Zoogloea oleivorans sp. nov., a floc-forming, petroleum hydrocarbon-degrading bacterium isolated from biofilm.

A floc-forming, Gram-stain-negative, petroleum hydrocarbon-degrading bacterial strain, designated Buc(T), was isolated from a petroleum hydrocarbon-contaminated site in Hungary. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Buc(T) formed a distinct phyletic lineage within the genus Zoogloea. Its closest relative was found to be Zoogloea caeni EMB43(T) (97.2% 16S rRNA gene sequence similarity) followed by Zoogloea oryzae A-7(T) (95.9%), Zoogloea ramigera ATCC 19544(T) (95.5%) and Zoogloea resiniphila DhA-35(T) (95.4%). The level of DNA-DNA relatedness between strain Buc(T) and Z. caeni EMB43(T) was 31.6%. Cells of strain Buc(T) are facultatively aerobic, rod-shaped, and motile by means of a polar flagellum. The strain grew at temperatures of 5-35 °C (optimum 25-28 °C), and at pH 6.0-9.0 (optimum 6.5-7.5). The predominant fatty acids were C16:0, C10 : 0 3-OH, C12:0 and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH). The major respiratory quinone was ubiquinone-8 (Q-8) and the predominant polar lipid was phosphatidylethanolamine. The genomic DNA G+C content was 63.2 mol%. On the basis of the chemotaxonomic, molecular and phenotypic data, isolate Buc(T) is considered to represent a novel species of the genus Zoogloea, for which the name Zoogloea oleivorans sp. nov. is proposed. The type strain is Buc(T) ( =DSM 28387(T) =NCAIM B 02570(T)).

The detection and phylogenetic analysis of the alkane 1-monooxygenase gene of members of the genus Rhodococcus.

Naturally occurring and anthropogenic petroleum hydrocarbons are potential carbon sources for many bacteria. The AlkB-related alkane hydroxylases, which are integral membrane non-heme iron enzymes, play a key role in the microbial degradation of many of these hydrocarbons. Several members of the genus Rhodococcus are well-known alkane degraders and are known to harbor multiple alkB genes encoding for different alkane 1-monooxygenases. In the present study, 48 Rhodococcus strains, representing 35 species of the genus, were investigated to find out whether there was a dominant type of alkB gene widespread among species of the genus that could be used as a phylogenetic marker. Phylogenetic analysis of rhodococcal alkB gene sequences indicated that a certain type of alkB gene was present in almost every member of the genus Rhodococcus. These alkB genes were common in a unique nucleotide sequence stretch absent from other types of rhodococcal alkB genes that encoded a conserved amino acid motif: WLG(I/V/L)D(G/D)GL. The sequence identity of the targeted alkB gene in Rhodococcus ranged from 78.5 to 99.2% and showed higher nucleotide sequence variation at the inter-species level compared to the 16S rRNA gene (93.9-99.8%). The results indicated that the alkB gene type investigated might be applicable for: (i) differentiating closely related Rhodococcus species, (ii) properly assigning environmental isolates to existing Rhodococcus species, and finally (iii) assessing whether a new Rhodococcus isolate represents a novel species of the genus.