Abstract
Probiotics are live microbes which when administered in adequate amounts as functional food ingredients confer a health benefit on the host. Their versatility is in terms of their usage which ranges from the humans to the ruminants, pigs and poultry, and also in aquaculture practices. In this review, the microorganisms frequently used as probiotics in human and animal welfare has been described, and also highlighted are the necessary criteria required to be fulfilled for their use in humans on the one hand and on the other as microbial feed additives in animal husbandry. Further elaborated in this article are the sources from where probiotics can be derived, the possible mechanisms by which they act, and their future potential role as antioxidants is also discussed.