Hydroxyquinol, a common metabolite of aromatic compounds, is readily auto-oxidized to hydroxyquinone. Enzymatic activities that metabolized hydroxyquinone were observed from the cell extracts of Sphingobium chlorophenolicum ATCC 39723. An enzyme capable of transforming hydroxyquinone was partially purified, and its activities were characterized. The end product was confirmed to be 2,5-dihydroxyquinone by comparing UV/Vis absorption spectra, electrospray mass spectra, and gas chromatography-mass spectra of the end product and the authentic compound. We have proposed that the enzyme adds a H2O molecule to hydroxyquinone to produce 2,5-dihydroxycyclohex-2-ene-1, 4-dione, which spontaneously rearranges to 1, 2,4,5-tetrahydroxybenzene. The latter is auto-oxidized by O2 to 2,5-dihydroxyquinone. The proposed pathway was supported by the overall reaction stoichiometry. Thus, the transformation of hydroxyquinol to 2,5-dihydroxyquinone involves two auto-oxidation of quinols and one enzymatic reaction catalyzed by a hydratase. The specific enzymatic step did not require O2, further supporting the assignment as a hydratase. To our knowledge, this is the first identification of a quinone hydratase, enhancing the knowledge on microbial metabolism of hydroxyquinone and possibly leading to the development of enzymatic method for the production of 2,5-dihydroxyquinone, a widely used chemical in various industrial applications.

A novel actinomycete strain, SMC 256 T , which developed small, globose sporangia at the ends of long sporangiophores on aerial mycelium, was isolated from soil collected in a mountain forest of Thailand. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SMC 256 T belonged to the genus Kutzneria, and the closest phylogenetically related species were Kutzneria buriramensis BCC 29373 T (98.9 % 16S rRNA gene sequence similarity), Kutzneria kofuensis ATCC 27102 T (98.2 %), Kutzneria albida ATCC 25243 T (97.9 %) and Kutzneria viridogrisea ATCC 25242 T (97.4 %). The DNA-DNA relatedness values that distinguished strain SMC 256 T from previously described members of the genus Kutzneria were significantly below 70 %. The G+C content of the genomic DNA was 71.8 mol%. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars consisted of rhamnose, ribose, mannose, glucose and galactose. The predominant menaquinone was MK-9(H 4 ). Mycolic acids were not detected. The diagnostic phospholipids were hydroxyphosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides, unidentified phosphoglycolipids, unidentified phospholipids and an unidentified lipid. The predominant cellular fatty acids were iso-C 16 : 0 , C 17 : 1 and C 17 : 0 10-methyl. Following the evidence of phenotypic, chemotaxonomic and genotypic studies, it is proposed that strain SMC 256 T represents a novel species in the genus Kutzneria, namely Kutzneria chonburiensis sp. nov. The type strain is SMC 256 T (5BCC 72675 T 5NBRC 110610 T ).The genus Kutzneria was proposed by Stackebrandt et al. (1994) and classified in the family Pseudonocardiaceae. So far, this genus has consisted of four species: Kutzneria viridogrisea (type species), Kutzneria albida, Kutzneria kofuensis (Stackebrandt et al., 1994) and Kutzneria buriramensis (Suriyachadkun et al., 2013). Cells are Gram-stainpositive, non-acid-fast and aerobic. Large, globose sporangia (diameter, 10-48 mm) develop and contain rod-or ovalshaped, non-motile spores at the ends of long sporangiophores (length, .50 mm) on aerial mycelium. Substrate mycelium fragments into rod-shaped elements. Vegetative mycelium is white to pale yellow. Optimal growth is observed between 25 and 30 8C. The cell walls of the four established members of the genus Kutzneria contain Nacetylated muramic acid, meso-diaminopimelic acid and no common characteristic sugars. Mycolic acids are not detected. MK-9(H 4 ) is the major isoprenoid quinone. The phospholipid pattern is of type II and usually includes phosphatidylethanolamine, phosphatidylinositol, hydroxyphosphatidylethanolamine and diphosphatidylglycerol. The predominant cellular fatty acids are iso-C 16 : 0 , iso-C 16 : 0 2-OH, C 16 : 0 10-methyl, anteiso-C 17 : 0 , anteiso-C 17 : 0 2-OH and C 17 : 0 10-methyl. The G+C content of the genomic DNA is in the range of 70.3 to 72 mol%.During an investigation of actinomycete diversity in Thaila...

Sphingomonas (Flavobacterium) chlorophenolica ATCC 39723 degrades pentachlorophenol (PCP) through a catabolic pathway encoded by multiple genes. One gene required for PCP degradation is pcpA, which encodes information for a 30-kDa polypeptide, PcpA, found in the periplasm of the bacterium. The biological role of PcpA has remained unknown. We disrupted pcpA by replacing it with a defective copy through homologous recombination. The pcpA recombinant, mutant strains accumulated 2,6-dichlorohydroquinone (2,6-DiCH) as a metabolite of PCP. This work confirms that pcpA is essential for degradation of PCP by S. chlorophenolica ATCC 39723 and suggests that it encodes a protein involved in hydrolytic dehalogenation of 2,6-DiCH, an already established primary metabolite of the PCP catabolic pathway.