Lacinutrix chionocetis sp. nov., isolated from gut of a red snow crab

An Update on Novel Taxa and Revised Taxonomic Status of Bacteria (Including Members of the Phylum Planctomycetota) Isolated from Aquatic Host Species Described in 2018 to 2021

Increased interest in farmed aquatic species, aquatic conservation measures, and microbial metabolic end-product utilization have translated into a need for awareness and recognition of novel microbial species and revisions to bacterial taxonomy. Because this need has largely been unmet, through a 4-year literature review, we present lists of novel and revised bacterial species (including members of the phylum Planctomycetota) derived from aquatic hosts that can serve as a baseline for future biennial summaries of taxonomic revisions in this field. Most new and revised taxa were noted within oxidase-positive and/or nonglucose fermentative Gram-negative bacilli, including members of the Tenacibaculum, Flavobacterium, and Vibrio genera. Valid and effectively published novel members of the Streptococcus, Erysipelothrix, and Photobacterium genera are additionally described from disease pathogenesis perspectives.

Two Novel Lyso-Ornithine Lipids Isolated from an Arctic Marine Lacinutrix sp. Bacterium

The Lacinutrix genus was discovered in 2005 and includes 12 Gram-negative bacterial species. To the best of our knowledge, the secondary metabolite production potential of this genus has not been explored before, and examination of Lacinutrix species may reveal novel chemistry. As part of a screening project of Arctic marine bacteria, the Lacinutrix sp. strain M09B143 was cultivated, extracted, fractionated and tested for antibacterial and cytotoxic activities. One fraction had antibacterial activity and was subjected to mass spectrometry analysis, which revealed two compounds with elemental composition that did not match any known compounds in databases. This resulted in the identification and isolation of two novel isobranched lyso-ornithine lipids, whose structures were elucidated by mass spectrometry and NMR spectroscopy. Lyso-ornithine lipids consist of a 3-hydroxy fatty acid linked to the alpha amino group of an ornithine amino acid through an amide bond. The fatty acid chains were determined to be iso-C15:0 (1) and iso-C16:0 (2). Compound 1 was active against the Gram-positive S. agalactiae, while 2 showed cytotoxic activity against A2058 human melanoma cells.

Phenotypic and Molecular Characterization of Lacinutrix venerupis Isolated from Atlantic Horse Mackerel Trachurus trachurus

The aim of the present study was to characterize two gram-negative bacterial strains that were isolated from diseased Atlantic Horse Mackerel Trachurus trachurus in 2017. Based on the results obtained from the biochemical and chemotaxonomic characterization, the isolates were identified as Lacinutrix spp. The highest similarity of the 16S rRNA gene sequences was obtained with the strain L. venerupis CECT 8573^T (99.1%), while other species showed similarities of 98% (L. jangbogonensis) and 97% (L. algicola and L. mariniflava). Molecular characterization by repetitive element (REP)-PCR and enterobacterial repetitive intergenic consensus (ERIC)-PCR, as well as proteomic characterization by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS), demonstrated heterogeneity between the strains from the Atlantic Horse Mackerel and the type strain, CECT 8573^T . The virulence of one of the isolates for Turbot Scophthalmus maximus, European Sea Bass Dicentrarchus labrax, Senegalese Sole Solea senegalensis, and Rainbow Trout Oncorhynchus mykiss was assessed under experimental conditions. No mortalities were recorded after intraperitoneal injections with high doses of bacteria (1 × 10⁹  CFU/mL). Thus, further studies are necessary to elucidate the impact of this bacterial species as a fish pathogen.

A strategy for securing unique microbial resources – focusing on Dokdo islands-derived microbial resources

This review focuses on the state of research on the microbial resources of Dokdo, Korea, as a strategy for securing national microbial resources. In the Korean peninsula, studies aimed at securing microbial resources are carried out across diverse natural environments, especially in the Dokdo islands. Until 2017, a total of 61 novel microbial genera, species, or newly recorded strains have been reported. Among these, 10 new taxa have had their whole genome sequenced and published, in order to find novel useful genes. Additionally, there have been multiple reports of bacteria with novel characteristics, including promoting plant growth or inducing systemic resistance in plants, calcite-forming ability, electrical activation, and production of novel enzymes. Furthermore, fundamental studies on microbial communities help to secure and define microbial resources in the Dokdo islands. This study will propose several tactics, based on ecological principles, for securing more microbial resources to cope with the current increase in international competition for biological resources.

Description of Lacinutrix salivirga sp. nov., a marine member of the family Flavobacteriaceae isolated from seawater

A novel marine bacterium, designated KMU-57^T, was isolated from seawater collected from the Republic of Korea, and it was characterized using polyphasic taxonomic methods. Strain KMU-57^T was Gram-stain-negative, strictly aerobic, rod-shaped, motile and dark-yellow-pigmented. Comparative analysis based on the 16S rRNA gene sequence showed the affiliation of the isolate with members of the family Flavobacteriaceae of the phylum Bacteroidetes, and it had the greatest sequence similarity (97.6%) to Lacinutrix jangbogonensis PAMC 27137^T. The DNA-DNA relatedness value between strain KMU-57^T and L. jangbogonensis PAMC 27137^T was 37.8 ± 2.2%. The DNA G + C content of strain KMU-57^T was 29.9 mol%; MK-6 was the major menaquinone with; iso-C15:1 G (18.6%) and C16:1 ω7c and/or C16:1 ω6c (15.8%) as the major (> 10%) cellular fatty acids. The polar lipid profile consisted of phosphatidylethanolamine, three unidentified aminolipids, and five unidentified lipids. The strain represents a novel species of the genus Lacinutrix for which the name Lacinutrix salivirga sp. nov. is proposed. The type strain of L. salivirga sp. nov. is KMU-57^T (= KCTC 52878^T = NBRC 112845^T).