Open AccessEffect of exogenous extracellular polysaccharides on the desiccation and freezing tolerance of rock‐inhabiting phototrophic microorganisms
Author(s) -
Knowles Emily J.,
Castenholz Richard W.
Publication year - 2008
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2008.00568.x
Subject(s) - desiccation , biology , desiccation tolerance , phototroph , biofilm , microorganism , extracellular , extracellular polymeric substance , botany , extracellular polysaccharide , polysaccharide , chlorella , ecology , vital stain , bacteria , algae , photosynthesis , microbiology and biotechnology , staining , biochemistry , genetics
Two major stresses that threaten rock‐inhabiting microbial communities are desiccation and freezing; both result in a loss of liquid water in the cells. The mechanisms necessary to tolerate these extremes may be similar, but are not well understood. In both cases extracellular polysaccharides (EPS) seem to play an important role. This study examines whether the EPS released by a rock‐inhabiting phototroph can have a protective effect on other members of similar and neighboring microbial communities. This interaction was modeled by adding EPS isolated from the cryptoendolithic cyanobacterium Nostoc sp. to cells of the cryptoendolithic green alga Chlorella sp. and to cells of the epilithic cyanobacterium Chroococcidiopsis sp. The cells were then subjected to desiccation and freezing and the survival rates were determined by vital staining, using membrane integrity as a measure of viability. The results clearly demonstrate the importance of exogenous EPS in the desiccation tolerance of both species, while mixed results were found for the freezing trials.