시판식품에서 분리된 단백분해성이 강한 Streptococcus sp.의 특성

Characterization of Proteolytic Streptococcus sp. Isolated from Market Foods

본 연구는 단백질 분해성이 강한 세균을 분리하고 그 균의 특성과 균이 생성하는 효소의 성질을 알기 위하여 시판식품 즉 ground beef, cooked shrimp meat, perch fillet, oyster meat, beef with textured vegetable protein, fish digest 등에서 세균을 분리하였다. 분리된 740균주중에서 $30.8\%$에 해당하는 228균주가 단백질 분해성이 있었으며 이 중에서 단백질 분해성이 제일 강한 균주는 Streptococcus sp.였다. 본 균주는 배지에 $KH_{2}PO_4\;0.15\%,\;K_{2}HPO_4\;0.4\%$를 첨가하여 $37^{\circ}C$에서 6시간 배양했을 때 maximum growth에 도달하였고 균체외 단백질 분해효소의 활성은 배양 7시간경에 최고에 달하였다. 그리고 본 Streptococcus sp.가 생성한 균체외 단백분해효소는 EDTA나 o-phenanthroline에 강한 조해작용을 받고 phenylmethylsulfonylfluoride나 p-hydroxymercuribenzoate에 영향을 받지 않는 metal-chelator sensitive protease임을 알 수 있었다.

The proteolytic bacteria were isolated from the market foods such as ground beef, cooked shrimp meat, perch fillet, oyster meat, beef with textured vegetable protein and fish digest distributed at supermarket in Corvallis, Oregon, U.S.A. Two hundred and twenty-eight strains($30.8\%$) have proteolytic activity from 740 strains isolated from the examined samples and the strongest proteolytic strain among them was identified as a Streptococcus sp. Its maximum growth was showed at about 6 hours culture at $37^{\circ}C$ with shaking incubator in the medium added $0.15\%$ potassium phosphate monobasic and $0.4\%$ potassium phosphate dibasic, while the strongest activity of its extracellular protease was observed after 7 hours culture. The exoenzyme produced by the Streptococcus sp. was observed as a metal chelator sensitive protease, which are strongly inhibited by EDTA and o-phenanthroline but not affected by phenylmethylsulfonylfluoride and p-hydroxymercuribenzoate.