Genome sequence of the deltaproteobacterial strain NaphS2 and analysis of differential gene expression during anaerobic growth on naphthalene

• Published in: PloS one 2010-11, Vol.5 (11), p.e14072
• Main Authors: DiDonato, Jr, Raymond J, Young, Nelson D, Butler, Jessica E, Chin, Kuk-Jeong, Hixson, Kim K, Mouser, Paula, Lipton, Mary S, DeBoy, Robert, Methé, Barbara A
• Format: Article
• Language: English
• Subjects: Acids; Anaerobiosis; Analysis; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Benzoates - chemistry; Benzoates - metabolism; Biological products; Carboxylation; Contaminated sediments; Deltaproteobacteria - genetics; Deltaproteobacteria - metabolism; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Drosophila; Environmental degradation; Enzymes; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Bacterial - drug effects; Gene sequencing; Genes; Genetic aspects; Genetic research; Genetics and Genomics/Functional Genomics; Genetics and Genomics/Gene Expression; Genetics and Genomics/Genomics; Genetics and Genomics/Microbial Evolution and Genomics; Genome, Bacterial - genetics; Genomes; Genomics; Geobacter metallireducens; Growth; Hydrocarbons; Insects; Klebsiella pneumoniae; Laboratories; Metabolic Networks and Pathways; Metabolism; Microbiology/Microbial Evolution and Genomics; Microbiology/Microbial Physiology and Metabolism; Microorganisms; Molecular Structure; Naphthalene; Naphthalenes - chemistry; Naphthalenes - metabolism; Naphthalenes - pharmacology; Nucleotide sequence; Oligonucleotide Array Sequence Analysis; Oxidation-Reduction; Physiological aspects; Polycyclic aromatic hydrocarbons; Proteins; Proteomics; Reverse Transcriptase Polymerase Chain Reaction; Sediment pollution; Sediments; Sediments (Geology); Sequence Analysis, DNA - methods; Studies; Sulfate reduction; Sulfates; Sulfates - metabolism; Toluene; Toluene - chemistry; Toluene - metabolism; Transcription
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0014072

Anaerobic polycyclic hydrocarbon (PAH) degradation coupled to sulfate reduction may be an important mechanism for in situ remediation of contaminated sediments. Steps involved in the anaerobic degradation of 2-methylnaphthalene have been described in the sulfate reducing strains NaphS3, NaphS6 and N47. Evidence from N47 suggests that naphthalene degradation involves 2-methylnaphthalene as an intermediate, whereas evidence in NaphS2, NaphS3 and NaphS6 suggests a mechanism for naphthalene degradation that does not involve 2-methylnaphthalene. To further characterize pathways involved in naphthalene degradation in NaphS2, the draft genome was sequenced, and gene and protein expression examined. Draft genome sequencing, gene expression analysis, and proteomic analysis revealed that NaphS2 degrades naphthoyl-CoA in a manner analogous to benzoyl-CoA degradation. Genes including the previously characterized NmsA, thought to encode an enzyme necessary for 2-methylnaphthalene metabolism, were not upregulated during growth of NaphS2 on naphthalene, nor were the corresponding protein products. NaphS2 may possess a non-classical dearomatizing enzyme for benzoate degradation, similar to one previously characterized in Geobacter metallireducens. Identification of genes involved in toluene degradation in NaphS2 led us to determine that NaphS2 degrades toluene, a previously unreported capacity. The genome sequence also suggests that NaphS2 may degrade other monoaromatic compounds. This study demonstrates that steps leading to the degradation of 2-naphthoyl-CoA are conserved between NaphS2 and N47, however while NaphS2 possesses the capacity to degrade 2-methylnaphthalene, naphthalene degradation likely does not proceed via 2-methylnaphthalene. Instead, carboxylation or another form of activation may serve as the first step in naphthalene degradation. Degradation of toluene and 2-methylnaphthalene, and the presence of at least one bss-like and bbs-like gene cluster in this organism, suggests that NaphS2 degrades both compounds via parallel mechanisms. Elucidation of the key genes necessary for anaerobic naphthalene degradation may provide the ability to track naphthalene degradation through in situ transcript monitoring.