Effects of incubation temperature on growth and production of exopolysaccharides by an Antarctic sea ice bacterium grown in batch culture

Type Article
Date 2005-07
Language English
Author(s) Nichols Carol1, Bowman John2, Guezennec Jean3
Affiliation(s) 1 : Univ Tasmania, Sch Agr Sci, Hobart, Tas 7000, Australia.
2 : Univ Tasmania, Australian Food Safety Ctr Excellence, Hobart, Tas, Australia.
3 : Inst Francais Rech Exploitat Mer, Ctr Brest, DRV VP, F-29280 Plouzane, France.
Source Applied and environmental microbiology (0099-2240) (American society for microbiology), 2005-07 , Vol. 71 , N. 7 , P. 3519-3523
DOI 10.1128/AEM.71.7.3519-3523.2005
WOS© Times Cited 61
Keyword(s) EPS yield, Psychrotolerant, Sea ice, Marine bacteria, Antarctica, Exopolymer, Exopolysaccharides
Abstract The sea ice microbial community plays a key role in the productivity of the Southern Ocean. Exopolysaccharide (EPS) is a major component of the exopolymer secreted by many marine bacteria to enhance survival and is abundant in sea ice brine channels, but little is known about its function there. This study investigated the effects of temperature on EPS production in batch culture by CAM025, a marine bacterium isolated from sea ice sampled from the Southern Ocean. Previous studies have shown that CAM025 is a member of the genus Pseudoalteromonas and therefore belongs to a group found to be abundant in sea ice by culture-dependent and -independent techniques. Batch cultures were grown at -2 degrees C, 10 degrees C, and 20 degrees C, and cell number, optical density, pH, glucose concentration, and viscosity were monitored. The yield of EPS at -2 degrees C and 10 degrees C was 30 times higher than at 20 degrees C, which is the optimum growth temperature for many psychrotolerant strains. EPS may have a cryoprotective role in brine channels of sea ice, where extremes of high salinity and low temperature impose pressures on microbial growth and survival. The EPS produced at -2 degrees C and 10 degrees C had a higher uronic acid content than that produced at 20 degrees C. The availability of iron as a trace metal is of critical importance in the Southern Ocean, where it is known to limit primary production. EPS from strain CAM025 is polyanionic and may bind dissolved cations such at trace metals, and therefore the presence of bacterial EPS in the Antarctic marine environment may have important ecological implications.
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