selenomonas lacticifex selenomonas lacticifex selenomonas lacticifex is a species of anaerobic, gram-negative, rod-shaped bacteria first isolated from spoilt beer. selenomonas lacticifex scientific classification domain: bacteria phylum: bacillota class: negativicutes order: selenomonadales family: selenomonadaceae genus: selenomonas species: s. lacticifex binomial name selenomonas lacticifexschleifer et al. 1990