Classification of a Violacein-Producing Psychrophilic Group of Isolates Associated with Freshwater in Antarctica and Description of Rugamonas violacea sp. nov.

• Published in: Microbiology Spectrum
• Main Authors: Ivo Sedláček, Pavla Holochová, Roman Sobotka, Hans-Jürgen Busse, Pavel Švec, Stanislava Králová, Ondrej Šedo, Jan Pilný, Eva Staňková, Vendula Koublová, Karel Sedlář
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society for Microbiology 2021
• Subjects: psychrophiles; Rugamonas; taxonomy; Antarctica; violacein; species description; Microbiology; QR1-502; Ross Island; Antarc*; James Ross Island
• Online Access: https://doi.org/10.1128/Spectrum.00452-21; https://doaj.org/article/ddd99319c8e94ca18e3a2fbb1cc26de0

ABSTRACT A group of 11 bacterial strains was isolated from streams and lakes located in a deglaciated northern part of James Ross Island, Antarctica. They were rod-shaped, Gram-stain-negative, motile, and catalase-positive and produced blue-violet-pigmented colonies on R2A agar. A polyphasic taxonomic approach based on 16S rRNA gene sequencing, whole-genome sequencing, automated ribotyping, repetitive element sequence-based PCR (rep-PCR), MALDI-TOF MS, fatty acid profile, chemotaxonomy analyses, and extensive biotyping was applied in order to clarify the taxonomic position of these isolates. Phylogenetic analysis based on the 16S rRNA gene indicated that all the isolates constituted a coherent group belonging to the genus Rugamonas. The closest relatives to the representative isolate P5900T were Rugamonas rubra CCM 3730T, Rugamonas rivuli FT103WT, and Rugamonas aquatica FT29WT, exhibiting 99.2%, 99.1%, and 98.6% 16S rRNA pairwise similarity, respectively. The average nucleotide identity and digital DNA-DNA hybridization values calculated from the whole-genome sequencing data clearly proved that P5900T represents a distinct Rugamonas species. The G+C content of genomic DNAs was 66.1 mol%. The major components in fatty acid profiles were summed feature 3 (C16:1 ω7c/C16:1 ω6c), C 16:0, and C12:0. The cellular quinone content contained exclusively ubiquinone Q-8. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. The polyamine pattern was composed of putrescine, 2-hydroxputrescine, and spermidine. IMPORTANCE Our polyphasic approach provides a new understanding of the taxonomy of novel pigmented Rugamonas species isolated from freshwater samples in Antarctica. The isolates showed considerable extracellular bactericidal secretions. The antagonistic activity of studied isolates against selected pathogens was proved by this study and implied the importance of such compounds’ production among aquatic bacteria. The psychrophilic and violacein-producing species ...