Sf. Nishino et Jc. Spain, OXIDATIVE PATHWAY FOR THE BIODEGRADATION OF NITROBENZENE BY COMAMONASSP STRAIN JS765, Applied and environmental microbiology, 61(6), 1995, pp. 2308-2313
Previous studies have shown that the biodegradation of nitrobenzene by
Pseudomonas pseudoalcaligenes JS45 proceeds by the reduction of nitro
benzene through nitrosobenzene and hydroxylaminobenzene, followed by r
earrangement to 2-aminophenol, which then undergoes meta ring cleavage
, We report here the isolation of a Comamonas sp. that uses an oxidati
ve pathway for the complete mineralization of nitrobenzene. The isolat
e, designated strain JS765, uses nitrobenzene as a sole source of carb
on, nitrogen, and energy, Nitrobenzene-grown cells oxidized nitrobenze
ne, with the stoichiometric release of nitrite, Extracts of nitrobenze
ne-grown JS765 showed high levels of catechol 2,3-dioxygenase activity
that were not abolished by heating the cell extracts to 60 degrees C
for 10 min, The ring cleavage product had an absorbance maximum at 375
nm, consistent, with that of 2-hydroxymuconic semialdehyde. Both NAD-
dependent dehydrogenase and NAD-independent hydrolase activities towar
ds 2-hydroxymuconic semialdehyde were induced in extracts of nitrobenz
ene-grown cells. Catechol accumulated in the reaction mixture when cel
ls preincubated with 3-chlorocatechol were incubated with nitrobenzene
. Conversion of nitrobenzene to catechol by induced cells in the prese
nce of 3-chlorocatechol and O-18(2), demonstrated the simultaneous inc
orporation of two atoms of oxygen, which indicated that the initial re
action was dioxygenation. The results indicate that the catabolic path
way involves an initial dioxygenase attack on nitrobenzene with the re
lease of nitrite and formation of catechol, which is subsequently degr
aded by a meta cleavage pathway.