title: Demonstration of antifreeze protein activity in Antarctic lake bacteria.
abstract: Antifreeze proteins (AFPs) are a structurally diverse group of proteins that have the ability to modify ice crystal structure and inhibit recrystallization of ice. AFPs are well characterized in fish and insects, but very few bacterial species have been shown to have AFP activity to date. Thirty eight freshwater to hypersaline lakes in the Vestfold Hills and Larsemann Hills of Eastern Antarctica were sampled for AFPs during 2000. Eight hundred and sixty six bacterial isolates were cultivated. A novel AFP assay, designed for high-throughput analysis in Antarctica, demonstrated putative activity in 187 of the cultures. Subsequent analysis of the putative positive isolates showed 19 isolates with significant recrystallization inhibition (RI) activity. The 19 RI active isolates were characterized using ARDRA (amplified rDNA restriction analysis) and 16S rDNA sequencing. They belong to genera from the alpha- and gamma-Proteobacteria, with genera from the gamma-subdivision being predominant. The 19 AFP-active isolates were isolated from four physico-chemically diverse lakes. Ace Lake and Oval Lake were both meromictic with correspondingly characteristic chemically stratified water columns. Pendant Lake was a saline holomictic lake with different chemical properties to the two meromictic lakes. Triple Lake was a hypersaline lake rich in dissolved organic carbon and inorganic nutrients. The environments from which the AFP-active isolates were isolated are remarkably diverse. It will be of interest, therefore, to elucidate the evolutionary forces that have led to the acquisition of functional AFP activity in microbes of the Vestfold Hills lakes and to discover the role the antifreezes play in these organisms.
authors.affiliation: School of Life and Environmental Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.|Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK.
authors.forename: Jack A
authors.initials: JA
authors.lastname: Gilbert
authors.affiliation: Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Hill
authors.affiliation: Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK.
authors.forename: Christine E R
authors.initials: CER
authors.lastname: Dodd
authors.affiliation: School of Life and Environmental Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Johanna
authors.initials: J
authors.lastname: Laybourn-Parry
mesh_terms: D000864:Antarctic Regions; D021301:Antifreeze Proteins / Q000235:genetics / Q000378:metabolism*; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D005618:Fresh Water / Q000382:microbiology; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D014871:Water Microbiology
chemical_list: D021301:Antifreeze Proteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal