Animated coloured scanning electron micrograph (SEM) of Lactobacillus salivarius is homofermentative, probiotic bacterium that lives in the human gastrointestinal tract. It is a genus of Gram-positive, facultative anaerobic or microaerophilic rod-shaped bacterium. L. salivarius is a common probiotic bacterium, due to its ability to inhibit the growth of other bacteria and tolerate host antimicrobial defences. It is an economically important lactic acid bacterium that is homofermentative, where by its fermentation process results in a single end product beginning with a carbohydrate. Studies concerning the treatment of adult atopic dermatitis often use this bacterium as a model. L. salivarius produces bacteriocins (oligopeptides, proteins or protein complexes) that have antimicrobial properties that act against other strains of bacteria. Magnification: x2, 935 when shortest axis printed at 25 millimetres.