Molecular and phenetic characterization of the bacterial assemblage of Basque Lake, BC, an environment with high concentrations of magnesium sulphate, and its relevance to mars

Abstract

Halotolerant bacteria favor environments containing high concentrations of salts. While there are a multitude of hypersaline environments containing various salts on Earth, those heavily dominated with sodium chloride (NaCl) have been of academic rigor. This thesis pertains to environments with high concentrations of magnesium sulphate (MgSO4), which presents ample opportunity for discovery. Basque Lake, BC is one such environment that is dominated by magnesium sulphate. Basque Lake is an ephemeral lake containing near-saturated levels of magnesium sulphate that precipitates as epsomite (MgSO4?7H2O). Natural environments containing high concentrations of magnesium sulphate are rare and previous microbiological effort is limited. For a microbe to persist in Basque Lake it must withstand extreme conditions similar to those present on the Martian surface including salinity, aridity, and temperature. Any microbe isolated from Basque Lake could give astrobiologists key details on what traits a Martian life-form may have and to limit potential forward contamination. Approximately 65 bacterial isolates were obtained through repetitive streak-plating in high salt media. The bacterial isolates were characterized phenotypically and subjected to 16S rRNA sequencing and phylogenetic analyses. Gram-positive bacteria dominated the culture collection including members of Virgibacillus, Marinococcus, and Staphylococcus. Members of the Gram-negative genera Halomonas and Salinivibrio were represented in the culture collection as well. Results indicate that microbes isolated from epsom-rich environments such as Basque Lake present a potential risk of forward contamination. This research was supported by NASA ROSES Planetary Protection (PPR), KANSAS NASA EPSCoR, and KINBRE.