Loktanella salsilacus gen. nov., sp. nov., Loktanella fryxellensis sp. nov. and Loktanella vestfoldensis sp. nov., new members of the Rhodobacter group, isolated from microbial mats in Antarctic lakes

Abstract

A taxonomic study was performed on 26 strains isolated from microbial mats in Antarctic lakes of the Vestfold Hills and the McMurdo Dry Valleys. Phylogenetic analysis based on 16S rRNA gene sequences placed these strains within the Rhodobacter group of the α-subclass of the Proteobacteria. Sequence similarity values for the strains with their nearest phylogenetic neighbours (Jannaschia, Octadecabacter and Ketogulonicigenium) ranged between 94·0 and 95·8 %. DNA–DNA hybridizations and comparison of repetitive extragenic palindromic DNA–PCR (rep-PCR) fingerprinting patterns revealed that these strains are members of three distinct species. The isolates are Gram-negative, chemoheterotrophic, non-motile rods and their DNA G+C contents range from 59·4 to 66·4 mol%. Whole-cell fatty acid profiles are similar and the primary fatty acid in all the strains is 18 : 1 ω7c (74·1–87·7 % of total). Genotypic results together with phenotypic characteristics allowed the differentiation of these species from related recognized species of the α-Proteobacteria and the strains are assigned to a new genus, Loktanella gen. nov., with three novel species: Loktanella salsilacus sp. nov. (type species), consisting of ten strains with LMG 21507T (=CIP 108322T) as type strain; Loktanella fryxellensis sp. nov., consisting of 12 strains with LMG 22007T (=CIP 108323T) as type strain; and Loktanella vestfoldensis sp. nov., consisting of four strains with LMG 22003T (=CIP 108321T) as type strain.

Anaerobic phototrophic nitrite oxidation by Thiocapsa sp. strain KS1 and Rhodopseudomonas sp. strain LQ17

“…Photosynthetic bacteria can be found in almost every aquatic environment, including freshwater, marine, alkaline, acidic and hot or cold waters (Pfennig, 1976(Pfennig, , 1978Stanier et al, 1981;Trüper & Pfennig, 1981;Van Trappen et al, 2004;Caumette et al, 2004;Herbert et al, 2005;Asao et al, 2007). In addition to these natural environments, purple anoxygenic phototrophs also inhabit engineered systems, such as wastewater treatment facilities, although their role there is not well understood.…”

Loktanella litorea sp. nov., isolated from seawater

“…As of the time of writing, seven additional species of the genus Loktanella with validly published names, Loktanella hongkongensis (Lau et al, 2004), Loktanella agnita and Loktanella rosea (Ivanova et al, 2005), Loktanella koreensis (Weon et al, 2006), Loktanella maricola (Yoon et al, 2007), Loktanella atrilutea (Hosoya & Yokota, 2007) and Loktanella pyoseonensis (Moon et al, 2010), have been described. Members of the genus Loktanella have been isolated from Antarctic lakes, marine biofilms, sea sands, seawater and marine sediment (Van Trappen et al, 2004;Lau et al, 2004;Ivanova et al, 2005;Weon et al, 2006;Yoon et al, 2007;Hosoya & Yokota, 2007;Moon et al, 2010). In this study, we describe a bacterial strain resembling members of the genus Loktanella, designated DPG-5 T , which was isolated from seawater of the South Sea, Korea.…”

“…The genus Loktanella was first proposed by Van Trappen et al (2004) with the description of three novel species, Loktanella salsilacus (the type species), Loktanella fryxellensis and Loktanella vestfoldensis. As of the time of writing, seven additional species of the genus Loktanella with validly published names, Loktanella hongkongensis (Lau et al, 2004), Loktanella agnita and Loktanella rosea (Ivanova et al, 2005), Loktanella koreensis (Weon et al, 2006), Loktanella maricola (Yoon et al, 2007), Loktanella atrilutea (Hosoya & Yokota, 2007) and Loktanella pyoseonensis (Moon et al, 2010), have been described.…”

Thalassobius mediterraneus gen. nov., sp. nov., and reclassification of Ruegeria gelatinovorans as Thalassobius gelatinovorus comb. nov.

“…Novel taxa are continuously arising within this group. Thus, since that review of names, 16 proposals of novel species and nine new genera of a-3 Proteobacteria have been published in the International Journal of Systematic and Evolutionary Microbiology (Abraham et al, 2004;Adachi et al, 2004;Cho & Giovannoni, 2004;Lau et al, 2004;Lee et al, 2004;Martínez-Cánovas et al, 2004;Shieh et al, 2004;Van Trappen et al, 2004;Wagner-Döbler et al, 2004;Labrenz et al, 2005;Macián et al, 2005a, b;Pujalte et al, 2005) and a few others are currently in press. Such a concentration of papers and independent studies on the same bacterial group implies that exhaustive care has to be taken with the criteria for proposing novel taxa and their arrangement into higher rank units.…”