Review Article

The microbial population in the gastro-intestinal (GI) tract is very complex and consists of different groups of microbes and the GI system is the place where complex interactions occur between feed, microbes and host cells. Probiotics, which are live microorganisms provides a positive impact on the host by altering the intestinal microbial balance, thus helping to reduce the harmful effects of pathogenic bacteria in the gut. In livestock as well as poultry, probiotics has been shown to improve growth performance, feed conversion efficiency and immune responses. They exert there action by competitive exclusion or producing antibacterial substances that are detrimental to pathogenic microbes. Similarly, prebiotics, which are non-digestible feed supplements, are selectively fermented by beneficial microflora and are utilized by them to exclude the pathogenic microbes. These non-digestible substrates comprises of oligosaccharides which also has the ability to stimulate absorption of several minerals in intestine. Also, nowadays, combination of probiotics and prebiotics (synbiotics) are effectively used to counter the negative impact of stress factors or pathogens in animal and poultry production systems. Presently, the prospects of identifying or evolving novel strains of probiotics using various modern amenities and techniques have been explored. For this purpose, polymerase chain reaction (PCR) technique, 16S rRNA sequencing, real time PCR and microarray techniques are utilized. These techniques are capable to assess the influence and interaction of intestinal microflora on host systems. The technique of genetic engineering has also been used to modify the effects of existing strains or to create novel probiotics that can play multiple roles in the intestinal environment.