Psychromonas boydii sp. nov., a gas-vacuolate, psychrophilic bacterium isolated from an Arctic sea-ice core.

A gas-vacuolate bacterium, strain 174(T), was isolated from a sea-ice core collected from Point Barrow, Alaska, USA. Comparative analysis of 16S rRNA gene sequences showed that this bacterium was most closely related to Psychromonas ingrahamii 37(T), with a similarity of >99 %. However, strain 174(T) could be clearly distinguished from closely related species by DNA-DNA hybridization; relatedness values determined by two different methods between strain 174(T) and P.

Investigating molecular recognition and biological function at interfaces using piscidins, antimicrobial peptides from fish.

We studied amidated and non-amidated piscidins 1 and 3, amphipathic cationic antimicrobial peptides from fish, to characterize functional and structural similarities and differences between these peptides and better understand the structural motifs involved in biological activity and functional diversity among amidated and non-amidated isoforms. Antimicrobial and hemolytic assays were carried out to assess their potency and toxicity, respectively. Site-specific high-resolution solid-state NMR orientational restraints were obtained from (15)N-labeled amidated and non-amidated piscidins 1 and 3 in the presence of hydrated oriented lipid bilayers.

Psychromonas ingrahamii sp. nov., a novel gas vacuolate, psychrophilic bacterium isolated from Arctic polar sea ice.

A gas vacuolate bacterium, designated strain 37T, was isolated from a sea ice core collected from Point Barrow, Alaska, USA. Cells of strain 37T were large (6-14 microm in length), rod-shaped, contained gas vacuoles of two distinct morphologies, and grew well at NaCl concentrations of 1-10 % and at temperatures of -12 to 10 degrees C. The DNA G+C content was 40 mol%.

Methylosarcina lacus sp. nov., a methanotroph from Lake Washington, Seattle, USA, and emended description of the genus Methylosarcina.

An obligately methanotrophic bacterial strain, LW14T, isolated from the sediment of Lake Washington, Seattle, USA, is described taxonomically. The isolate is an aerobic, Gram-negative, non-motile bacterium capable of growth on methane, and possesses type I intracytoplasmic membranes (i.e.

Biochemical characterization of a beta-galactosidase with a low temperature optimum obtained from an Antarctic arthrobacter isolate.

A psychrophilic gram-positive isolate was obtained from Antarctic Dry Valley soil. It utilized lactose, had a rod-coccus cycle, and contained lysine as the diamino acid in its cell wall. Consistent with these physiological traits, the 16S ribosomal DNA sequence showed that it was phylogenetically related to other Arthrobacter species.

Analysis of sMMO-containing type I methanotrophs in Lake Washington sediment.

Methane-oxidizing bacteria (methanotrophs) containing soluble methane monooxygenase (sMMO) are of interest in natural environments due to the high co-metabolic activity of this enzyme with contaminants such as trichloroethylene. We have analysed sMMO-containing methanotrophs in sediment from a freshwater lake. Environmental clone banks for a gene encoding a diagnostic sMMO subunit (mmoX) were generated using DNA extracted from Lake Washington sediment and subjected to RFLP analysis.

Estimation of methanotroph abundance in a freshwater lake sediment.

The numbers of methane-oxidizing bacteria (methanotrophs) in the sediments of Lake Washington were estimated using three culture-independent methods. Quantitative slot-blot hybridizations were performed with type I and type II methanotroph-specific probes. These data were compared to data from quantitative hybridizations using a pmoA-specific probe and a eubacterial probe.