Paludibacillus litoralis gen. nov., sp. nov.: a novel species of a novel genus in the family Paracoccaceae, isolated from the sediment of a tidal flat located in Zhoushan, China

A Gram-stain-negative, aerobic and rod-shaped bacterium, designated as HZG-20T, was isolated from a tidal flat in Zhoushan, Zhejiang Province, China. The 16S rRNA sequence similarities between strain HZG-20T and Pikeienuella piscinae RR4-56T, Coraliihabitans acroporae NNCM2T, Parvibaculum indicum P31T and Zhengella mangrovi X9-2-2T were 98.9, 91.7, 91.0 and 91.0%, respectively. Colonies of strain HZG-20T were 1.4 mm in diameter, milky white, round, smooth and convex after cultivating on marine agar at 30 °C for 48 h. Cells were catalase and oxidase-negative. Growth occurred at 15-37 ℃ (optimum, 28 ℃), pH 5.0-9.0 (optimum, pH 6.0-8.0) and with 0-8% (w/v) NaCl (optimum, 1-3%). It contained Menaquinone-8 (H2) as the sole respiratory quinone, and C16:0 (11.8-13.6%), C18:1  ω9c (6.8-13.3%) and C15:0 anteiso (10.9-27.7%) as the major cellular fatty acids. The main polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminolipid, one unidentified phosphoglycolipid, two unidentified glycolipids (GL1-GL2) and three unidentified lipids (L1-L3). The genome of strain HZG-20T was 3 835 886 bp in length, comprised 3746 protein-coding genes, with DNA G+C content of 67.1 mol%. The phylogenetic and phylogenomic trees indicated that strain HZG-20T formed an independent and stable clade with P. piscinae RR4-56T. However, the average nucleotide identity, digit DNA-DNA hybridization and average amino acid identity values between strain HZG-20T and P. piscinae RR4-56T, C. acroporae NNCM2T, P. indicum P31T and Z. mangrovi X9-2-2T were 81.6, 71.1, 68.7 and 69.5%; 23.0, 18.5, 17.9 and 17.5%; and 78.2, 56.8, 56.5 and 61.9%, respectively, together with distinct chemotaxonomic features, indicating strain HZG-20T should not be assigned to known genera. As a result, a novel species of a novel genus within the family Paracoccaceae, designated as Paludibacillus litoralis gen. nov., sp. nov., was proposed. The type strain is HZG-20T (MCCC 1K08468T=KCTC 82692T).

Thermophilic microorganisms involved in the nitrogen cycle in thermal environments: Advances and prospects

Thermophilic microorganisms mediated significant element cycles and material conversion in the early Earth as well as mediating current thermal environments. Over the past few years, versatile microbial communities that drive the nitrogen cycle have been identified in thermal environments. Understanding the microbial-mediated nitrogen cycling processes in these thermal environments has important implications for the cultivation and application of thermal environment microorganisms as well as for exploring the global nitrogen cycle. This work provides a comprehensive review of different thermophilic nitrogen-cycling microorganisms and processes, which are described in detail according to several categories, including nitrogen fixation, nitrification, denitrification, anaerobic ammonium oxidation, and dissimilatory nitrate reduction to ammonium. In particular, we assess the environmental significance and potential applications of thermophilic nitrogen-cycling microorganisms, and highlight knowledge gaps and future research opportunities.

Algicella marina gen. nov., sp. nov., a novel marine bacterium isolated from a Pacific red alga

A novel Gram-staining negative, strictly aerobic, rod-shaped, and non-motile bacterium, designated strain 9Alg 56^T, was isolated from the red alga Tichocarpus crinitus. The phylogenetic analysis based on 16S rRNA gene sequences placed the novel strain within the family Rhodobacteraceae, the order Rhodobacterales, the class Alphaproteobacteria, the phylum Pseudomonadota. The nearest neighbors of the new strain were Pontivivens insulae KCTC 42458^T, Oceanibium sediminis KCTC 62076^T, Halovulum dunhuangense YYQ-30^T and Monaibacterium marinum C7^T with 16S rRNA gene sequence similarity of 94.7, 94.4%, 93.1 and 92.7%, respectively. The AAI/ANI/dDDH values between 9Alg 56^T and the five species of the closest genera (Pontivivens, Oceanibium, Halovulum, Monaibacterium, and 'Oceanomicrobium') were 58.63-63.91%/ 75.91-77.37%/ 19.3-20.4%. The prevalent fatty acids of strain 9Alg 56^T were C_18:1 ω7c, C_18:0 and C_14:0 3-OH. The polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol, phosphatidic acid, phosphatidylcholine, and two unidentified lipids. The DNA G+C content of strain 9Alg 56^T was 61.5 mol%. A combination of the genotypic and phenotypic data showed that the algal isolate represents a novel genus and species, for which the name Algicella marina gen. nov., sp. nov. is proposed. The type strain is 9Alg 56^T (= KCTC 72005^T = KMM 6775^T).

Roseitranquillus sediminis gen. nov., sp. nov. a novel genus and species of the family Rhodobacteraceae, isolated from sediment of an Arctic fjord

A Gram-negative, aerobic, non-motile, oxidase-positive, catalase-positive, rod-shaped bacterium, designated strain MCCB 386^T was isolated from sediment samples collected from Kongsfjorden, an Arctic fjord. The strain MCCB 386^T showed growth at 4-37 °C (optimum 27°C) in the presence of 1-8% NaCl (w/v, optimum 3.5%) and at pH 6.0-8.0 (optimum pH 7.0). The major fatty acids were C_18:1ω7c (54.0%) and 11-methyl C_18:1ω7c (22.6%). The dominant respiratory quinone was Q-10. The major polar lipids comprised of phosphatidylcholine (PC), diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphoglycolipid (PGL), one unidentified aminolipid, two glycolipids and two unidentified lipids. The genomic G+C content of the strain MCCB 386^T was 68.1 mol%. The 16 S rRNA gene sequences based phylogenetic analysis of MCCB 386^T showed that Psychromarinibacter halotolerans YBW34^T (95.88%) is the most closely related species. In addition, overall genome relatedness indices (OGRI) of MCCB 386^T with closely related strains were lower than threshold level for species and genus delineation. The analysis of Biosynthetic Gene clusters (BGCs) revealed the potential of this strain for production of novel bioactive secondary metabolites. As per polyphasic taxonomic characterisation, strain MCCB 386^T represents a novel species of a novel genus for which the name Roseitranquillus sediminis gen. nov., sp. nov. is suggested. The type strain of the species is MCCB 386^T (= JCM 33,538^T= KACC 21,531^T).

Pikeienuella piscinae gen. nov., sp. nov., a novel genus in the family Rhodobacteraceae

A novel bacterium, designated strain RR4-56T, was isolated from a biofilter of a seawater recirculating aquaculture system. The 16S rRNA gene sequence analysis showed that the isolate was closely related to Halovulum dunhuangense YYQ-30T (92.6%), Albimonas donghaensis DS2T (91.3%), Pontivivens insulae GYSW-23T (91.3%), and Monaibacterium marinum C7T (90.9%), belonging to the family Rhodobacteraceae. The strain was aerobic, Gram-negative, rod-shaped, oxidase-positive, and catalase-negative. Its optimum temperature, pH, and salinity for growth were 25-30°C, pH 8.5, and 2-3% NaCl (w/v), respectively. Its growth occurred at 15-35°C, pH 5.0-9.5, and 0-7% NaCl (w/v). It contained ubiquinone-10 (Q-10), a respiratory quinone, and the major cellular fatty acids were 11-methyl C18:1 ω7c (31.9%), C18:1 ω6c (30.4%), and C19:0 cyclo ω8c (16.1%). The polar lipids present in the strain were phosphatidylglycerol, an unidentified phospholipid, and an unidentified aminolipid. The strain had one 4,373,045 bp circular chromosome with G + C contents of 65.9 mol% including 4,169 genes, 4,118 coding sequences (CDSs), 3 rRNAs, and 45 tRNAs. Genome annotation predicted some gene clusters related to the degradation of several types of organic matter such as protocatechuate, catechol, and phthalate. Based on the polyphasic characteristics, RR4-56T represents a novel genus and species in the family Rhodobacteraceae, for which the name Pikeienuella piscinae gen. nov., sp. nov. was proposed. The type strain is RR4-56T (= KCTC 52648T = DSM 107918T).

Oceanomicrobium pacificus gen. nov., sp. nov., a member of the family Rhodobacteraceae isolated from seawater of tropical western Pacific

The Gram-stain-negative, aerobic, ovoid or rod-shaped bacterial strain, designated KN286^T, was isolated from seawater of tropical western Pacific. Growth occurred between 15 and 40 °C (optimally at 30-35 °C), pH 6-9 (optimally at 7.0) and in the presence of 0.5-5.0% (w/v) NaCl (optimally between 2.0 and 3.0%). Strain KN286^T contained Q-10 as the major respiratory quinone. The polar lipid profile contained phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, three phospholipids, three glycolipids, and three unidentified polar lipids. The predominant cellular fatty acid was summed feature 8 (composed of C_18:1ω7c and/or C_18:1ω6c). Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain KN286^T was a member of the family Rhodobacteraceae and formed a distinct lineage. Strain KN286^T has a genome size of 3.25 Mbp and a G + C content of 65.0 mol%. It encoded with some genes for carbohydrate-active enzymes, such as GH20 (Glycoside Hydrolase Family 20) and PL1 (Polysaccharide Lyase Family 1) and did not encode with a set of genes for reduction of nitrate to nitrite (nitrate reductase gamma subunit, respiratory nitrate reductase alpha N-terminal and respiratory nitrate reductase beta C-terminal). Based on phylogenetic analyses with single-copy orthologous clusters, low isDDH value (19.6%), low ANI (72.4%) and low AAI (65.7%) results, differential chemotaxonomic and physiological properties, strain KN286^T represents a novel species of a novel genus of the family Rhodobacteraceae, for which the name Oceanomicrobium pacificus gen. nov., sp. nov. is proposed. The type strain of Oceanomicrobium pacificus is KN286^T (=CGMCC 1.17118^T = KCTC 72430^T).

Halovulum marinum sp. nov., isolated from deep-sea water of the Indian Ocean, and emended description of the genus Halovulum

A novel Gram-stain-negative, aerobic, motile by peritrichous flagella, oval to rod-shaped bacterium, designated strain 2CG4^T, was isolated from a deep-sea water sample collected from the Northwest Indian Ocean. The results of phylogenetic analysis of both 16S rRNA gene and RpoC protein sequences indicated that this strain was affiliated with the genus Halovulum in the Amaricoccus clade of the family Rhodobacteraceae of the class Alphaproteobacteria, sharing 95.3 % similarity at the 16S rRNA gene sequence level with the type strain of Halovulum dunhuangense YYQ-30^T, the only species in the genus Halovulum. The predominant fatty acids (>10 %) of 2CG4^T were summed feature 8 (C_18 : 1ω7c and/ or C_18 : 1ω6c; 61.1 %) and cyclo-C_19 : 0ω8c (15.6 %). The polar lipids of 2CG4^T were phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine and sulfoquinovosyldiacylglycerol. The only isoprenoid quinone of 2CG4^T was ubiquinone-10. The DNA G+C content of 2CG4^T was determined to be 69.4 %. The central gene pufLM for the photosynthetic reaction was not detected. No growth occurred for 2CG4^T in the absence of NaCl. On the basis of these data, it is concluded that the 2CG4^T represents a novel species of the genus Halovulum, for which the name Halovulum marinum sp. nov. is proposed. The type strain is 2CG4^T (=CGMCC 1.16468^T=JCM 32611^T).

Pseudopontivivens aestuariicola gen. nov., sp. nov., a Novel Bacterium of the Class Alphaproteobacteria Isolated from a Tidal Flat

A Gram-stain-negative, non-motile and coccoid, ovoid or rod-shaped bacterial strain, OITF-57^T, which was isolated from a tidal flat sediment in South Korea, was characterized taxonomically. Strain OITF-57^T grew optimally at 25 °C, at pH 7.0-8.0 and in the presence of 2.0% (w/v) NaCl. Strain OITF-57^T exhibited the highest 16S rRNA gene sequence similarity value (94.2%) to the type strain of Pontivivens insulae forming a cluster in the neighbour-joining phylogenetic tree. In the maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences and the phylogenetic tress based on gyrB sequences, strain OITF-57^T formed evolutionary lineages independent of those of other taxa. Strain OITF-57^T contained Q-10 as the predominant ubiquinone and C_18:1 ω7c as the major fatty acid. The major polar lipids of strain OITF-57^T were phosphatidylcholine and phosphatidylglycerol. The DNA G + C content of strain OITF-57^T was 66.0 mol%. The chemotaxonomic data and other differential phenotypic properties made it possible to distinguish strain OITF-57^T from the genus Pontivivens and other phylogenetically related genera. On the basis of the data presented, strain OITF-57^T constitutes a new genus and species within the class Alphaproteobacteria, for which the name Pseudopontivivens aestuariicola gen. nov., sp. nov. is proposed. The type strain is OITF-57^T (= KACC 19570^T = CGMCC 1.13481^T).

Rhodosalinus sediminis gen. nov., sp. nov., isolated from marine saltern

A novel Gram-stain-negative, moderately halophilic, motile, facultatively anaerobic and rod-shaped strain, designated WDN1C137^T, was isolated from a marine saltern at Wendeng, PR China. Optimal growth occurred at 40 °C, pH 7.5 and with 7.0 % (w/v) NaCl. Q-10 was the sole respiratory quinone. The major cellular fatty acids (>10.0 %) in WDN1C137^T were C18 : 1ω7c (46.2 %), cyclo C19 : 0ω8c (18.7 %) and C16 : 0 (12.3 %). The major polar lipids were phosphatidylglycerol, phosphoglycolipid, phosphatidylcholine, one unidentified glycolipid, one unidentified lipid, one unidentified aminolipid and two unidentified phospholipids. The genomic DNA G+C content was 70.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that WDN1C137^T shared the highest similarity (94.5 %) to Roseivivax jejudonensis KCTC 42110^T, followed by Roseivivax halodurans JCM 10272^T (94.2 %) and Roseivivax roseus DSM 23042^T (94.1 %). WDN1C137^T formed a separate branch from the closely related genera Roseivivax, Loktanella, Paracoccus and Cribrihabitans within the family Rhodobacteraceae, which indicated that it represented a novel genus in the phylogenetic tree. On the basis of the data from the current polyphasic study, the isolate is proposed to represent a novel species of a novel genus within the family Rhodobacteraceae, with the name Rhodosalinus sediminis gen. nov., sp. nov. The type strain of the type species is WDN1C137^T (=KCTC 52478^T=MCCC 1H00170^T).

Psychromarinibacter halotolerans gen. nov., sp. nov., isolated from seawater of the Yellow Sea

A Gram-stain-negative, strictly aerobic, motile, non-gliding, oxidase-positive, catalase-positive, rod-shaped bacterium, designated strain YBW34T, was isolated from seawater from the bottom of the Yellow Sea at station H12 (-73m in depth). Growth occurred at 10-45 °C (optimum 28 °C), in the presence of 1-12 % NaCl (w/v, optimum 4 %) and at pH 6.0-8.0 (optimum pH 7.0). The major fatty acids (>10 %) were C18 : 1 ω7c and C16 : 0. The major polar lipids comprised phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine and three unidentified aminolipids. The major respiratory quinone was ubiquinone-10 (Q-10). The DNA G+C content of strain YBW34T was 64.2 mol%. The most closely related species was Tropicimonas isoalkanivorans JCM 14837T with 95.8 % sequence similarity in Alphaproteobacteria. It showed 16S rRNA gene sequence similarities of 93.03-95.49, 93.03-95.49 and 95.31-95.32 % to species of genera Rhodovulum, Lutimaribacter and Oceanicola, respectively. Nevertheless, strain YBW34T formed a distinct lineage in the trees which did not join the genera mentioned above in the phylogenetic dendrogram based on 16S rRNA gene sequences. The phenotypic, chemotaxonomic and phylogenetic data indicated that strain YBW34T represents a novel genus and species, for which the name Psychromarinibacter halotolerans gen. nov., sp. nov. is proposed. The type strain is YBW34T (=JCM 31462T=KCTC 52366T=MCCC 1K03203T).

Amylibacter cionae sp. nov., isolated from the sea squirt Ciona savignyi

A Gram-stain-negative, non-motile, aerobic and rod-shaped bacterial strain, designated H-12T, was isolated from a sea squirt (Ciona savignyi) collected from Tsingtao Port, Jiaozhou Bay, China, and its taxonomic position was investigated. Strain H-12T grew optimally at 25-30 °C, at pH 7.0-8.0 and in the presence of 3.0-4.0 % (w/v) NaCl. The 16S rRNA gene sequence of strain H-12T exhibited the highest similarity to that of the type strain of Amylibacter marinus (95.3 %). A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain H-12T clustered with the type strain of A. marinus. The predominant ubiquinone in strain H-12T was identified as Q-10. The major fatty acids of strain H-12T were C18 : 1ω7c and C18 : 1ω7c 11-methyl. The major polar lipids detected in strain H-12T were phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, one unidentified aminolipid, two unidentified phospholipids and five unidentified lipids. The DNA G+C content of strain H-12T was 52.7 mol%. On the basis of phylogenetic, chemotaxonomic and phenotypic properties, strain H-12T is considered to represent a novel species within the genus Amylibacter, for which the name Amylibacter cionae sp. nov. is proposed. The type strain is H-12T (=KCTC 52581T=CGMCC 1.15880T).