FIG 5.

Correlation of proteolytic activity and antagonistic activity. (a and b) Proteolytic activity was detected using skim milk agar plates (a), while antagonistic activity was tested using strain LN121 indicator plates made by mixing the cells of strain LN121 with solid medium and pouring the mixture into the petri dishes (b). Supernatants of strain EPS under stationary phase were collected for activity tests. Phenylmethylsulfonyl fluoride (PMSF), an inhibitor of serine protease, was used to eliminate the proteolytic activities. The concentration of PMSF in the supernatants was 10 mM or 20 mM, while supernatants without PMSF and liquid AS-168 medium supplemented with PMSF (20 mM) were used as controls. LN121, Haloarcula sp. LN121; medium, liquid AS-168 medium.