Phylogeny by a polyphasic approach of the order Caulobacterales, proposal of Caulobacter mirabilis sp. nov., Phenylobacterium haematophilum sp. nov. and Phenylobacterium conjunctum sp. nov., and emendation of the genus Phenylobacterium

Abstract

Phylogeny by a polyphasic approach of the order Caulobacterales, proposal of Caulobacter mirabilis sp. nov., Phenylobacterium haematophilum sp. nov. and Phenylobacterium conjunctum sp. nov., and emendation of the genus Phenylobacterium rRNA genes were determined for the genera Asticcacaulis, Brevundimonas, Caulobacter and Phenylobacterium and the description of the genus Phenylobacterium is emended.The genus Caulobacter was originally composed of dimorphic, prosthecate bacteria. In these prokaryotes, reproduction results in the separation of two cells that are morphologically and behaviourally different from each other. One cell is non-motile and prosthecate (Staley, 1968) and sticks to surfaces by adhesive material located at the tip of the prostheca. The other cell bears one polar flagellum by which it is motile. This mode of reproduction helps these oligotrophic bacteria to disperse the population at each generation, thereby minimizing competition for resources (Poindexter, 1981). Caulobacteria have been known for more than a century and the first isolation of a Caulobacter sp. was reported by Löffler in 1890 (Löffler, 1890). Even then, he noticed the unusual nutrient requirements of the strain due to the oligotrophic nature of the isolate. In 1935, Henrici and Johnson described the genus Caulobacter with Caulobacter vibrioides as the type species ) but they did not isolate C. vibrioides and therefore no type strain was given. Poindexter (1964) proposed strain CB 51 as the neotype strain of C. vibrioides and described nine species and two Figures showing a phylogenetic tree constructed from 16S rRNA gene sequences using the minimal evolution algorithm and the negative fast atom bombardment mass spectra of the polar lipids are available as supplementary material with the online version of this paper. Tables detailing the cellular fatty acid contents, phospho-and sulfolipids, polar lipids, enzyme activities and the results of the Biolog tests for the species examined in this study are given in supplementary tables S1-S5, available with the online version of this paper.

Phenylobacterium muchangponense sp. nov., isolated from beach soil, and emended description of the genus Phenylobacterium

“…This fatty acid profile is similar to those of closely related type strains except for the considerable amount of summed feature 4 and the absence of the hydroxy fatty acids C 12 : 0 3-OH and C 12 : 1 3-OH that are the main hydroxyl fatty acids of the genus Phenylobacterium (Abraham et al, 2008). ECL 18.084 was only found in strain A8 T .…”

“…The sequence similarity with 'Phenylobacterium zucineum' HLK1 was 97.8 %. Comparison of the 16S rRNA gene sequence of strain A8 T with those of other type strains of the genus Phenylobacterium revealed that strain A8 T was also missing nucleotides 71-88, 183-190, 206-211 and 452-476 (Escherichia coli numbering) (Abraham et al, 2008). Strain A8 T had 178-T, 1265-T and 1270-A, in agreement with P. composti 4T-6 T , P. immobile E T , P. koreense Slu-01 T , P. lituiforme Fail3 T , P. conjunctum FWC 21 T , P. haematophilum CCUG 26751 T and 'P.…”

“…Following those emendations, some members of the genus Phenylobacterium were shown not to grow on L-phenylalanine (Tiago et al, 2005) and the range of DNA G+C content was described as 64-72 mol% (Zhang et al, 2007). Recently, Abraham et al (2008) emended that cells of some species had prosthecae and all members of the genus contained a 16S rRNA gene signature sequence. At the time of writing, the genus Phenylobacterium comprises seven recognized species isolated from various environments, such as soil (Phenylobacterium immobile; Lingens et al, 1985), water (Phenylobacterium lituiforme; Kanso & Patel, 2004; Phenylobacterium falsum; Tiago et al, 2005), a rotating biological contactor (Phenylobacterium conjunctum; Abraham et al, 2008), activated sludge (Phenylobacterium koreense; Aslam et al, 2005), compost (Phenylobacterium composti; Weon et al, 2008) and blood (Phenylobacterium haematophilum; Abraham et al, 2008).…”

“…On the basis of new data obtained in this study, an emended description of the genus Phenylobacterium is also proposed. The description of the genus Phenylobacterium is as given by Lingens et al (1985), emended by Kanso & Patel (2004), emended by Tiago et al (2005), emended by Zhang et al (2007) and emended by Abraham et al (2008), with the following modifications. Utilization of antipyrine or chloridazon as sole carbon source, reduction of nitrate to nitrite, oxidase activity, and hydrolysis of casein are speciesdependent.…”

Asticcacaulis solisilvae sp. nov., isolated from forest soil

“…On the basis of the polar lipid analysis noted above and the recent characterization of novel species of Phenylobacterium (Abraham et al, 2008;Oh & Roh, 2012), genera of the family Caulobacteraceae can be distinguished by their composition of polar lipids. Among these genera, Asticcacaulis comprises prosthecate bacteria with, at the time of writing, four recognized species: Asticcacaulis excentricus (Poindexter, 1964), Asticcacaulis biprosthecium (Pate et al, 1973), Asticcacaulis taihuensis (Liu et al, 2005) and Asticcacaulis benevestitus (Vasilyeva et al, 2006).…”