The microorganisms and complex culture media used in this
study are shown in Table 1. Microorganisms were kept frozen at
80 C in broth containing glycerol (15%, v/v). Before the test, stock
cultures were inoculated into the broth and incubated at 37 C for
24 h. Cultures were transferred to the broth three times at 24 h
intervals. All media were obtained from Difco Co.