Extracellular hydrolytic enzyme production by proteolytic bacteria from the Antarctic

Cold−adapted marine bacteria producing extracellularhydrolytic enzymes are important for their industrial application and play a key role in degradation of particulate organic matterin their natural environment. In this work, members of a previously−obtained protease−producing bacterial collection isolated from different marine sources from Potter Cove(King George Island, South Shetlands) were taxonomically identified and screened for their ability to produce other economically relevant enzymes. Eighty−eight proteolytic bacterial isolates were grouped into 25 phylotypesbased on their Amplified Ribosomal DNA Restriction Analysisprofiles. The sequencing of the 16S rRNA genes from representative isolates of the phylotypesshowed that the predominant culturable protease−producing bacteria belonged to the class Gammaproteobacteriaand were affiliated to the genera Pseudomonas, Shewanella, Colwellia, and Pseudoalteromonas, the latter being the predominant group (64% of isolates). In addition, members of the classes Actinobacteria, Bacilli and Flavobacteria were found. Among the 88 isolates screened we detected producers of amylases (21), pectinases(67), cellulases (53), CM−cellulases (68), xylanases(55) and agarases(57). More than 85% of the isolates showed at least one of the extracellularenzymatic activities tested, with some of them producing up to six extracellularenzymes. Our results confirmed that using selective conditions to isolate producers of one extracellularenzyme activity increases the probability of recovering bacteria that will also produce additional extracellularenzymes. This finding establishes a starting point for future programs oriented to the prospecting for biomolecules in Antarctica.