Characterization of the microaerophilic, bacteriochlorophyll a-containing bacterium Gemmatimonas phototrophica sp. nov., and emended descriptions of the genus Gemmatimonas and Gemmatimonas aurantiaca

Abstract

A red-pigmented, bacteriochlorophyll (BChl) a-producing strain, AP64T, was isolated previously from the freshwater Swan Lake located in the western Gobi Desert. Based on its 16S rRNA gene sequence identity (96.1 %) to the type strain Gemmatimonas aurantiaca T-27T, the new isolate was tentatively classified as a member of the bacterial phylum Gemmatimonadetes. Here, we report its formal description and polyphasic characterization. Strain AP64T grew best on agar media under 9.8–15.2 % atmospheric oxygen. The cells were rods, dividing by symmetrical or asymmetrical binary fission. Budding structures were also observed. Its genomic DNA G+C content was 64.4 % (from the draft genome sequence). Phylogenetic analysis based on the 16S rRNA gene sequence clearly separated AP64T from related species. Its genotypic differentiation from phylogenetically close relatives was further supported by performing in silico DNA–DNA hybridization and calculating average nucleotide identity, whereas the high percentage (67.3 %) of shared conserved proteins between strain AP64T and Gemmatimonas aurantiaca T-27T supports the classification of the two strains into the same genus. Strain AP64T contained C16 : 1, C14 : 1 and C18 : 1ω9c as predominant fatty acids. The main respiratory quinone was menaquinone 8 (MK-8). The most distinctive feature of strain AP64T was the presence of fully functional purple bacterial photosynthetic reaction centres. The main CO2-fixation pathways were absent. Strain AP64T was capable of growth and BChl production in constant darkness. Thus, strain AP64T is a facultatively photoheterotrophic organism. It represents a novel species of the genus Gemmatimonas, for which the name Gemmatimonas phototrophica sp. nov. is proposed. The type strain is AP64T ( = DSM 29774T = MCCC 1K00454T). Emended descriptions of the genus Gemmatimonas and Gemmatimonas aurantiaca are also provided.

Longimicrobium terrae gen. nov., sp. nov., an oligotrophic bacterium of the under-represented phylum Gemmatimonadetes isolated through a system of miniaturized diffusion chambers

“…In broth medium, cells did not flocculate and showed a whitishpink colour. 'Gemmatirosa kalamazoonensis' ATCC BAA-2150 flocculated in broth medium, whereas Gemmatimonas phototrophica AP64 T was reported to be unable to grow in liquid media (Zeng et al, 2015).…”

“…Unless otherwise noted, CB-286315 T and the reference strains were grown under normal atmospheric conditions at 25 8C using R2A medium solidified with 1.5 % (w/v) noble agar or in R2A broth for 15 days at 28 8C in the dark for inoculum or sample preparation. Since Gemmatimonas phototrophica AP64 T only grew well on agar plates (Zeng et al, 2015), its inclusion in parallel analyses based on broth cultures was not possible. However, Gemmatimonas phototrophica AP64 T was characterized by Zeng et al (2015) under comparable growth conditions.…”

“…Since Gemmatimonas phototrophica AP64 T only grew well on agar plates (Zeng et al, 2015), its inclusion in parallel analyses based on broth cultures was not possible. However, Gemmatimonas phototrophica AP64 T was characterized by Zeng et al (2015) under comparable growth conditions. Strain CB-286315 T was found to be a Gram-negative bacterium according to a 3 % KOH assay (Powers, 1995) and Gram staining and oxidase-positive and catalase-positive based on tests with 1 % (w/v) N,N,N9,N9-tetramethyl p-phenylenediamine dihydrochloride and 3 % (v/v) hydrogen peroxide solutions, respectively.…”

“…Within this class, two genera, Gemmatimonas and 'Gemmatirosa', have been proposed. The first genus harbours two species, Gemmatimonas aurantiaca and Gemmatimonas phototrophica (Zeng et al, 2015), both only represented by the type strains. Gemmatimonas aurantiaca T-27 T was isolated from a laboratory-scale anaerobic-aerobic sequential batch reactor operated under excess biological phosphorus removal , whereas Gemmatimonas phototrophica AP64 T , a microaerophilic, bacteriochlorophyll a-containing bacterium, was isolated from a freshwater lake (Zeng et al, 2015).…”

“…The first genus harbours two species, Gemmatimonas aurantiaca and Gemmatimonas phototrophica (Zeng et al, 2015), both only represented by the type strains. Gemmatimonas aurantiaca T-27 T was isolated from a laboratory-scale anaerobic-aerobic sequential batch reactor operated under excess biological phosphorus removal , whereas Gemmatimonas phototrophica AP64 T , a microaerophilic, bacteriochlorophyll a-containing bacterium, was isolated from a freshwater lake (Zeng et al, 2015). The genus 'Gemmatirosa' comprises a single species, 'Gemmatirosa kalamazoonensis', of which the proposed type strain KBS708 was isolated from an organically managed agricultural soil (DeBruyn et al, 2013).…”