Project description:Several microorganisms have wide temperature growth range and versatility to tolerate large thermal fluctuations in diverse environments. To better understand thermal adaptation of psychrotrophs, Exiguobacterium sibiricum strain 255-15 was used, a psychrotrophic bacterium that grows from -5°C to 39°C. Its genome is approximately 3 Mb in size, has a GC content of 47.7% and includes 2,978 putative protein-encoding genes (CDS). The genome and transcriptome analysis along with the organism's known physiology was used to better understand its thermal adaptation. A total of about 27%, 3.2% and 5.2% of E. sibiricum strain 255-15 CDS spotted on the DNA microarray yielded differentially expressed genes in cells grown at -2.5°C, 10°C and 39°C, respectively, when compared to cells grown at 28°C. The hypothetical and unknown genes represented 10.6%, 0.89% and 2.3% of the CDS differentially expressed when grown at -2.5°C, 10°C and 39°C versus 28°C. The transcriptome analyses showed that E. sibiricum is constitutively adapted to cold temperatures since little differential gene expression was observed at growth temperatures of 10°C and 28°C, but at the extremities of its Arrhenius growth profile, namely -2.5°C and 39°C, much more differential gene expression occurred. The genes that responded were more typically associated with stress response. Keywords: stress response to cold and hot temperatures
Project description:The aim of the work was to carry out the physiological, biochemical and genetic characterization of the Exiguobacterium alkaliphilum B-3531D strain. This strain is promising for use in the field of environmental biotechnology, since it has a pronounced ability to utilize crude oil and individual hydrocarbons in a wide temperature range. The genome of the strain was sequenced and completely assembled, it consists of a 2,903,369 bp circular chromosome and two circular plasmids, namely, pE73 (73,590 bp) and pE52 (52,125 bp). When cultivated in a mineral medium containing 2% of crude oil, the strain utilized 50% within 30 days of the experiment. In simulated seawater with the same oil content, the loss of hydrocarbons was 45% over the same period. For the first time we observed in an E. alkaliphilum strain the ability to efficiently utilize crude oil, including with an increased content of sodium chloride in the cultivation medium.