Lactobacillus spp. and Bifidobacterium spp. are mainly used as probiotics for humans and animals 35 However, other bacteria and fungi can also be used as probiotics. For example, Bacillus spp., Enterococcus spp., Streptococcus spp., and Saccharomyces cerevisiae seem to have potential as probiotics s In the screening and selection of certain microbial strains as probiotics, phenotype and genotype stability, carbohydrate and protein utilization patterns, safety, acid and bile stability, adhesion characterization, production of antimicrobial substances, antibiotic resis- tance patterns, immunogenicity, and viability and properties during processing and storage are considered to be important 36 B. subtilis is an aerobic spore-forming bacterium. B. subtilis spores are relatively resistant to oxygen, active oxygen species, acid, drying, and heating compared to other bacteria 27 B. subtilis can also grow under O2-reduced conditions. These characteristics are desirable for potential pro- biotics. Unfortunately, however, B. subtilis is not strongly resistant to bile acid and is not a predominant bacterium in the human intestine.37