BIODEGRADATION OF 4-NITROTOLUENE BY PSEUDOMONAS SP STRAIN 4NT

A strain of Pseudomonas spp. was isolated from nitrobenzene-contaminat ed soil on 4-nitrotoluene as the sole source of carbon, nitrogen, and energy. The organism also grew on 4-nitrobenzyl alcohol, 4-nitrobenzal dehyde, and 4-nitrobenzoate. 4-Nitrobenzoate and ammonia were detected in the culture fluid of glucose-grown cells after induction with 4-ni trotoluene. Washed suspensions of 4-nitrotoluene- or 4-nitrobenzoate-g rown cells oxidized 4-nitrotoluene, 4-nitrobenzaldehyde, 4-nitrobenzyl alcohol, and protocatechuate. Extracts from induced cells contained 4 -nitrobenzaldehyde dehydrogenase, 4-nitrobenzyl alcohol dehydrogenase, and protocatechuate 4,5-dioxygenase activities. Under anaerobic condi tions, cell extracts converted 4-nitrobenzoate or 4-hydroxylaminobenzo ate to protocatechuate. Conversion of 4-nitrobenzoate to protocatechua te required NADPH. These results indicate that 4-nitrotoluene was degr aded by an initial oxidation of the methyl group to form 4-nitrobenzyl alcohol, which was converted to 4-nitrobenzoate via 4-nitrobenzaldehy de. The 4-nitrobenzoate was reduced to 4-hydroxylaminobenzoate, which was converted to protocatechuate. A protocatechuate 4,5-dioxygenase ca talyzed meta-ring fission of the protocatechuate. The detection of 4-n itrobenzaldehyde and 4-nitrobenzyl alcohol dehydrogenase and 4-nitroto luene oxygenase activities in 4-nitrobenzoate-grown cells suggests tha t 4-nitrobenzoate is an inducer of the 4-nitrotoluene degradative path way.