays and by comparing cell morphology. Springer Science+Business Media, LLC., 2011 Chromium nationallicence Chromate nationallicence Dichromate nationallicence Toxicity nationallicence Resistant bacteria nationallicence Morais Paula Department of Life Sciences, FCTUC, University of Coimbra, 3001-401, Coimbra, Portugal aut Branco Rita IMAR-CMA, 3004-517, Coimbra, Portugal aut Francisco Romeu IMAR-CMA, 3004-517, Coimbra, Portugal aut BioMetals Springer Netherlands 24/3(2011-06-01), 401-410 0966-0844 24:3<401 2011 24 10534 https://doi.org/10.1007/s10534-011-9446-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10534-011-9446-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Morais Paula Department of Life Sciences, FCTUC, University of Coimbra, 3001-401, Coimbra, Portugal aut NATIONALLICENCE 700 1- Branco Rita IMAR-CMA, 3004-517, Coimbra, Portugal aut NATIONALLICENCE 700 1- Francisco Romeu IMAR-CMA, 3004-517, Coimbra, Portugal aut NATIONALLICENCE 773 0- BioMetals Springer Netherlands 24/3(2011-06-01), 401-410 0966-0844 24:3<401 2011 24 10534 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer