#E1523D

Lactobacillus acidophilus and Lactobacillus casei from a probiotic soy protein preparation advertizing the presence of 50 billion live cells. The lactobacilli were grown as colonies on an agar gel plate to remove the interference from the soy proteins. L. acidophilus has long cells whereas L. casei has short curved cells (shown in yellow). Lactobacilli are probiotic lactic acid bacteria, the presence of which protect humans from some bacterial pathogens.