Bacillus cereus strain PU, isolated from soil contaminated with explosive waste, tolerated up to 1.3 mM 2,4,6 trinitrophenol (TNP) and utilize it aerobically as sole nitrogen and carbon source. Degradation of TNP was accompanied by stoichiometric release of 2.1 +/- A 0.15 mol nitrite/mol TNP at 539 mu mol/h g dry cell wt. Metabolism of TNP was accompanied by transient accumulation of an orange-red metabolite, hydride meisenheimer complex (H-TNP), indicating a metabolic pathway involving complete reductive removal of the nitro group as nitrite.