Cryoprotective Effect and Partial Characterization of a Novel Exopolysaccharide (P-ArcPo 20) Produced by Pseudoalteromonas tetraodonis Strain ArcPo 20

Abstract

Marine samples obtained from the Chukchi Sea, Arctic Ocean yielded 22 bacterial strains that secrete polysaccharides. Of those, seven strains produced cryoprotective exopolysaccharides (EPS). The strain ArcPo 20, identified as Pseudoalteromonas tetraodonis by 16S rDNA analysis, demonstrated the highest cryoprotective effect and was selected for the further study. The EPS, P-ArcPo 20, was purified by protease treatment and gel filtration chromatography. EPS characterization was confirmed by the gel permeation chromatography, gas chromatography-mass spectrometry, and Fourier transform infrared spectroscopy analysis. The P-ArcPo 20 cryoprotective activity was characterized using an E. coli viability test. In the presence of 0.5% (w/v) EPS, the E. coli cell survival ratio was 91.22 ± 4.21% over five freeze-thaw cycles. These biochemical characteristics suggest that the EPS P-ArcPo 20 may be useful in cryoprotectant development for biotechnological and medical applications.