Infant gut bacteria. Coloured scanning electron micrograph of Bifidobacteria infantis, which is the main bacterial species found in the large intestine of infants. It is also found in adults. It is present in small amounts in the vagina; it colonizes the baby's (originally sterile) gut during birth. It is beneficial to health, preventing the gut being colonized by harmful microbes, and producing B vitamins. It is used in probiotic" supplements claimed to improve health. Magnification unknown."