Characterization of amylase produced by cold-adapted bacteria from Antarctic samples

The Antarctic continent is characterized by extreme conditions and encompasses peculiar environments which represent promising habitats for the recovery of well-adapted microorganisms with unique metabolic capabilities. Enzymatic activity combined to salinity and pH tolerance of bacteria that thrive in low temperature environment have attracted attention of researchers in recent years and, as scarce information on that topic is available, the aim of this study was to prospect bacteria isolated from Antarctic samples for extracellular amylase activity and to determine their salinity and pH tolerances. Ninety-one bacteria isolated from Antarctic environmental samples, including marine sponges and invertebrates, sediments and soil biofilm, were screened. Fourty-two isolates were selected as putative amylase producers based on their ability to produce clearing zones in agar plates. Eighty-six and forty-four isolates were able to grow at 5 and 10% NaCl concentrations, respectively. The best enzymatic activities for isolates 226 and 227 were 768.5 U dL 1 (20 degrees C) and 1410,16 U dL 1 (20 degrees C), respectively, both influenced by the temperature. All variables assayed showed statistically significant differences for isolates 227 and 226, demonstrating that enzyme activities respond differently to the applied conditions. This is the first report that describes the amylase activity from Carnobacterium and Psychrobacter strains isolated from Antarctic samples. These results encourage subsequent investigations of enzymes produced by microorganisms adapted to low temperatures and high osmolarity conditions, aiming future biotechnological application in pharmaceutical, textile or food industries.