Cold-adaptation mechanism of psychrotrophic bacteria and their applications

Abstract

We studied cold-adaptation mechanisms of a psychrotroph, Shewanella livingstonensis Ac10, isolated from Antarctic seawater. We found that eicosapentaenoic acid (EPA) occurring in phospholipids is important for the growth at low temperatures by disrupting the genes essential for EPA synthesis. On the other hand, we carried out proteomic analysis of the soluble and membrane proteins of this bacterium grown at 4°C and 18°C and found that the amounts of 51 proteins were increased at 4°C (> 2-fold). We identified 28 of them by peptide mass fingerprinting. Disruption of the gene coding for one of these proteins, a homolog of OmpC, caused a growth defect at low temperatures, suggesting its role in cold-adaptation. Since S. livingstonensis Ac10 grows well at low temperatures, it is expected to be useful as the host for the production of thermolabile heterologous proteins. We constructed expression vectors for this psychrotroph and demonstrated their usefulness.