2,3-Dihydroxybiphenyl dioxygenase gene was first discovered in Arthrobacter sp. strain PJ3

Abstract

Bacterium strain PJ3, isolated from wastewater and identified as Arthrobacter sp. bacterium based on its 16S rDNA gene, could use carbazole as the sole carbon, nitrogen and energy source. The genomic library of strain PJ3 was constructed and a positive clone JM109 (pUCW402) was screened out for the expression of dioxygenase by the ability to form yellow ring-fission product. A 2,3-dihydroxybiphenyl dioxygenase (23DHBD) gene of 933 bp was found in the 3360 bp exogenous fragment of pUCW402 by GenSCAN software and BLAST analysis. The phylogenetic analysis showed that 23DHBD from strain PJ3 formed a deep branch separate from a cluster containing most known 23DHBD in GenBank. Southern hybridization confirmed for the first time that the 23DHBD gene was from the genomic DNA of Arthrobacter sp. PJ3. In order to test the gene function, recombinant bacterium BL21 (pETW-8) was constructed to express 23DHBD. The expression level in BL21 (pETW-8) was highest compared with the recombinant bacteria JM109 (pUCW402) and strain PJ3. We observed that 23DHBD was not absolute specific. The enzyme activity was higher with 2,3-dihydroxybiphenyl as a substrate than with catechol. The substrate specificity assay suggested that 23DHBD was essential for cleavage of bi-cyclic aromatic compounds during the course of aromatic compound biodegradation in Arthrobacter sp. strain PJ3.2,3-dihydroxybiphenyl dioxygenase gene, Arthrobacter sp., phylogenetic tree, gene location, enzyme activity A number of plants synthesize an array of complex aromatic compounds and in some cases these substances or derived compounds may be released to the environment [1] . Aromatic compounds are thermally and chemically stable, persisting in the environment and accumulating as pollutants [2] . Mutations of microorganisms in the environment occur to alter their capacity to decompose these compounds into energy, carbon and nitrogen source to survive. Microbial degradation is thus an attractive means to remove aromatic compounds from the environment. Bacterial ring cleavage dioxygenases play a key role in degrading aromatic compounds for re-entry into the carbon cycle [3] and are of particular commercial interest because of their potential to effectively substitute chemical methods currently used in a variety of applications, especially environmental remediation of pollutants [4] .The major pathway for polychlorinated biphenyl (PCB) degradation is initiated by biphenyl dioxygenase, and the 3rd step is a meta-cleavage of the aromatic ring. This step is catalyzed by 2,3-dihydroxybiphenyl dioxygenase (23DHBD) which catalyzes the conversion of 2,3-dihydroxybiphenyl to 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) with the insertion of two atoms of oxygen [5] . 23DHBD has been found in various biphenyl-utilizing bacteria such as Beijerinckia sp. strain B1 [6] , Rhodococcus globerulus strain P6 [7] , and Sphingomonas sp. strain BN6 [8] .

Insight Into Metabolic Versatility of an Aromatic Compounds-Degrading Arthrobacter sp. YC-RL1

“… Péloquin and Greer (1993) obtained the gene cluster (DNA fragment, not the complete sequence information) contributed to the degradation of biphenyl and sequenced the partial sequence of bphC . Yang M. et al (2007) identified and characterized BphC in Arthrobacter PJ3. The identification of complete gene clusters involved in the degradation of biphenyl, especially the identification of the novel bph gene cluster, would advance the investigation of biphenyl metabolism.…”

Isolation and identification of a carbazole degradation gene cluster from Sphingomonas sp.JS1

“…Carbazole 1, 9 a-dioxygenase was encoded by carAaAcAd or carA; metacleavage enzyme was encoded by carBaBb or carB, and the meta-cleavage compound hydrolase was encoded by carC, respectively Genomic DNA of strain JS1 digested with XhoI was separated by electrophoresis in a 0.8% (w/v) agarose gel and blotted onto a nylon membrane. Gene Images TM DNA labeling and detection kit (Amersham Biosciences) were used as described elsewhere (Yang et al 2007). The probe used was 825 bp PCR fragment of carC from the car gene cluster (2,260-3,083 nt) of JS1.…”

Reservoir Characteristics of Reef-Shoal Facies, Changxing Formation, Yuanba Gasfield, Sichuan Basin

“…1). Marginal platform reef and shoal carbonates were first found in the Upper Permian Changxing Formation and the Lower Triassic Feixianguan Formation at the outcrops in the west of the Kaijiang-Liangping Shelf [3,4] . Therefore, the Yuanba area was recognized as a favorable place for marginal platform reef and shoal development.…”