Pseudomonadales

An order mainly containing gram-negative rod-shaped bacteria with, in the motile forms, polar flagella. They do not form spores. Many species are pathogenic to plants, e.g. Pseudomonas tabaci and P. angulata, which cause wildfire and angular leaf spot of tobacco, and Xanthosomonas, which is responsible for various blights and cankers. The order also contains the nitrifying bacteria Nitrobacter and Nitrosomonas and the *photosynthetic bacteria.