Lactobacillus plantarum bacteria, coloured scanning electron micrograph (SEM). This Gram-positive, rod prokaryote, non-spore forming, anaerobic or microaerophilic, bacterium occurs singly or in pairs. Very rarely pathogenic and is part of the normal flora in man and animals (mouth, vagina, and intestinal tract); "beneficial bacteria" or "probiotics". It has been reported to cause endocarditis, neonatal meningitis and bacteremia. Magnification: x2,600 when shortest axis printed at 25 millimetres.