A genus of rod-shaped soil bacteria.
                                                            
                                                     
                        
                                                
                        
                        
                            a bacteria that was thought responsible for changing nitrite to nitrate (research disproves this; other bacteria are probably involved).
                                                            
                                                     
                        
                                                
                        
                        
                            A variety of air breathing bacteria, which convert nitrites to much less toxic nitrates.