clostridium fallax clostridium fallax clostridium fallax is an anaerobic, motile, gram-positive bacterium clostridium fallax scientific classification domain: bacteria phylum: bacillota class: clostridia order: eubacteriales family: clostridiaceae genus: clostridium species: c. fallax binomial name clostridium fallax(weinberg and séguin 1915) bergey et al. 1923