Leptospira Biflexa, a free living, saprophytic species of the genus Leptospira, order Spirochaetales, unlike other Leptospira, the organism can not cause diseases in human. L. Biflexa display a helical structure and wave-shaped morphology and were discovered in a filtrate on July 13, 1913. The cell is 20 µm long and 0.1 µm in diameter, whose cytoplasm and outer membrane are similar to Gram-negative bacteria. L. Biflexa are found all over the world, except in Antarctica yet. General cultivation condition involves incubation in Ellinghausen-McCullough-Johnson-Harris (EMJH) medium at 30°C and the growth of saprophytic strains usually begin in 2-3 days. Compared to those pathogenic species, L. Biflexa have characteristics of easy to culture in vitro and uncomplicated genetic manipulation, so often being used as a model for other Leptospira research.