Cognitive development is Jean Piaget's theory. Through a series of stages, Piaget proposed four stages of cognitive development: the sensorimotor, preoperational, concrete operational and formal operational period.
The versatility of Bifidobacterium longum as a lactic acid microorganism is reflected in its capacity to resist under harsh conditions such as stomach acid, bile, pH fluctuations, and gastrointestinal passage.
Mycobacterium smegmatis is a common microorganism which, for a number of reasons, has become one of the most important bacteria for biological study. It is easy to culture and reproduces rapidly. It is non-pathogenic to humans and other animals.