Bacterial diversity from benthic mats of Antarctic lakes as a source of new bioactive metabolites.

During the MICROMAT project, the bacterial diversity of microbial mats growing in the benthic environment of Antarctic lakes was accessed for the discovery of novel antibiotics. In all, 723 Antarctic heterotrophic bacteria belonging to novel and/or endemic taxa in the α-, β- and γ-subclasses of the Proteobacteria, the Bacteroidetes branch, and of the high and low percentage G+C Gram-positives, were isolated, cultivated in different media and at different temperatures, and then screened for the production of antimicrobial activities. A total of 6348 extracts were prepared by solid phase extraction of the culture broths or by biomass solvent extraction.

Biological denitrification in drinking water treatment using the seaweed Gracilaria verrucosa as carbon source and biofilm carrier.

Chemical and microbiological aspects were investigated with regard to biological denitrification of drinking water using the seaweed Gracilaria verrucosa as the carbon and energy substrate and as physical support for the microbial flora in semibatch, fixed-bed reactors. Complete removal of nitrate (100 mg/L) was readily achieved without accumulation of nitrite. Microbiological analysis indicated that the effluent of the reactor contained high numbers of bacteria (>10(6)/mL total count).

Reclassification of [Cytophaga] marinoflava Reichenbach 1989 as Leeuwenhoekiella marinoflava gen. nov., comb. nov. and description of Leeuwenhoekiella aequorea sp. nov.

Five heterotrophic, aerobic, halotolerant and pigmented bacterial strains with gliding motility were isolated from Antarctic sea water; one other isolate was collected from the sea urchin Strongylocentrotus intermedius in the Gulf of Peter the Great in the Sea of Japan. 16S rRNA gene sequence analysis indicated that the strains are members of the family Flavobacteriaceae, the nearest neighbour (with 97.1 % sequence similarity) being the misclassified species [Cytophaga] marinoflava.

Flavobacterium fryxellicola sp. nov. and Flavobacterium psychrolimnae sp. nov., novel psychrophilic bacteria isolated from microbial mats in Antarctic lakes.

Taxonomic studies were performed on seven strains isolated from microbial mats in Antarctic lakes of the McMurdo Dry Valleys. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these strains are related to the genus Flavobacterium; sequence similarity values with their nearest phylogenetic neighbours ranged from 97.0 to 98.