This report describes the isolation and characterization of bacterial isolates that produce anti−microbial compounds from one of the South Shetland Islands, King George Is − land, Antarctica. Of a total 2465 bacterial isolates recovered from the soil samples, six (BG5, MTC3, WEK1, WEA1, MA2 and CG21) demonstrated inhibitory effects on the growth of one or more Gram−negative or Gram−positive indicator foodborne pathogens ( i.e. Escherichia coli 0157:H7, Salmonella spp., Klebsiella pneumoniae , Enterobacter cloacae , Vibrio parahaemolyticus and Bacillus cereus ). Upon examination of their 16S rRNA sequences and biochemical profiles, the six Antarctic bacterial isolates were identified as Gram−negative Pedobacter cryoconitis (BG5), Pseudomonas migulae (WEK1), P. corrugata (WEA1) and Pseudomonas spp. (MTC3, MA2, and CG21). While inhibitors produced by strains BG5, MTC3 and CG21 were sensitive to protease treatment, those produced by strains WEK1, WEA1, and MA2 were insensitive to catalase, lipase, a −amylase, and protease enzymes. In addtion, the six Antarctic bacterial isolates appeared to be resistant to multiple antibiotics.

A filamentous benthic cyanobacteria, strain USMAC16, was isolated from the High Arctic Svalbard archipelago, Norway, and a combination of morphological, ultrastructural and molecular characterisation (16S rRNA gene sequence) used to identify to species level. Cell dimensions, thylakoid arrangement and apical cell shape are consistent with the Pseudanabaena genus description. The molecular characterisation of P. catenata gave 100% similarity with Pseudanabaena catenata SAG 1464-1, originally reported from Germany. Strain USMAC16 was cultured under a range of temperature and photoperiod conditions, in solid and liquid media, and harvested at exponential phase to examine its phenotypic plasticity. Under different culture conditions, we observed considerable variations in cell dimensions. The longest cell (5.91±0.13 μm) was observed at 15°C under 12:12 light:dark, and the widest cell (3.24±0.06 μm) at 4°C under 12:12 light: dark in liquid media. The study provides baseline data documenting the morphological variation of P. catenata in response to changing temperature regimes.