title: Properties of a novel extracellular cell-free ice nuclei from ice-nucleating Pseudomonas antarctica IN-74.
abstract: Some ice-nucleating bacterial strains, including Pantoea ananatis (Erwinia uredovora), Pseudomonas fluorescens, and Pseudomonas syringae isolates, were examined for the ability to shed ice nuclei into the growth medium. A novel ice-nucleating bacterium, Pseudomonas antarctica IN-74, was isolated from Ross Island, Antarctica. Cell-free ice nuclei from P. antarctica IN-74 were different from the conventional cell-free ice nuclei and showed a unique characterization. Cell-free ice nuclei were purified by centrifugation, filtration (0.45 microm), ultrafiltration, and gel filtration. In an ice-nucleating medium in 1 liter of cell culture, maximum growth was obtained with the production of 1.9 mg of cell-free ice nuclei. Ice nucleation activity in these cell-free ice nuclei preparations was extremely sensitive to pH. It was demonstrated that the components of cell-free ice nuclei were protein (33%), saccharide (12%), and lipid (55%), indicating that cell-free ice nuclei were lipoglycoproteins. Also, carbohydrate and lipid stains showed that cell-free ice nuclei contained both carbohydrate and lipid moieties.
authors.affiliation: Department of Biotechnology, Faculty of Engineering, Kansai University, Suita-shi, Osaka, Japan. gm0d801@ipcku.kansai-u.ac.jp
authors.forename: Naomi
authors.initials: N
authors.lastname: Muryoi
authors.forename: Hidehisa
authors.initials: H
authors.lastname: Kawahara
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Obata
mesh_terms: D000864:Antarctic Regions; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000502:physiology* / Q000648:ultrastructure; D002474:Cell-Free System / Q000737:chemistry*; D019286:Endopeptidase K / Q000378:metabolism; D005110:Extracellular Space / Q000737:chemistry; D005615:Freezing; D006023:Glycoproteins / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007053:Ice; D008074:Lipoproteins / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D008854:Microscopy, Electron; D020636:Pantoea / Q000737:chemistry; D011549:Pseudomonas / Q000737:chemistry* / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D011551:Pseudomonas fluorescens / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods; D044366:Transition Temperature; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D006023:Glycoproteins; D007053:Ice; D008074:Lipoproteins; C063113:ice nucleation protein; D010738:Type C Phospholipases; D019286:Endopeptidase K