Isolation and Characterization of Moderately Halophilic and Halotolerant Bacteria from the Freshwater Al-Asfar Lake, Al Ahsa, Saudi Arabia

摘要

A range of water samples from the Al-Asfar lake, Al Ahsa, Saudi Arabia were enriched with LB medium (plates and liquid medium) containing a range of salt concentrations up to 2 M NaCl. Three strains of halotolerant or moderately halophilic bacteria were isolated and identified by 16S rDNA sequencing as belonging to the genera Staphylococcus, Halobacillus and Halomonas. The first two organisms (S. warneri and Halobacillus sp.) were further charcaterized to understand their ability to grow at high salinities up to 3 M NaCl. Halobacillus sp. was shown to be moderately halophilic (optimum growth between 0.17 and 1 M NaCl), whereas S. warneri was shown to be halotolerant, optimum growth at 0.17 M NaCl. Nuclear magnetic resonance (NMR) was used to determine the compatible solutes accumulated by the two strains. Betaine was accumulated by both organisms and Halobacillus sp. also utilized glutamate at low salt concentrations. This work demonstrates the presence of moderately halophilic and halotolerant bacteria in a freshwater lake.