Until now, there is no perfect agreement for set of criteria to select a viable bacterial strain as probiotics. According toิthe current definition by a joint FAO/WHO in 2002, probiotics are ‘Live microorganisms, which when administered in adequate
amounts, confer a health benefit on the host’. However, most of the current commercial probiotic products have not been screened for certain specific purpose but selected based on the concept of the survival potentiality (acid–bile test),
metabolically active within the gastrointestinal tract (adhesion assay), and biologically active against the identified target (pathogenic bacteria antagonization).