Phenylobacterium lituiforme sp. nov., a moderately thermophilic bacterium from a subsurface aquifer, and emended description of the genus Phenylobacterium

Abstract

A facultative anaerobic bacterium, strain FaiI3T, was isolated from samples collected from the free-flowing waters of a bore well (Fairlea Bore, registration number 3768) which taps into the Australian Great Artesian Basin subsurface thermal aquifer. Strain FaiI3Tdeveloped yellow to pale-yellow colonies (0·5–1·5 mm) after 48 h. The non-spore forming rods (0·5×1–3 μm) were slightly curved, occurred singly and as pairs and were motile with a single polar flagellum. Cells tended to form clumps in liquid medium and rosettes were commonly observed. The cells stained Gram-negative and electron micrographs of thin sections revealed a multi-layered complex Gram-negative cell wall structure. Strain FaiI3Tgrew optimally at 40–41 °C, with growth observed at 45 °C but not at 50 °C. The pH growth range was between pH 6 and 9 and optimal growth occurred between pH 6 and 6·5. Strain FaiI3Tgrew best with yeast extract as the sole carbon and energy source. Peptone, yeast extract, acetate, xylose, sucrose, glucose, glycerol, succinate, butyrate, lactate, fumarate, citrate,l-phenylalanine, cellobiose and gelatin supported growth but maltose, fructose, glycine, ethanol, benzoate and oxalate did not. Tyrosine was produced froml-phenylalanine. Strain FaiI3Twas catalase-positive and oxidase-negative and did not hydrolyse starch. Growth was inhibited by neomycin, tetracycline, streptomycin, chloramphenicol, ampicillin, vancomycin and spectinomycin. The G+C content was determined to be 66·5±0·5 mol%. On the basis of the 16S rRNA gene sequence analysis, strain FaiI3Twas assigned as a novel species of the genusPhenylobacterium,Phenylobacterium lituiformesp. nov. in the orderCaulobacterales, subclassα-Proteobacteria, classProteobacteria. The type strain is FaiI3T(=ATCC BAA-294T=DSM 14363T).