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Isolation and characterization of Alicycliphilus denitrificans strain BC, which grows on benzene with chlorate as the electron acceptor

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Author: Weelink, S.A.B. · Tan, N.C.G. · Broeke, H. ten · Kieboom, C. van den · Doesburg, W. van · Langenhoff, A.A.M. · Gerritse, J. · Junca, H. · Stams, A.J.M.
Type:article
Date:2008
Institution: TNO Bouw en Ondergrond
Source:Applied and Environmental Microbiology, 21, 74, 6672-6681
Identifier: 241078
Keywords: Geosciences · Biochemistry · Biodegradation · Catalysts · Cell culture · Degradation · Encoding (symbols) · Enzymes · Gene encoding · Genes · Nitrates · Oxygen · Oxygenation · Proteins · Benzene biodegradations · Benzene degradations · Biochemical datum · Cyclohexanol · Dioxygenase enzymes · Dismutase · Dismutation · Electron acceptors · Encoding · Enrichment cultures · External- · Gene sequences · Genes encoding · In cells · Isolation and characterizations · Monooxygenase · Monooxygenations · Organic molecules · Oxygenase · Oxygenases · Pcr primers · Primer sets · Short rods · Benzene · bacterial enzyme · benzene · benzene oxygenase · catechol · catechol 1,2 dioxygenase · chlorate · chlorite dismutase · estradiol dioxygenase · nitrate · oxygenase · unclassified drug · bacterium · benzene · biochemistry · biodegradation · catabolism · chlorite · denitrification · detection method · electron · enzyme activity · gene expression · mutation · nitrate · oxic conditions · oxygen · polymerase chain reaction · Alicycliphilus denitrificans · article · bacterial growth · bacterial strain · bacterium isolate · biodegradation · electron transport · energy yield · gene amplification · gene sequence · genetic code · nonhuman · nucleotide sequence · oxygenation · phylogeny · polymerase chain reaction · Proteobacteria · unindexed sequence · Bacterial Proteins · Benzene · Chlorates · Comamonadaceae · Dioxygenases · DNA, Bacterial · DNA, Ribosomal · Genes, rRNA · Locomotion · Mixed Function Oxygenases · Molecular Sequence Data · Nitrates · Nitrites · Nitrogen · Oxidoreductases · Oxygen · Phylogeny · Polymerase Chain Reaction · RNA, Bacterial · RNA, Ribosomal, 16S · Sequence Analysis, DNA · Sequence Homology, Nucleic Acid · Alicycliphilus denitrificans · Bacteria (microorganisms) · Negibacteria

Abstract

A bacterium, strain BC, was isolated from a benzene-degrading chlorate-reducing enrichment culture. Strain BC degrades benzene in conjunction with chlorate reduction. Cells of strain BC are short rods that are 0.6 μm wide and 1 to 2 μm long, are motile, and stain gram negative. Strain BC grows on benzene and some other aromatic compounds with oxygen or in the absence of oxygen with chlorate as the electron acceptor. Strain BC is a denitrifying bacterium, but it is not able to grow on benzene with nitrate. The closest cultured relative is Alicycliphilus denitrificans type strain K601, a cyclohexanol-degrading nitrate-reducing betaproteobacterium. Chlorate reductase (0.4 U/mg protein) and chlorite dismutase (5.7 U/mg protein) activities in cell extracts of strain BC were determined. Gene sequences encoding a known chlorite dismutase (cld) were not detected in strain BC by using the PCR primers described in previous studies. As physiological and biochemical data indicated that there was oxygenation of benzene during growth with chlorate, a strategy was developed to detect genes encoding monooxygenase and dioxygenase enzymes potentially involved in benzene degradation in strain BC. Using primer sets designed to amplify members of distinct evolutionary branches in the catabolic families involved in benzene biodegradation, two oxygenase genes putatively encoding the enzymes performing the initial successive monooxygenations (BC-BMOa) and the cleavage of catechol (BC-C23O) were detected. Our findings suggest that oxygen formed by dismutation of chlorite can be used to attack organic molecules by means of oxygenases, as exemplified with benzene. Thus, aerobic pathways can be employed under conditions in which no external oxygen is supplied. Copyright © 2008, American Society for Microbiology. All Rights Reserved.