Micrococcus antibiotic to Bac. Coli and Staphyllococcus found in horse feces

A microccoccus which is antibiotic to Bac. Coli was isoland from horse feces. From the test by the continuative dilution method or the cup method the micrococcus seemedto show the highest antibiotic action toBac. Coli in 3 days and to Staphyllococces in 6-9 days when cultured in Bouillon. The critical dilution which showed the antibiotic action was 1 ： 10240-20480 for Bac. Coli and 1 : 2560 for Staphyllococcus. The antibiotic action of the micrococcus was grcater than that of Penicilline. Itseems to be also antibiotic to other Gram-negative bacilli, for example the bacteria of Sarmonella group, and the action shall be later investigated.