Poly-extremophilic bacteria from high altitude Andean lakes: arsenic resistance profiles and biofilm production

Abstract

High levels of arsenic present in High Altitude Andean Lakes(HAAL) ecosystems have selected arsenic-resistant microbial communities which are of novel interest to study adaptations mechanisms which can be applied in bioremediation processes. We herein performed a detailedcharacterization of the arsenic tolerance profiles and the biofilm production oftwo HAAL poly-extremophiles, Acinetobacter sp. Ver3 (Ver3) and Exiguobacterium sp. S17 (S17). Cellular adherence over glass andpolypropylene surfaces were evaluated together with the effect of increasingdoses and oxidative states of arsenic over the quality and quantity of theirbiofilm production.The arsenic tolerance outcomes showed that HAAL strains couldtolerate higher arsenic concentrations than phylogenetically related strainsbelonging to the German collection of microorganisms and cell cultures(Deutsche Sammlung von Mikroorganismen und Zellkulturen, DSMZ), whichsuggest adaptations of HAAL strains to their original environment. On the otherhand, the crystal violet method (CV) and SEM analysis showed that Ver3 andS17 were able to attach to solid surfaces and to form the biofilm. Thequantification of biofilms production in 48 hours cultures through CV shows thatVer3 yielded higher production in the treatment without arsenic cultured on aglass support, while S17 yield higher biofilm production under intermediatearsenic concentration on glass supports. Polypropylene supports had negativeeffects on the biofilm production of Ver3 and S17. SEM analysis shows that the highest biofilm yields could be associated with a larger number of attached cells as well as the development of more complex 3D multicellular structures.