Aquiluna borgnonia gen. nov., sp. nov., a member of a Microbacteriaceae lineage of freshwater bacteria with small genome sizes

Abstract

The actinobacterial strain 15G-AUS-rotT was isolated from an artificial pond located near Salzburg, Austria. The strain showed 16S rRNA gene sequence similarities of 98.7 % to Candidatus Aquiluna rubra and of 96.6 and 96.7 % to the two validly described species of the genus Rhodoluna . Phylogenetic reconstructions based on 16S rRNA gene sequences and genome-based on amino acid sequences of 118 single copy genes referred strain 15G-AUS-rotT to the family Microbacteriaceae and therein to the so-called subcluster Luna-1. The genome-based phylogenetic tree showed that the new strain represents a putative new genus. Cultures of strain 15G-AUS-rotT were light red pigmented and comprised very small, rod-shaped cells. They metabolized a broad variety of substrates. Major fatty acids (>10 %) of cells were iso-C16 : 0, antiso-C15 : 0 and iso-C14 : 0. The major respiratory quinone was MK-11 and a minor component was MK-10. The peptidoglycan structure belonged to an unusual B type. The closed genome sequence of the strain was very small (1.4 Mbp) and had a DNA G+C content of 54.8 mol%. An interesting feature was the presence of genes putatively encoding the complete light-driven proton pumping actinorhodopsin/retinal system, which were located at three different positions of the genome. Based on the characteristics of the strain, a new genus and a new species termed Aquiluna borgnonia is proposed for strain 15G-AUS-rotT (=DSM 107803T=JCM 32974T).

Complete Genome Sequence of Aquiluna sp. Strain KACHI24, Isolated from River Surface Water

“…Bacterioplankton belonging to the genus Aquiluna bacteria have worldwide distribution, including freshwater and marine environments ( 1 – 3 ). However, the lack of archived and reported sequences belonging to this genus is mainly a result of limited success in isolating a pure culture ( 2 , 3 ).…”

“…Bacterioplankton belonging to the genus Aquiluna bacteria have worldwide distribution, including freshwater and marine environments ( 1 – 3 ). However, the lack of archived and reported sequences belonging to this genus is mainly a result of limited success in isolating a pure culture ( 2 , 3 ). Therefore, accessing the genomic information of Aquiluna bacteria is important for the estimation of physiochemical and ecological insights into the genus.…”

Aurantimicrobium photophilum sp. nov., a non-photosynthetic bacterium adjusting its metabolism to the diurnal light cycle and reclassification of Cryobacterium mesophilum as Terrimesophilobacter mesophilus gen. nov., comb. nov.

“…Strains KNC T and MWH-Mo1 T were tested in parallel for growth at various NaCl concentrations (0.0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 %) as described previously [13]. The two strains differed in growth at concentrations >0.7 % NaCl (Table 1).…”

“…Strains MWH-Mo1 T and KNC T were tested in parallel for some physiological traits as described previously [13]. Both were catalase-positive and oxidase-negative.…”

“…Only genomes of strains affiliated with the genera Rhodoluna [15,21] and Aquiluna [13,22] The genomes of strain MWH-Mo1 T and A. minutum KNC T were compared for orthologous proteins by using the OrthoVenn2 software [24]. The analysis was performed by setting an E-value threshold of 1e −15 and an inflation value of 1.5.…”