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

Abstract

The high-altitude Andean Lakes (HAAL) areecosystems located in the South American Andes. These ecosystems are unique dueto their geographical characteristics, their broad range of extremeenvironments, as well their abundant biodiversity. Thegenus Exiguobacteriumis one of the most widespread and representative genera on the HAAL, beingdetected by direct (pure culture isolation) and indirect (DGGE) techniques. Thisgenera have been isolated or molecularly detected from a wide range of habitatsincluding cold and hot environments with temperature between-12 and 55°C. This fact confers substantial interest to the genus as apotential model system to research attributes that may correlate withadaptation and evolution of organisms to diverse thermalregimes. Exiguobacterium sp. S17 is a high arsenic resistantpolyextremophilic bacteria isolated from the stromatolites of L. Socompa. This strain is able to grow readily in laboratory and represents an attractive model system for the study of environmentalstress. Previous studies showed that Exiguobacterium sp. S17 is able to resistto high arsenic concentration and to produce biofilm. The aim of this work was toassess biofilms formation byExiguobacterium sp. S17 in different synthetic supports and to investigatethe influence of arsenic (As[III] y As[V]) in their development.Determination andquantification of biofilms was measured using crystal violet 1% following themethodology proposed by Tomaras et al., (2003). Biofilms production wasevaluated at different incubation times (24, 48 and 72 h) in LB50media (without As) and in different synthetic supports: sterile glass tubes (15x 125mm) and polypropylene (12 x 75 mm) and polystyrene plates (20 cm3).The influence of As was investigated supplemented LB50 with arsenate(As[V]): 50mM, 100 mM, 150 mM, 200mM, 250mM and arsenite (As[III]): 2.5 mM,5mM, 7.5 mM, 10 mM, 12.5 mM at the same time.ANOVA analyzes revealed that the optimal production of biofilms isachieved after 24 hours of growth and the highest biofilm production wasobtained when using glass as support 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 theknowledge of the biology and ecology of the microbial communities of the HAALin response to stress factors. Moreover, this method can be applied for thebenefit of human and environmental health by establishing an experimental basisfor a bioremediation method. Furthermore, we propose that HAAL is a source of novelbacterial species of biotechnological interest.