Translations:Bifidobacterium/7/en
Response to oxygen
The sensitivity of members of the genus Bifidobacterium to O2 generally limits probiotic activity to anaerobic habitats. Recent research has reported that some Bifidobacterium strains exhibit various types of oxic growth. Low concentrations of O2 and CO2 can have a stimulatory effect on the growth of these Bifidobacterium strains. Based on the growth profiles under different O2 concentrations, the Bifidobacterium species were classified into four classes: O2-hypersensitive, O2-sensitive, O2-tolerant, and microaerophilic. The primary factor responsible for aerobic growth inhibition is proposed to be the production of hydrogen peroxide (H2O2) in the growth medium. A H2O2-forming NADH oxidase was purified from O2-sensitive Bifidobacterium bifidum and was identified as a b-type dihydroorotate dehydrogenase. The kinetic parameters suggested that the enzyme could be involved in H2O2 production in highly aerated environments.