Hr. Beller et al., ISOLATION AND CHARACTERIZATION OF A NOVEL TOLUENE-DEGRADING, SULFATE-REDUCING BACTERIUM, Applied and environmental microbiology, 62(4), 1996, pp. 1188-1196
A novel sulfate-reducing bacterium isolated from fuel-contaminated sub
surface soil, strain PRTOL1, mineralizes toluene as the sole electron
donor and carbon source under strictly anaerobic conditions, The miner
alization of 80% of toluene carbon to CO2 was demonstrated in experime
nts with [ring-U-C-14]toluene; 15% of toluene carbon was converted to
biomass and nonvolatile metabolic by-products, primarily the former, T
he observed stoichiometric ratio of moles of sulfate consumed per mole
of toluene consumed was consistent with the theoretical ratio for min
eralization of toluene coupled with the reduction of sulfate to hydrog
en sulfide, Strain PRTOL1 also transforms o- and p-xylene to metabolic
products when grown with toluene. However, xylene transformation by P
RTOL1 is slow relative to toluene degradation and cannot be sustained
over time, Stable isotope-labeled substrates were used in conjunction,
vith gas chromatography-mass spectrometry to investigate the by-produc
ts of toluene and xylene metabolism, The predominant by-products from
toluene, o-xylene, and p-xylene were benzylsuccinic acid, (2-methylben
zyl)succinic acid, and 4-methylbenzoic acid (or p-toluic acid), respec
tively, Metabolic by-products accounted for nearly all of the o-xylene
consumed, Enzyme assays indicated that acetyl coenzyme A oxidation pr
oceeded via the carbon monoxide dehydrogenase pathway. Compared with t
he only other reported toluene-degrading, sulfate-reducing bacterium,
strain PRTOL1 is distinct in that it has a novel 16S rRNA gene sequenc
e and was derived from a freshwater rather than marine environment.