Enrichment of cold-active protease-producing bacteria from Arctic terrestrial and marine samples

Abstract

Protease-producing bacterial strains were isolated by enrichment in 0.1X NA or ZoBell semi-solid agar medium supplemented with pork pieces at 4&#61616

C for 6 months. Thirty eight and 51 strains were isolated from Arctic terrestrial and marine samples, respectively. Optimal temperature for growth ranged between 4&#61616

C and 30&#61616

C depending on the strains. Protease secretion was observed in 48 strains, forming hydrolytic zone on solid media supplemented with skim milk. They were included in Pseudoalteromonas (33 strains), Pseudomonas (10 strains), Arthrobacter (4 strains), and Flavobacterium (1 strain). Protease secretion was higher at 4&#61616

C than at 20&#61616

C in most strains. From these results, it is concluded that bacterial strains producing cold-active protease could be effectively enriched by long-term incubation at 4&#61616

C in semi-solid agar medium.