Occurrence of resistance to antibiotics, UV-B and arsenic in bacteria isolated from extreme environments in high altitude (above 4400m) Andean wetlands

JULIAN DIB; JESSICA MOTOK; VERONICA FERNANDEZ ZENOFF; OMAR F. ORDOÑEZ; MARIA E. FARIAS

CURRENT MICROBIOLOGY

Springer

Lugar: New York; Año: 2008 p. 510 - 517

0343-8651

Abstract High altitude Andean wetlands represents an environment with extreme conditions like high UV incidence, metal content (mainly arsenic), high salinity, oligotrophy, etc. Bacteria isolated from Laguna Vilama (4,400m altitude) were phylogeneticaly identified and, together with those previous identified from Laguna Azul (4,560 m altitude), their resistance to UV-B and tolerance to arsenic were achieved. In addition multiple antibiotics resistances were also determined in order to establish a probably relationship between antibiotic resistances as a consequence of mutagenic ability or in relation to metal resistance. As in Laguna Azul, Gram-positive bacteria predominance was also found between the culturable isolates from Laguna Vilama (Bacillus (vegetative) (2) Staphylococcus (1) Actinomycetes (3) and gamma proteobacteria (1)). High UV-B resistances were determined, since after 15 min (347,27 J m-2 ) and 30 min (694,54 J m-2) irradiation most of the studied bacteria did not decreased their survival, what is more, many of them improved their survival with the increase doses. Augment in mutagenesis rates were observed after UV-B irradiation. Arsenate tolerance was also established in half of the tested isolates. Extreme resistances were found in Staphylococcus saprophyticus A3 and Micrococcus sp. A7 which were able to growth in media containing up to 600 mM arsenate. Finally predominance of antibiotic resistances (Azithromicyn, Erythromycin, Clarithromycin, Roxithromycin, Streptomycin, Chloramphenicol, Gentamicin, Kanamicine, Tetracicline and Ampiciline) were found, in all the isolate d strains, with unexpected high minimal inhibitory concentrations (MICs) > 2 mg mL-1 for macrolides. These results would demonstrate that in extreme environments like high altitude wetlands there is a correlation of multiresitances to UV-B radiation and arsenate, and that ATB resistances , are also wide spread in thesepristine environments, where ATB selective pressure, is supposed to be absent. This could be probably asconsequence of mutagenic increase after UV-B irradiation or in relation to arsenic resistance.