Enrichment of arsenic transforming and resistant heterotrophic bacteria from sediments of two salt lakes in Northern Chile

• Published in: Extremophiles : life under extreme conditions 2012-05, Vol.16 (3), p.523-538
• Main Authors: Lara, José, Escudero González, Lorena, Ferrero, Marcela, Chong Díaz, Guillermo, Pedrós-Alió, Carlos, Demergasso, Cecilia
• Format: Article
• Language: English
• Subjects: Acetic acid; Anaerobiosis - physiology; Animal, plant and microbial ecology; Arsenic; Arsenic - metabolism; Bacteria; Biochemistry; Biodegradation, Environmental; Biogeochemical cycles; Biogeochemistry; Biological and medical sciences; Biomedical and Life Sciences; Biotechnology; Chile; Community structure; Ecotypes; Energy conservation; Firmicutes; Freshwater; Fundamental and applied biological sciences. Psychology; Hydrogen sulfide; Lakes; Lakes - microbiology; Life Sciences; Metabolism; Microbial activity; Microbial Ecology; Microbiology; Microorganisms; Nucleic acids; Original Paper; Proteobacteria; Proteobacteria - growth & development; Proteobacteria - isolation & purification; Proteobacteria - metabolism; Saline water; Salt lakes; Sediment samplers; Sodium chloride; Various environments (extraatmospheric space, air, water); Water Microbiology
• ISSN: 1431-0651; 1433-4909
• DOI: 10.1007/s00792-012-0452-1

Microbial populations are involved in the arsenic biogeochemical cycle in catalyzing arsenic transformations and playing indirect roles. To investigate which ecotypes among the diverse microbial communities could have a role in cycling arsenic in salt lakes in Northern Chile and to obtain clues to facilitate their isolation in pure culture, sediment samples from Salar de Ascotán and Salar de Atacama were cultured in diluted LB medium amended with NaCl and arsenic, at different incubation conditions. The samples and the cultures were analyzed by nucleic acid extraction, fingerprinting analysis, and sequencing. Microbial reduction of As was evidenced in all the enrichments carried out in anaerobiosis. The results revealed that the incubation factors were more important for determining the microbial community structure than arsenic species and concentrations. The predominant microorganisms in enrichments from both sediments belonged to the Firmicutes and Proteobacteria phyla, but most of the bacterial ecotypes were confined to only one system. The occurrence of an active arsenic biogeochemical cycle was suggested in the system with the highest arsenic content that included populations compatible with microorganisms able to transform arsenic for energy conservation, accumulate arsenic, produce H 2 , H 2 S and acetic acid (potential sources of electrons for arsenic reduction) and tolerate high arsenic levels.