Abstract
The genomes of the Betaproteobacteria Alicycliphilus denitrificans strains BC and K601T have been sequenced to get insight into the physiology of the two strains. Strain BC degrades benzene with chlorate as electron acceptor. The cyclohexanol-degrading denitrifying strain K601T is not able to use chlorate as electron acceptor, while strain BC cannot degrade cyclohexanol. The 16S rRNA sequences of strains BC and K601T are identical and the fatty acid methyl ester patterns of the strains are similar. Basic Local Alignment Search Tool (BLAST) analysis of predicted open reading frames of both strains showed most hits with Acidovorax sp. JS42, a bacterium that degrades nitro-aromatics. The genomes include strain-specific plasmids (pAlide201 in strain K601T and pAlide01 and pAlide02 in strain BC). Key genes of chlorate reduction in strain BC were located on a 120 kb megaplasmid (pAlide01), which was absent in strain K601T. Genes involved in cyclohexanol degradation were only found in strain K601T. Benzene and toluene are degraded via oxygenase-mediated pathways in both strains. Genes involved in the meta-cleavage pathway of catechol are present in the genomes of both strains. Strain BC also contains all genes of the ortho-cleavage pathway. The large number of mono- and dioxygenase genes in the genomes suggests that the two strains have a broader substrate range than known thus far.
Highlights
Microbialchlorate-reducing bacteria are able to produce oxygen as intermediate during anaerobic respiration with perchlorate and chlorate [1,2,3,4]
A. denitrificans strain K601T was isolated with cyclohexanol and nitrate as substrates [6]
We aimed to obtain insight in the physiological properties of A. denitrificans strains BC and K601T and in the pathways involved in degradation of aromatic and alicyclic compounds with different electron acceptors
Summary
Microbial (per)chlorate-reducing bacteria are able to produce oxygen as intermediate during anaerobic respiration with perchlorate and chlorate [1,2,3,4]. This process can create possible advantages in in-situ bioremediation of anaerobic environments where pollutants like aromatic hydrocarbons persist that are more prone to aerobic degradation [1,5]. Alicycliphilus denitrificans strain BC is able to couple benzene and toluene degradation to chlorate reduction [3]. A. denitrificans strain K601T was isolated with cyclohexanol and nitrate as substrates [6]. Contrary to strain BC, strain K601T lacks the chlorate-reducing capability. Strain BC, on the other hand, cannot degrade cyclohexanol [3,7]
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