title: Production of cryoprotectant extracellular polysaccharide substances (EPS) by the marine psychrophilic bacterium Colwellia psychrerythraea strain 34H under extreme conditions.
abstract: Extracellular polysaccharide substances (EPS) play critical roles in microbial ecology, including the colonization of extreme environments in the ocean, from sea ice to the deep sea. After first developing a sugar-free growth medium, we examined the relative effects of temperature, pressure, and salinity on EPS production (on a per cell basis) by the obligately marine and psychrophilic gamma-proteobacterium, Colwellia psychrerythraea strain 34H. Over growth-permissive temperatures of approximately 10 to -4 degrees C, EPS production did not change, but from -8 to -14 degrees C when samples froze, EPS production rose dramatically. Similarly, at growth-permissive hydrostatic pressures of 1-200 atm (1 atm = 101.325 kPa) (at -1 and 8 degrees C), EPS production was unchanged, but at higher pressures of 400 and 600 atm EPS production rose markedly. In salinity tests at 10-100 parts per million (and -1 and 5 degrees C), EPS production increased at the freshest salinity tested. Extreme environmental conditions thus appear to stimulate EPS production by this strain. Furthermore, strain 34H recovered best from deep-freezing to -80 degrees C (not found for Earthly environments) if first supplemented with a preparation of its own EPS, rather than other cryoprotectants like glycerol, suggesting EPS production as both a survival strategy and source of compounds with potentially novel properties for biotechnological and other applications.
authors.affiliation: School of Oceanography, University of Washington, Seattle, WA98195, USA.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Marx
authors.forename: Shelly D
authors.initials: SD
authors.lastname: Carpenter
authors.forename: Jody W
authors.initials: JW
authors.lastname: Deming
mesh_terms: D003080:Cold Temperature; D003451:Cryoprotective Agents / Q000378:metabolism*; D003470:Culture Media; D005615:Freezing; D020563:Gammaproteobacteria / Q000378:metabolism*; D006874:Hydrostatic Pressure; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D054712:Salinity; D014871:Water Microbiology
chemical_list: D003451:Cryoprotective Agents; D003470:Culture Media; D011135:Polysaccharides, Bacterial