L. casei is a fastidious microorganism
(Cai et al., 2009; Du Toit et al., 2011) and the pool of free amino
acids and peptides in milk is not sufficient to fulfill optimal bacterial
growth. Thus, the phage-induced release of the S. thermophilus cell
lysate, which contains proteases, lactase, free amino acids, and peptides,
accelerates the growth and propagation of the probiotic. Probiotic
growth is then further enhanced, as the decrease in viable
S. thermophilus cells also eliminates the competition between this
bacterium and the probiotic for nutrients in the media