For the purpose to clarify the reason of a characteristic phenomenon in the growth-OMP curve(reported previously), inoculum size of Leuconostoc mesenteroides and incubation period for the growth of the bacteria in the presence of various concentration of OMP were studied. It was observed that heavier inoculum size showed the refractions at higher concentration of OMP. The double refractions were observed after incubation for more than 68 hours even if absence of D-alanine in the medium, while after 24 hours incubation with DL-alanine. When higher concentration of OMP added to the medium, the bacterial growth was inhibited more in the early stage of incubation. However, the growth was stimulated more in the later stage of incubation with higher concentration of OMP between those concentrations at the first and the second refractions. It was presumed from the above result that OMP might be transferred to some unknown substance which could substitute vitamin B_6 function in the condition, in which stimulation of the bacterial growth was occured.