- Volume 71, Issue 5, 2021

A Gram-stain-negative, strictly aerobic and oval-shaped bacterial strain with a flagellum, designated GS-10T, was isolated from mangrove wetland sediment. GS-10T grew at 20–40 °C (optimum, 37 °C), in the pH range of 5.0–11.0 (optimum, 6.0–8.0) and under various NaCl concentrations from 1 to 11 % (w/v) (optimum, 5–6 %). The respiratory quinone was ubiquinone-10, and the predominant polar lipids were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids (>10 % of the total fatty acids) were summed feature 4 (C17 : 1iso I/anteiso B) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The G+C content of the genomic DNA was 63.71 %. On the basis of the results from comparative analysis of the 16S rRNA gene sequence, GS-10T represents a member of the family Rhodobacteraceae and had the highest sequence similarity to Thalassobius gelatinovorus CECT 4357T (97.47 %), followed by Lutimaribacter pacificus W11-2BT (97.03 %), Marivita cryptomonadis CL-SK44T (96.83 %), Thalassobius autumnalis CECT 5118T (96.75 %) and Thalassobius mediterraneus CECT 5383T (96.68 %). Phylogenetic trees based on 16S rRNA gene sequences, multilocus sequence analysis (MLSA) and whole genome sequences revealed that GS-10T clustered with species within the genus Thalassobius . The average nucleotide identity (ANI) and the average amino acid identity (AAI) values were calculated from complete genome sequences and indicated that GS-10T represented a novel species of the genus Thalassobius , and the name Thalassobius mangrovi sp. nov. is proposed for this species. The type strain of Thalassobius mangrovi is GS-10T (=MCCC 1K03624T=KCTC 82131T).

A novel Gram-reaction-negative bacterial strain, designated Ka43T, was isolated from agricultural soil and characterised using a polyphasic approach to determine its taxonomic position. On the basis of 16S rRNA gene sequence analysis, the strain shows highest similarity (97.1 %) to Cellvibrio diazotrophicus E50T. Cells of strain Ka43T are aerobic, motile, short rods. The major fatty acids are summed feature 3 (C16 : 1 ω7c and/or iso-C15 : 0 2-OH), C18 : 1  ω7c and C16 : 0. The only isoprenoid quinone is Q-8. The polar lipid profile includes phosphatidylethanolamine, phosphatidylglycerol, four phospholipids, two lipids and an aminolipid. The assembled genome of strain Ka43T has a total length of 4.2 Mb and the DNA G+C content is 51.6 mol%. Based on phenotypic data, including chemotaxonomic characteristics and analysis of the 16S rRNA gene sequences, it was concluded that strain Ka43T represents a novel species in the genus Cellvibrio , for which the name Cellvibrio polysaccharolyticus sp. nov. is proposed. The type strain of the species is strain Ka43T (=LMG 31577T=NCAIM B.02637T).

We isolated a novel strain, R1DC25T, described as Kaustia mangrovi gen. nov. sp. nov. from the sediments of a mangrove forest on the coast of the Red Sea in Saudi Arabia. This isolate is a moderately halophilic, aerobic/facultatively anaerobic Gram-stain-negative bacterium showing optimum growth at between 30 and 40 °C, at a pH of 8.5 and with 3–5 % NaCl. The genome of R1DC25T comprises a circular chromosome that is 4 630 536 bp in length, with a DNA G+C content of 67.3 mol%. Phylogenetic analyses based on the 16S rRNA gene sequence and whole-genome multilocus sequence analysis of 120 concatenated single-copy genes revealed that R1DC25T represents a distinct lineage within the family Parvibaculaceae in the order Rhizobiales within the class Alphaproteobacteria . R1DC25T showing 95.8, 95.3 and 94.5 % 16S rRNA gene sequence identity with Rhodoligotrophos appendicifer , Rhodoligotrophos jinshengii and Rhodoligotrophos defluvii , respectively. The predominant quinone was Q-10, and the polar lipids were phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, as well as several distinct aminolipids and lipids. The predominant cellular fatty acids were C19 : 0 cyclo ω8c, a combination of C18 : 1 ω7c and/or C18 : 1 ω6c and C16 : 0. On the basis of the differences in the phenotypic, physiological and biochemical characteristics from its known relatives and the results of our phylogenetic analyses, R1DC25T (=KCTC 72348T;=JCM 33619T;=NCCB 100699T) is proposed to represent a novel species in a novel genus, and we propose the name Kaustia mangrovi gen. nov., sp. nov. (Kaustia, subjective name derived from the abbreviation KAUST for King Abdullah University of Science and Technology; mangrovi, of a mangrove).

A Gram-stain negative, rod-shaped, facultatively aerobic, pale-beige-coloured bacterial strain, designated F7233T, was isolated from coastal sediment sampled at Jingzi Bay, Weihai, PR China. Cells of strain F7233T were 0.3–0.4 µm wide, 1.2–1.4 µm wide long, non-spore-forming and motile with one flagellum. Optimum growth occurred at 30 °C, with 1.0 % (w/v) NaCl and at pH 6.5–7.0. Positive for nitrate reduction, hydrolysis of Tweens and oxidase activity. The sole respiratory quinone of strain F7233T was ubiquinone-10 and the predominant cellular fatty acid was summed feature 8 (C18 : 1  ω7c/C18 : 1  ω6c). The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and one unidentified aminophospholipid. The G+C content of the chromosomal DNA was 63.3 mol%. Phylogenetic analysis of the 16S rRNA gene sequence revealed that the newly isolate belonged to the genus Stappia , with 96.8 % sequence similarity to Stappia indica MCCC 1A01226T, 96.1 % similarity to Stappia stellulata JCM 20692T and 95.5% similarity to Stappia taiwanensis CC-SPIO-10-1T. On the basis of phylogenetic, phenotypic and chemotaxonomic data, it is considered that strain F7233T should represent a novel species within the genus Stappia , for which the name Stappia albiluteola sp. nov. is proposed. The type strain is F7233T (=MCCC 1H00419T=KCTC 72859T).

We studied the taxonomic relationship between Streptomyces cinnamonensis and Streptomyces virginiae . These type strains shared the same 16S rRNA gene sequence. Phylogenomic analysis supported them being closely related. Digital DNA–DNA relatedness and average nucleotide identity using whole genome sequences indicated that the two species represent the same genomospecies. They shared similar phenotypic characteristics and harboured the same set of secondary metabolite-biosynthetic gene clusters for polyketides and nonribosomal peptides in the genomes. Therefore, according to Rule 24b of the Bacteriological Code, S. cinnamonensis Okami 1952, 572AL (Approved Lists 1980) should be reclassified as a later heterotypic synonym of S. virginiae Grundy et al. 1952, 399AL (Approved Lists 1980) emend. Nouioui et al. 2018. Although 16S rRNA gene sequences were identical among type strains of Streptomyces xanthophaeus , Streptomyces spororaveus and Streptomyces nojiriensis and between those of Streptomyces vinaceus and Streptomyces cirratus , respectively, digital DNA–DNA relatedness indicated that these species are not synonymous.

The strain Adlercreutzia caecicola DSM 22242T (=CCUG 57646T=NR06T) was taxonomically described in 2013 and named as Parvibacter caecicola Clavel et al. 2013. In 2018, the name of the strain DSM 22242T was changed to Adlercreutzia caecicola (Clavel et al. 2013) Nouioui et al. 2018 due to taxonomic investigations of the closely related genera Adlercreutzia, Asaccharobacter and Enterorhabdus within the phylum Actinobacteria . However, the first whole draft genome of strain DSM 22242T was published by our group in 2019. Therefore, the genome was not available within the study of Nouioui et al. (2018). The results of the polyphasic approach within this study, including phenotypic and biochemical analyses and genome-based taxonomic investigations [genome-wide average nucleotide identity (gANI), alignment fraction (AF), average amino acid identity (AAI), percentage of orthologous conserved proteins (POCP) and genome blast distance phylogeny (GBDP) tree], indicated that the proposed change of the name Parvibacter caecicola to Adlercreutzia caecicola was not correct. Therefore, it is proposed that the correct name of Adlercreutzia caecicola (Clavel et al. 2013) Nouioui et al. 2018 strain DSM 22242T is Parvibacter caecicola Clavel et al. 2013.