title: Low temperature growth, freezing survival, and production of antifreeze protein by the plant growth promoting rhizobacterium Pseudomonas putida GR12-2.
abstract: The plant growth promoting rhizobacterium Pseudomonas putida GR12-2 was originally isolated from the rhizosphere of plants growing in the Canadian High Arctic. Here we report that this bacterium was able to grow and promote root elongation of both spring and winter canola at 5 degrees C, a temperature at which only a relatively small number of bacteria are able to proliferate and function. In addition, the bacterium survived exposure to freezing temperatures, i.e., -20 and -50 degrees C. In an effort to determine the mechanistic basis for this behaviour, it was discovered that following growth at 5 degrees C, P. putida GR12-2 synthesized and secreted to the growth medium a protein with antifreeze activity. Analysis of the spent growth medium, following concentration by ultrafiltration, by SDS-polyacrylamide gel electrophoresis revealed the presence of one major protein with a molecular mass of approximately 32-34 kDa and a number of minor proteins. However, at this point it is not known which of these proteins contains the antifreeze activity.
authors.affiliation: Department of Biology, University of Waterloo, ON, Canada.
authors.forename: X
authors.initials: X
authors.lastname: Sun
authors.forename: M
authors.initials: M
authors.lastname: Griffith
authors.forename: J J
authors.initials: JJ
authors.lastname: Pasternak
authors.forename: B R
authors.initials: BR
authors.lastname: Glick
mesh_terms: D021301:Antifreeze Proteins; D001426:Bacterial Proteins / Q000096:biosynthesis*; D002455:Cell Division; D004591:Electrophoresis, Polyacrylamide Gel; D005615:Freezing; D006023:Glycoproteins / Q000032:analysis / Q000096:biosynthesis*; D007053:Ice; D018517:Plant Roots / Q000254:growth & development; D016958:Pseudomonas putida / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D012639:Seeds / Q000254:growth & development / Q000382:microbiology*; D013696:Temperature
chemical_list: D021301:Antifreeze Proteins; D001426:Bacterial Proteins; D006023:Glycoproteins; D007053:Ice