Aurantimicrobium minutum gen. nov., sp. nov., a novel ultramicrobacterium of the family Microbacteriaceae, isolated from river water

Abstract

Aurantimicrobium minutum gen. nov., sp. nov., a novel ultramicrobacterium of the family Microbacteriaceae, isolated from river water Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashihiroshima, Hiroshima 739-8528, Japan A Gram-stain-positive, aerobic, non-motile, curved (selenoid), rod-shaped actinobacterium, designated KNC T , was isolated from the 0.2 mm-filtrate of river water in western Japan. Cells of strain KNC T were ultramicrosized (0.04-0.05 mm 3 ). The strain grew at 15-37 8C, with no observable growth at 10 8C or 40 8C. The pH range for growth was 7-9, with weaker growth at pH 10. Growth was impeded by the presence of NaCl at concentrations greater than 1 %. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain KNC T showed relatively high sequence similarity (97.2 %) to Alpinimonas psychrophila Cr8-25 T in the family Microbacteriaceae. However, strain KNC T formed an independent cluster with cultured, but as-yetunidentified, species and environmental clones on the phylogenetic tree. The major cellular fatty acids were anteiso-C 15 : 0 (41.0 %), iso-C 16 : 0 (21.8 %), C 16 : 0 (18.0 %) and anteiso-C 17 : 0 (12.9 %), and the major menaquinones were MK-11 (71.3 %) and MK-12 (13.6 %). The major polar lipids were phosphatidylglycerol and two unknown glycolipids. The cell-wall muramic acid acyl type was acetyl. The peptidoglycan was B-type, and contained 3-hydroxyglutamic acid, glutamic acid, aspartic acid, glycine, alanine and lysine, with the latter being the diagnostic diamino acid. The G+C content of the genome was unusually low for actinobacteria (52.1 mol%), compared with other genera in the family Microbacteriaceae. Based on the phenotypic characteristics and phylogenetic evidence, strain KNC T represents a novel species of a new genus within the family Microbacteriaceae, for which the name Aurantimicrobium minutum gen. nov., sp. nov. is proposed. The type strain of the type species is KNC T (5NBRC 105389 T 5NCIMB 14875 T ).The family Microbacteriaceae consists of predominantly aerobic Gram-positive actinobacteria that are differentiated from other families by a combination of their unusual cellwall peptidoglycan, unsaturated respiratory menaquinones and irregular cell shapes (Park et al., 1993;Evtushenko & Takeuchi, 2006). At the time of writing, the family comprised 44 genera with validly published names, including the recently described genera Glaciihabitans (Li et al., 2014) and Rhodoluna (Hahn et al., 2014).During the course of a study of ultramicrosized bacteria that could pass through 0.2 mm pore-size filters, which are generally used for sterile filtration to remove microorganisms from fluids, we isolated strains belonging to several novel taxa from various environments (Nakai et al., 2013(Nakai et al., , 2014. Here, one isolate, designated KNC T was characterized using a polyphasic approach. The results showed that strain KNC T represents a novel ultramicrobacterial lineage of the family Microbacteriaceae.Strain KNC T was originally i...

Component Microenvironments and System Biogeography Structure Microorganism Distributions in Recirculating Aquaculture and Aquaponic Systems

“…were most abundant in the aquaponic system samples but were absent or at very low relative abundances in all RAS samples. Both of these organisms are common members of freshwater lake/river microbial communities (44, 45). On the basis of this limited data set, it seems likely that aquaponic systems select for more-natural aquatic communities than those of RAS, presumably because of the availability of the plant-derived or phytoplankton-derived nutrients that are common in lakes/rivers and that would be available in these systems, e.g., glycolate for Polynucleobacter spp.…”

Effect of eco-remediation and microbial community using multilayer solar planted floating island (MS-PFI) in the drainage channel

“…Homology search against NCBI nr database of the sequences assigned to this genus suggested that Flavobacterium were potentially associated with assimilatory and dissimilatory of nitrogen compounds which are preceded by NO 3 - /NO 2 - transport into the cells. Alpinimonas isolated from river water and was likely to be important for dissolve organic matter removal (36). Norank_p_Saccharibacteria was a phylogenetically diverse group and played a role in the degradation of various organic compounds as well as sugar compounds under aerobic, nitrate reducing and anaerobic conditions (37).…”

Bacterium Lacking a Known Gene for Retinal Biosynthesis Constructs Functional Rhodopsins

“…A. minutum KNC T was originally isolated from a river in Japan (Nakai et al, 2015). The strain used in the present study was provided by the Biological Resource Center, NITE (NBRC) (Chiba, Japan).…”

“…We herein conducted a functional analysis of a rhodopsin and chemical analyses of pigments from the cosmopolitan freshwater Actinobacterium isolate, Aurantimicrobium minutum KNC T (Nakai et al, 2015), which belongs to the same family as R. lacicola. The A. minutum genome was reported in 2016 (Nakai et al, 2016); it contains a gene that encodes a putative light-driven, proton-pumping rhodopsin, Xanthorhodopsin (Balashov et al, 2005) -like rhodopsin (XLR), but lacks the blh gene.…”