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Novel Intermediates of Acenaphthylene Degradation by Rhizobium sp. Strain CU-A1: Evidence for Naphthalene-1,8-Dicarboxylic Acid Metabolism

Poonthrigpun, Siriwat, Pattaragulwanit, Kobchai, Paengthai, Sarunya, Kriangkripipat, Thanyanuch, Juntongjin, Kanchana, Thaniyavarn, Suthep, Petsom, Amorn, Pinphanichakarn, Pairoh
Applied and environmental microbiology 2006 v.72 no.9 pp. 6034-6039
Rhizobium, soil bacteria, biodegradation, polycyclic aromatic hydrocarbons, isolation, polluted soils, soil pollution, ribosomal RNA, genes, nucleotide sequences, metabolites, metabolism
The acenaphthylene-degrading bacterium Rhizobium sp. strain CU-A1 was isolated from petroleum-contaminated soil in Thailand. This strain was able to degrade 600 mg/liter acenaphthylene completely within three days. To elucidate the pathway for degradation of acenaphthylene, strain CU-A1 was mutagenized by transposon Tn5 in order to obtain mutant strains deficient in acenaphthylene degradation. Metabolites produced from Tn5-induced mutant strains B1, B5, and A53 were purified by thin-layer chromatography and silica gel column chromatography and characterized by mass spectrometry. The results suggested that this strain cleaved the fused five-membered ring of acenaphthylene to form naphthalene-1,8-dicarboxylic acid via acenaphthenequinone. One carboxyl group of naphthalene-1,8-dicarboxylic acid was removed to form 1-naphthoic acid which was transformed into salicylic acid before metabolization to gentisic acid. This work is the first report of complete acenaphthylene degradation by a bacterial strain.