Probiotic bacteria are beneficial because they protect the body by keeping the harmful pathogens, such as candida, under control. They also stimulate the immune system to keep it ready to fight harmful disease organisms and heal the intestinal lining.
The human body contains around 7 pounds of beneficial bacteria, mostly in the intestines. Besides digestive bacteria such as Acidophilus, other bacteria have a number of functions in the body. Cyanocobalamin helps in the production of vitamin B12. Streptococcus mutans are found in the mouth and help convert sugar into lactic acid.
Other types of beneficial bacteria such as Bacillus subtilis are present in the soil to aid the growth and health of plants. Bacillus thuringiensis is a bacteria used as a natural pesticide for mosquitoes and caterpillars.