Bacillus pseudofirmus is a facultative anaerobe bacterium. It is a facultative anaerobe capable of aerobic respiration. The organism is a facultative anaerobe and is catalase-positive and motile. The organism is also a facultative anaerobe. "L. mirabilis" is a facultative anaerobe. It is a Gram-positive coccus, facultative anaerobe and catalase negative. It is the primary facultative anaerobe of the human gastrointestinal tract. It is a beta-hemolytic, catalase-negative, and facultative anaerobe. The probiotic "P. acidilactici" is a facultative anaerobe with lesser sensitivity to oxygen. It shows consistent growth throughout nutrient broth which is consistent with being a facultative anaerobe. It is a soil bacterium, and an obligate anaerobe. An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It is an obligate anaerobe with fermentative metabolism. In these cases, it can function as a facultative anaerobe. It is a gram-negative obligate anaerobe.