Anaerobic biotransformation of fluorene and phenanthrene by sulfate-reducing bacteria and identification of biotransformation pathway.
In the present study, anaerobic biotransformation of fluorene and phenanthrene by sulfate-reducing bacteria (SRB) was investigated and biotransformation pathways were proposed. SRB was enriched from anaerobic swine wastewater sludge and its abundance was determined by the fluorescence in situ hybridization (FISH) technique. Batch anaerobic biotransformation studies were conducted with fluorene (5 mg L(-1)), phenanthrene (5 mg L(-1)) and a mixture of the two (10 mg L(-1)). After 21d of incubation, 88% of fluorene and 65% of phenanthrene were biotransformed by SRB. In contrast to previous studies, a decrease in biotransformation efficiency was observed in the presence of both fluorene and phenanthrene. Throughout the study, sulfate reduction was coupled with biotransformation of fluorene and phenanthrene. However, no increase in bacterial cell density was observed in the presence of an inhibitor, i.e. molybdate. Identification of metabolites by gas chromatography-mass spectrometry (GC-MS) revealed that fluorene and phenanthrene were biotransformed through a sequence of hydration and hydrolysis reactions followed by decarboxylation with the formation of p-cresol (only in the phenanthrene system) and phenol. The metabolites identified suggest novel biotransformation pathways of fluorene and phenenthrene.
Tsai
Jen-Chieh
JC
Institute of Environmental Engineering, National Chiao Tung University, Hsinchu, Taiwan, ROC. vincent.ev92g@nctu.edu.tw
Kumar
Mathava
M
Lin
Jih-Gaw
JG
D000693:Anaerobiosis; D000818:Animals; D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D003408:Cresols; D005449:Fluorenes / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D017404:In Situ Hybridization, Fluorescence; D010616:Phenanthrenes / Q000378:metabolism*; D012722:Sewage / Q000382:microbiology; D013431:Sulfates / Q000378:metabolism; D013552:Swine; D014865:Waste Disposal, Fluid / Q000379:methods
D003408:Cresols; D005449:Fluorenes; D010616:Phenanthrenes; D012722:Sewage; D013431:Sulfates; C032538:4-cresol; C041509:fluorene; C031181:phenanthrene