Screening and Identification of A Strain with High Protease in Fermentation of Tuna Dark Meat

WU Li-na;ZHAO Xiao-hui;GUO Kai-qing;YANG Yu-jie;FANG Xu-bo;CHEN Xiao-e;ZHANG Yin-zhao;College of Food and Medicine, Zhejiang Ocean University;State Key Laboratory of Aquatic Products Processing of Zhejiang Province;Zhejiang Fengyu Biological Products Limited Company;

Tuna dark meat;;transparent circle method;;Forint phenol reagent method;;isolation;;identification;;growth conditions

Using Three strains of bacteria secreting extracellular protease were isolated from soil of Baishan in Zhoushan by transparent circle method, the bacterium with highest protease activity was identified and the most suitable growth conditions was studied. The collected samples were screened by transparent circle method to get three pure strains whose protease activity would be measured by Forint phenol reagent method. The strain with the highest protease activity was identified by the16 S r RNA sequence analysis and the phylogenetic tree was constructed by MEGA software. The inoculation amount,temperature,time and pH had been analyzed on the influence of its protease activity. The results showed that the study demonstrates that the zjoub-1 strain with highest protease activity was defined as bacillus subtilis. The optimal condition for fermentation of Tuna dark meat was as follows: the inoculation quantity was 2%,the incubation temperature was 37 ℃, the incubation time was about 48 h, the initial pH was 7.4. Under this circumstance, the strain has the highest protease activity, which illustrates that the strain with high protease activity can degrade the Tuna dark meat efficiently.