IDENTIFICATION AND ANALYSIS OF BACTERIA ISOLATED FROM EL SALAR DEL HOMBRE MUERTO

MARTÍNEZ FABIANA; ORCE INGRID GEORGINA; RAJAL VERÓNICA; IRAZUSTA VERÓNICA

Tucumán

Congreso; XII Congreso Argentino de Microbiología General-Samige; 2017

Saline environments harbor microorganisms adapted to extreme conditions. These organisms possess some properties and share some features that allow them to live in such hostile environment. In previous assays, several microorganisms were isolated from El Salar del Hombre Muerto, a salt flat area in the northwest of Argentina, where mainly lithium is extracted. Their characterization allowed us to establish the presence of a wide diversity according to their macro and micromorphology. They were able to grow using different carbon and nitrogen sources. Quantitative and qualitative assays to establish the tolerance against lithium were carried out. Five bacterial strains were selected as the most tolerant for further studies; among them there were cocci and bacilli, Gram positive and negative, non-pigmented and pigmented cells and some of them biofilm forming organisms.In this work, the microbial identities of five strains (SA211, FAMB1, SX139, HA120A and SFS) isolated from El Salar del Hombre Muerto were studied and the phylogenetic closeness within themselves and with strains from the NCBI database was determined.In order to know the proteins involved in lithium tolerance a proteomic study was conducted. Selected microorganisms were grown in a defined culture media with two different concentrations of lithium chloride. Analyzing the crude cell extracts by mono-dimensional polyacrylamide gel electrophoresis, a differential protein profile was observed among cells grown at 10 and 30 g/L of LiCl. Those proteins would be involved in the ability of these bacteria to survive and grow in adverse conditions. Microorganisms were also identified by sequencing the 16S rRNA gene for which first we extracted the nucleic acids and then amplified through PCR with universal primers. Identity estimation of these five microorganisms was performed by comparison with sequences from the NCBI (National Center for Biotechnology Information) database and the phylogenetic tree was constructed using MEGA software. Three of these strains were classified within the gender Bacillus (HA120A, SX139 and FAMB1), SA211 was closely related to Micrococcus genderandSFS belonged to the gender Halomonas. The analysis of the sequences let us conclude that although sharing the ability to tolerate high concentrations of lithium chloride, the selected strains possess a wide variety of different properties and identities, even though most of them belong to the Bacillus gender. In a bacterial community,variety is one of the most important features, because it allows adaptation to environmental shifts, for example, anthropogenic contamination. Interestingly it is known that the Halomonas gender harbor alkalitolerant microorganisms, some strains from the gender Bacillus have the ability to produce exopolymers and some strains from the Kocuria gender degrade hydrocarbons, just an example. Further studies are needed to elucidate the capabilities of these strains.