Purification and enzymatic properties of a neutral metalloprotease produced from the cold-adapted Vibrio species Pr21 isolated from deep seawater in Sagami Bay

Abstract

To identify new biopolymer-degrading enzymes produced from cold-adapted microorganisms, we searched for such enzymes in bag filters used for the purification of deep seawater pumped up in Sagami Bay, Japan. We isolated a casein- and azocoll-degrading cold-adapted bacterium, and it was identified as Vibrio species Pr21. The bacterium grew between 0 and 25 °C, optimally at 20–22 °C. An extracellular 36-kDa protease, which we named PR protease, was purified from the bacterial medium. PR protease is a neutral metalloprotease that degrades azocoll (optimum temperature 40 °C). When bovine skin type I collagen (acid soluble) was used as a substrate, β chains and larger multimers decreased and α1 and α2 chains accumulated with PR protease at 10, 20, and 30 °C. This indicates that PR protease cleaves telopeptide regions of collagen molecules. PR protease accelerated the liquefaction of live moon jellyfishes Aurelia aurita at 10 and 25 °C. The present findings suggest that the bag filters used in deep seawater-pumping plants are useful for the isolation of cold-adapted microorganisms, and that PR protease has potential for applications in food processing and wastewater treatment.