A high proportion of the probiotic microbial population is microaerophilic (requires very little oxygen for their growth) or even anaerobic (grows in absence of oxygen). Oxygen at higher concentration can be detrimental for the growth and proliferation of microorganisms. Excess of oxygen in the system will result in the formation of reactive oxygen species or high energy containing free radicals. These reactive oxygen agents can damage the membrane system and other organelles, creating ionic imbalance thereby killing the cells. In order to protect them from the damaging effects of oxygen, many bacteria possess oxygen scavenging enzymes that can neutralize the toxic effects of oxygen. However, most of the probiotic bacteria due to their origin in low oxygen content environment lack the enzymes or the basic mechanism to retaliate to such conditions. As such, the viable count of the probiotics seems to be highly compromised under packaged condition or in food products like yoghurt when exposed to oxygen. Since, the viability of the probiotics is an important issue in order for it to act effectively, methods should be devised to make them fight the menace of oxygen toxicity. Work on both natural and artificial ways of inhibiting it is in progress. [Read more…]