Muricauda sediminis sp. nov., isolated from western Pacific Ocean sediment

Proposal of Allomuricauda gen. nov. and Allofranklinella gen. nov. as replacement names for the illegitimate prokaryotic generic names Muricauda and Franklinella, respectively

The prokaryotic generic names Muricauda Bruns et al. 2001 and Franklinella Bernard et al. 2022 are illegitimate because they are later homonyms of the genus names Muricauda Small 1903 (synonym of Arisaema; Tracheophyta - Liliopsida - Araceae) and Franklinella Stewart and Hendrix 1945 (a Devonian ostracod genus) and Franklinella Lenz 1973 (a Devonian brachiopod genus), respectively (Principle 2 and Rule 51b(4) of the International Code of Nomenclature of Prokaryotes). We therefore propose the replacement generic names Allomuricauda and Allofranklinella, with type species Allomuricauda ruestringensis and Allofrankinella schreckenbergeri, respectively.

Muricauda okinawensis sp. Nov. and Muricauda yonaguniensis sp. Nov., Two Marine Bacteria Isolated from the Sediment Core near Hydrothermal Fields of Southern Okinawa Trough

Two strains, 81s02^T and 334s03^T, were isolated from the sediment core near the hydrothermal field of southern Okinawa Trough. The cells of both strains were observed to be rod-shaped, non-gliding, Gram-staining negative, yellow-pigmented, facultatively anaerobic, catalase and oxidase positive, and showing optimum growth at 30 °C and pH 7.5. The strains 81s02^T and 334s03^T were able to tolerate up to 10% and 9% (w/v) NaCl concentration, respectively. Based on phylogenomic analysis, the average nucleotide identity (ANI) and the digital DNA-DNA hybridization (dDDH) values between the two strains and the nearest phylogenetic neighbors of the genus Muricauda were in range of 78.0-86.3% and 21.5-33.9%, respectively. The strains 81s02^T and 334s03^T shared 98.1% 16S rRNA gene sequence similarity to each other but were identified as two distinct species based on 81.4-81.5% ANIb, 85.5-85.6% ANIm and 25.4% dDDH values calculated using whole genome sequences. The strains 81s02^T and 334s03^T shared the highest 16S rRNA gene sequence similarity to M. lutimaris SMK-108^T (98.7%) and M. aurea BC31-1-A7^T (98.8%), respectively. The major fatty acid of strains 81s02^T and 334s03^T were identified similarly as iso-C_15:0, iso-C_17:0 3-OH and iso-C_15:1 G, and the major polar lipids of the both strains consisted of phosphatidylethanolamine and two unidentified lipids. The strains contained MK-6 as their predominant menaquinone. The genomic G+C contents of strains 81s02^T and 334s03^T were determined to be 41.6 and 41.9 mol%, respectively. Based on the phylogenetic and phenotypic characteristics, both strains are considered to represent two novel species of the genus Muricauda, and the names Muricauda okinawensis sp. nov. and Muricauda yonaguniensis sp. nov. are proposed for strains 81s02^T (=KCTC 92889^T = MCCC 1K08502^T) and 334s03^T (=KCTC 92890^T = MCCC 1K08503^T).

Muricauda chongwuensis sp. nov., isolated from coastal seawater of China

In the course of screening for bacterial predators, a Gram-stain-negative, non-flagellated, gliding, long rod-shaped, and yellow-pigmented bacterium, designated strain HICW^T, was isolated from coastal seawater of China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain HICW^T represented a member of the genus Muricauda and showed the highest sequence similarity to M. aquimarina JCM11811^T (98.8%) and M. ruestringensis DSM13258^T (98.1%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain HICW^T and M. aquimarina JCM11811^T were 79.2% and 34.1%, respectively. NaCl was required for growth. Optimum growth occurred at 25-30 °C, 2.0-3.0% (w/v) NaCl with pH 7.0. Strain HICW^T showed some similar characteristics to the nonobligate bacterial predators, and the cells can attach to the prey cells. Strain HICW^T contained MK-6 as the predominant respiratory quinone and had iso-C_15:0, iso-C_15:1 G, and iso-C_17:0 3-OH as the major cellular fatty acids. The polar lipids contained phosphatidylethanolamine (PE), three unidentified phospholipids (PL1-PL3), one unidentified amino lipids (AL), and three unidentified polar lipids (L1-L3). The genome size of strain HICW^T was approximately 3.8 Mbp, with a G + C content of 41.4%. Based on the polyphasic evidence, strain HICW^T is proposed as representing a new species of the genus Muricauda, for which the name Muricauda chongwuensis sp. nov. is proposed. The type strain is HICW^T (= JCM 33643 ^T = MCCC 1K03769^T).

Muricauda onchidii sp. nov., isolated from a marine invertebrate from South China Sea, and transfers of Flagellimonas algicola, Flagellimonas pacifica and Flagellimonas maritima to Muricauda algicola comb. nov., Muricauda parva nom. nov. and Muricauda aurantiaca nom. nov., respectively, and emended description of the genus Muricauda

An aerobic, Gram-stain-negative, rod-shaped and non-motile strain (XY-359^T) was isolated from the mouth of a marine invertebrate Onchidium species from the South China Sea. It grew at pH 6.0-8.5 (optimum, pH 7.5), at 15-37 °C (optimum, 30 °C) and in the presence of 0.5-4.5 % (w/v) NaCl (optimum, 2.5 %). It could not hydrolyse Tweens 20, 40, 60 or 80 and no flexirubin-type pigments were produced. The major polar lipids were phosphatidylethanolamine, one unidentified aminolipid, six unidentified phospholipids and two unidentified polar lipids. The major fatty acids were iso-C_17:0 3-OH, iso-C_15:1 G and iso-C_15:0 3-OH. The respiratory quinone was MK-6. Strain XY-359^T showed the greatest degree of 16S rRNA sequence similarity to Flagellimonas algicola AsT0115^T (96.54 %), followed by Muricauda flava DSM 22638^T (96.27 %). Phylogenetic analysis based on 16S rRNA gene sequences and 31 core genes indicated that strain XY-359^T belongs to the genus Muricauda. The genome size of strain XY-359^T was 4 207 872 bp, with 39.1 mol% of DNA G+C content. The average nucleotide identity and digital DNA-DNA hybridization values between strain XY-359^T and F. algicola AsT0115^T were 74.58 % and 18.5 %, respectively, and those between strain XY-359^T and M. flava DSM 22638^T were 74.2 % and 18.3 %. The combined phenotypic, chemotaxonomic and phylogenetic data suggest that strain XY-359^T represents a novel species of the genus Muricauda, for which the name Muricauda onchidii sp. nov. is proposed. The type strain is XY-359^T (=MCCC 1K03658^T =KCTC 72218^T). Moreover, based on the proposal of nesting Spongiibacterium and Flagellimonas within Muricauda by García (Validation List No. 193) and the analyses of phylogenetic trees and average amino acid identities in this study, the transfers of F. algicola, F. pacifica and F. maritima to the genus Muricauda as Muricauda algicola comb. nov., Muricauda parva nom. nov. and M. aurantiaca nom. nov., respectively, are proposed, with an emended description of the genus Muricauda.