The biofilms formation of Exiguobacterium sp. S17 on synthetic supports and under the influence of arsenic.

OMAR F. ORDOÑEZ; FEDERICO ZANNIER; VIRGINIA H. ALBARRACÍN; FARÍAS, MARÍA EUGENIA

Congreso; XI Congreso Argentino de Microbiología General SAMIGE; 2015

The high-altitude Andean Lakes (HAAL) are ecosystems located in the South American Andes. These ecosystems are uniquedue to their geographical characteristics, their broad range of extreme environments, as well their abundant biodiversity. Thegenus Exiguobacterium is one of the most widespread and representative genera on the HAAL, being detected by direct (pureculture isolation) and indirect (DGGE) techniques. This genera have been isolated or molecularly detected from a wide range ofhabitats including cold and hot environments with temperature between -12 and 55°C. This fact confers substantial interest tothe genus as a potential model system to research attributes that may correlate with adaptation and evolution of organisms todiverse thermal regimes. Exiguobacterium sp. S17 is a high arsenic resistant polyextremophilic bacteria isolated from thestromatolites of L. Socompa. This strain is able to grow readily in laboratory and represents an attractive model system for thestudy of environmental stress. Previous studies showed that Exiguobacterium sp. S17 is able to resist to high arsenicconcentration and to produce biofilm. The aim of this work was to assess biofilms formation by Exiguobacterium sp. S17 indifferent synthetic supports and to investigate the influence of arsenic (As[III] y As[V]) in their development. Determination andquantification of biofilms was measured using crystal violet 1% following the methodology proposed by Tomaras et al., (2003).Biofilms production was evaluated at different incubation times (24, 48 and 72 h) in LB50 media (without As) and in differentsynthetic supports: sterile glass tubes (15 x 125mm) and polypropylene (12 x 75 mm) and polystyrene plates (20 cm3). Theinfluence of As was investigated supplemented LB50 with arsenate (As[V]): 50mM, 100 mM, 150 mM, 200mM, 250mM andarsenite (As[III]): 2.5 mM, 5mM, 7.5 mM, 10 mM, 12.5 mM at the same time. ANOVA analyzes revealed that the optimalproduction of biofilms is achieved after 24 hours of growth and the highest biofilm production was obtained when using glass assupport and adding arsenate (As [V]100 mM). No significant differences were observed when adding arsenite in comparison tocontrol medium (without arsenic). The findings obtained in this work made an important contribution to the knowledge of thebiology and ecology of the microbial communities of the HAAL in response to stress factors. Moreover, this method can beapplied for the benefit of human and environmental health by establishing an experimental basis for a bioremediation method.Furthermore, we propose that HAAL is a source of novel bacterial species of biotechnological interest.