Lactobacillus sp. Coloured Scanning Electron Micrograph (SEM) of the lactic acid-producing bacteria Lactobacillus sp. These are gram- positive, rod shaped bacteria (orange). Lactic acid producing bacteria are used extensively in the food industry, in areas such as bread, cheese and yoghurt production. Lactobacillus are found naturally and harmlessly occurring in humans and animals. They are part of the vaginal and intestinal flora. Although generally non- pathogenic, some strains of Lactobacillus are associated with disease. Magnification: x2,400 at 6x7cm size.