1. Introduction
Probiotics are live microorganisms which have been found to confer health benefits on the host when administered in adequate amounts (FAO/WHO, 2002; Reid et al., 2003; Weichselbaum, 2009). A number of microorganism strains are being used as probiotics with different efficacies; some of them may provide certain benefits for the host whereas others do not (Weichselbaum, 2009). Many strains of bacteria have been used as probiotics, the most commonly used species being lactic acid bacteria such as Lactobacillus, Streptococcus and Bifidobacteria (Dunne et al., 2001).