High-Altitude Andean Lakes as a hidden source for extreme actinobacteria of biotechnological interest

ALBARRACÍN V.H.; FARIAS M.E.

Puerto Vallarta

Simposio; 16TH INTERNATIONAL SYMPOSIUM ON THE BIOLOGY OF ACTINOMYCETES; 2011

ISBA Board

Actinobacteria, Gram positive high GC bacteria (50- 71%), are widely distributed in both terrestrial and aquatic ecosystems, especially in soil, where they play a crucial nutrient recycling role. Novel actinobacteria has been reported in marine sediments and as marine invertebrate symbionts. But fewer reports on actinobacterial strains from extreme environments have been performed. In this work, we highlight the potential of the extreme environments of the High-Altitude Andean Lakes (HAALs) at the northwest of Argentina (from 3,000 to 6,000 masl) as a new source of novel actinobacteria of biotechnological interest. In the course of several sampling expeditions to the HAAL performed since 2002, we have isolated and classify more than 400 prokaryotic strains, including archaea, eubacteria and cyanobacteria. Actinobacteria are an important group within our collection with ca. 150 strains isolated from lake water, flamingo feces, microbial mats, modern stromatolites (the only one on Earth located above 4000 m!) soil and sediments from 15 different lakes. Most of the actinobacterial strains were assigned to the following genera: Streptomyces, Brachybacterium, Dietzia, Kocuria, Micrococcus, Agrococcus, Citrococcus, Nocardia, Microbacterium, Arthrobacter, Nesterenkonia, Brevibacterium and Rhodococcus. Most of these strains could be considered poly-extremophiles as they displayed resistant towards UV-B, arsenic, salt and antibiotics. These strains were tested for citotoxicity activity against other HAAL strains, and also against collection strains: Mycobacterium smegmatis, Escherichia coli, Enteroccocus faecalis, Sacharomyces cerevisae, Candida albicans, Microccocus luteus and Staphyloccocus aureus. All strains tested revealed bioactivity against at least one of the model strains. Also a metagenomic approach by 454 pyrosequencing of the recently discovered extreme stromatolites of the HAAL revealed that Actinobacteria are an important component of these special ecosystems. We could detect members of the Classes Actinobacteria, Acidimicrobidiia and Nitriliruptoria, being Nitriliruptor the most abundant representative. Based in the evidence herein presented, we proposed that the HAAL are interesting environments to mine the biotechnological potential of these extreme actinobacteria, which is yet unknown. Keywords. High-Altitude Andean Lakes, Extremophiles, actinobacteria, stromatolites.