Polaromonas naphthalenivorans sp. nov., a naphthalene-degrading bacterium from naphthalene-contaminated sediment

Strain CJ2^T, capable of growth on naphthalene as a sole carbon and energy source, was isolated from coal-tar-contaminated freshwater sediment. The Gram reaction of strain CJ2^T was negative. The cells were non-spore-forming, non-motile cocci (without flagella). The isolate was found to be an aerobic heterotroph capable of utilizing glucose and other simple sugars. Growth was observed between 4 and 25 °C (optimum, 20 °C) and between pH 6.0 and 9.0 (optimum, pH 7.0-7.5). The G+C content of the genomic DNA was 61.5 mol% and the major quinone was ubiquinone-8. The peptidoglycan of strain CJ2^T was determined as belonging to type A1-γ, meso-diaminopimelic acid. The major fatty acids of strain CJ2^T were 16:1ω7c (67-0%), 16:0 (19.6%),18:1ω7c (∼7.9%) and 10:03-OH (∼2.5%). The polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. Mycolic acid and glycolipids could not be detected. Comparative 16S rDNA analysis indicated that strain CJ2^T is related to the family Comamonadaceae and that the nearest phylogenetic relative was Polaromonas vacuolata 34-P^T (97.1% similarity). On the basis of the physiological and molecular properties, the naphthalene-degrading isolate was designated Polaromonas naphthalenivorans sp. nov. The type strain is CJ2^T (=ATCC BAA-779^T= DSM 15660^T).