对双歧杆菌DM9227株的实验研究 Ⅲ.双歧杆菌DM9227株与蜡样芽胞杆菌DM423株共生关系的初步研究

本文对厌氧的双歧杆菌DM9227株与需氧的蜡样芽胞杆菌DM423株的共生关系进行了初步研究。将DM9227株与DM423株分别单独及按一定比例等量混合接种于BS肉汤内进行培养,间隔一定时间检测两菌在培养基内菌数的消长情况。结果表明DM423株与DM9227株之间呈偏生关系,即DM423株对DM9227株有促进作用,且在两菌比例适宜(1:100)情况下促进作用更明显,而DM9227株对DM423株有抑制作用。进一步将接种DM423株的Nb琼脂平板与接种DM9227株的BS琼脂平板在普通环境下一起密闭培养,可见厌氧的DM9227株生长良好,提示DM423株可能是通过消耗氧气,降低培养基的Eh,从而促进DM9227株生长的。

THE PRELIMINARY RESEARCH ON THE SYMBIOSIS BETWEEN BIFIDOBACTERIUM DM9227 STRAIN AND BACILLUS CEREUS DM423 STRAIN

This study investigated the symbiosis between Bifidobacterium DM9227 strain (Bif.DM9227) and Bacillus cereus DM423 strain (Bac.DM423).According to the turbidity of these two organism cultures at log growth stage, Bac.DM423 BS culture was mixed with that of Bif.DM9227 pro- portionally in BS culture medium.During normal incubation, quantities of each species in the mixed culture was examined at intervals.Asa result, when Bac.DM423 was in proportion of 1:100 to Bif.DM9227, the amounts of Bif.DM9227 in mixed culture were significantly higher than that of its pure culture.On the other hand, the amounts of Bac.DM423 were lower than that of its pure culture.These results showed that Bac.DM423 had definite promoting effect on Bif.DM9227, Bif.DM9227 could inhibit the growth ofBac.DM423.Further research demonstrated that the mechanism ofthe promoting effect may be resulted from the reduction of O_2 and Eh in the mixed culture by Bac.DM423.The inhibiting action may be resulted from the organic acids produced by Bif.DM9227, which lowered the pH value of the culture medium against the growth of Bac.DM423.