Paracoccus broussonetiae subsp. drimophilus subsp. nov., a Novel Subspecies Salt-Tolerant Endophytic Bacterium from Maize Root in Hunan

In an investigation exploring endophytic microbiota from agricultural crops, an aerobic, non-motile, Gram-negative, coccobacillus-shaped bacterial isolate, designated as strain NGMCC 1.201697T, was isolated from maize roots in Hunan Province, China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain NGMCC 1.201697T belonged to the genus Paracoccus, showing the highest sequence similarity to Paracoccus broussonetiae CPCC 101403T (99.86%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) were 98.57% and 87.90% between the novel isolate and its closest phylogenetic relative. However, phenotypic characterization further differentiated the isolate from P. broussonetiae CPCC 101403T. The isolate showed enhanced environmental tolerance adaptability (growth in 0-8% NaCl and 4-37 °C), unique enzymatic activities (esterase C4, β-glucosidase, L-proline arylamidase, and β-galactosidase), and expanded metabolic capabilities (D-mannitol, D-cellobiose, saccharose, and so on). The major polar lipids consisted of diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylglycerol (PG), two unidentified glycolipids (GLs) and four unidentified phospholipids (PLs). The predominant respiratory quinone was ubiquinone-10, and the major fatty acid was summed feature 8 (C18:1 ω7c, 69.42%). The DNA G + C content was 64.49 mol%. Based on results of these analyses, strain NGMCC 1.201697T represents a novel subspecies of Paracoccus broussonetiae, for which the name Paracoccus broussonetiae subsp. drimophilus subsp. nov. is proposed. The type-strain is NGMCC 1.201697T (=CGMCC 1.61958T =JCM 37104T).

Paracoccus actinidiae sp.nov., a novel bacterium isolated from kiwi tree rhizosphere soil

Strain M09T was isolated from the rhizoshere of kiwi fruit trees from an orchard located in Fangshan, Beijing, PR China (39° 49' 25.1″ N, 116° 4' 44.5″ E,). It is a short rod-shaped, Gram-stain-negative, facultatively anaerobic bacterium that tests positive for both oxidase and catalase. The strain exhibited growth within the temperature range of 15-45 °C (optimal growth at 30 °C) and the pH range of 4.0-10.0 (optimal growth at pH 7.0) and without NaCl. It also grew in a sodium chloride-free nutrient agar (NA) medium. The results of phylogenetic analysis of the 16S rRNA gene sequences indicated that M09T represents a member of the genus Paracoccus and shares high similarity with Paracoccus everestensis S8-55T (98.46%) and Paracoccus aerius 011410T (97.58%). The average nucleotide identity values between M09T and P. everestensis S8-55T, P. aerius 011410T, Paracoccus marinaquae X HP0099T and Paracoccus fontiphilus MVW-1T were 95.56, 84.51, 79.83 and 83.68%, respectively. The digital DNA-DNA hybridisation values between between M09T and P. everestensis S8-55T, P. aerius 011410T, P. marinaquae X HP0099T and P. fontiphilus MVW-1T were 56.40, 29.30, 21.60 and 28.60%, respectively. The major fatty acids identified were C10 : 0 3-OH (51.8%) and C18 : 1ω7c (35.5%). The major respiratory quinone was Q-10, with Q-8 present as a minor component. Polar lipids were mainly comprised of diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylcholine (PC), and phosphatidylethanolamine (PE). Genome sequencing revealed that the strain has a DNA G+C content of 64.31 mol%. On the basis of this comprehensive taxonomic characterisation data, M09T represents a novel species within the genus Paracoccus and has been named Paracoccus actinidiae sp. nov. The type strain is designated as M09T (=GDMCC 1.4157T=KCTC 8143T).

Paracoccus benzoatiresistens sp. nov., a benzoate resistance and selenite reduction bacterium isolated from wetland

A Gram-stain-negative, aerobic, non-motile, catalase- and oxidase-positive, pale orange, rod-shaped strain EF6T, was isolated from a natural wetland reserve in Hebei province, China. The strain grew at 25-37 °C (optimum, 30 °C), pH 5-9 (optimum, pH 7), and in the presence of 1.0-4.0% (w/v) NaCl (optimum, 2%). A phylogenetic analysis based on 16S rRNA gene sequence revealed that strain EF6T belongs to the genus Paracoccus, and the closest members were Paracoccus shandongensis wg2T with 98.1% similarity, Paracoccus fontiphilus MVW-1 T (97.9%), Paracoccus everestensis S8-55 T (97.7%), Paracoccus subflavus GY0581T (97.6%), Paracoccus sediminis CMB17T (97.3%), Paracoccus caeni MJ17T (97.0%), and Paracoccus angustae E6T (97.0%). The genome size of strain EF6T was 4.88 Mb, and the DNA G + C content was 65.3%. The digital DNA-DNA hybridization, average nucleotide identity, and average amino acid identity values between strain EF6T and the reference strains were all below the threshold limit for species delineation (< 32.8%, < 88.0%, and < 86.7%, respectively). The major fatty acids (≥ 5.0%) were summed feature 8 (86.3%, C18:1 ω6c and/or C18:1 ω7c) and C18:1 (5.0%) and the only isoprenoid quinone was Q-10. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, two unidentified glycolipids, five unidentified phospholipids, and an unidentified aminolipid. Strain EF6T displays notable resistance to benzoate and selenite, with higher tolerance levels (25 g/L for benzoate and 150 mM for selenite) compared to the closely related species. Genomic analysis identified six benzoate resistance genes (acdA, pcaF, fadA, pcaC, purB, and catA) and twenty selenite resistance and reduction-related genes (iscR, ssuB, ssuD, selA, selD and so on). Additionally, EF6T possesses unique genes (catA, ssuB, and ssuC) absent in the closely related species for benzoate and selenite resistance. Its robust resistance to benzoate and selenite, coupled with its genomic makeup, make EF6T a promising candidate for the remediation of both organic and inorganic pollutants. It is worth noting that the specific resistance phenotypes described above were not reported in other novel species in Paracoccus. Based on the results of biochemical, physiological, phylogenetic, and chemotaxonomic analyses, combined with comparisons of the 16S rRNA gene sequence and the whole genome sequence, strain EF6T is considered to represent a novel species of the genus Paracoccus within the family Rhodobacteraceae, for which the name Paracoccus benzoatiresistens sp. nov. is proposed. The type strain is EF6T (= GDMCC 1.3400 T = JCM 35642 T = MCCC 1K08702T).

Metabolomic and genomic insights into TMA degradation by a novel halotolerant strain - Paracoccus sp. PS1

Trimethylamine N-oxide (TMAO) is a gut metabolite that acts as a biomarker for chronic diseases, and is generated by the oxidation of trimethylamine (TMA) produced by gut microflora. Since, microbial degradation of TMA is predicted to be used to restrict the production of TMAO, we aimed to isolate bacterial strains that could effectively degrade TMA before being oxidized to TMAO. As marine fish is considered to have a rich content of TMAO, we have isolated TMA degrading isolates from fish skin. Out of the fourteen isolates, depending on their rapid TMA utilization capability in mineral salt medium supplemented with TMA as a sole carbon and nitrogen source, isolate PS1 was selected as our desired isolate. Its TMA degrading capacity was further confirmed through spectrophotometric, Electrospray Ionization Time-of-Flight Mass Spectrometry (ESI TOF-MS) and High performance liquid chromatography (HPLC) analysis and in silico analysis of whole genome (WG) gave further insights of protein into its TMA degradation pathways. PS1 was taxonomically identified as Paracoccus sp. based on its 16S rRNA and whole genome sequence analysis. As PS1 possesses the enzymes required for degradation of TMA, clinical use of this isolate has the potential to reduce TMAO generation in the human gut.

Paracoccus onchidii sp. nov., a moderately halophilic bacterium isolated from a marine invertebrate from the South China Sea

A novel moderately halophilic bacterial strain, designated Z330^T, was isolated from the egg of a marine invertebrate of the genus Onchidium collected in the South China Sea. The 16S rRNA gene sequence of strain Z330^T exhibited the highest similarity value to that of the type strain Paracoccus fistulariae KCTC 22803^T (97.6%), Paracoccus seriniphilus NBRC 100798^T (97.6%) and Paracoccus aestuarii DSM 19484^T (97.6%). Phylogenomic and 16S rRNA phylogenetic analysis showed that strain Z330^T was most closely related to P. seriniphilus NBRC 100798^T and P. fistulariae KCTC 22803^T. Strain Z330^T grew optimally at 28-30 °C, pH 7.0-8.0 with the presence of 5.0-7.0% (w/v) NaCl. In addition, growth of strain Z330^T occurred at 0.5-16% NaCl, indicated strain Z330^T was a moderately halophilic and halotolerant bacterium of genus Paracoccus. The predominant respiratory quinone in strain Z330^T was identified as ubiquinone-10. The major polar lipids of strain Z330^T were phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, glycolipid and six unidentified polar lipids. The major fatty acids of strain Z330^T was summed feature 8 (C_18:1 ω6c and/or C_18:1 ω7c). The draft genome sequence of strain Z330^T includes 4,084,570 bp in total (N50 = 174,985 bp) with a medium read coverage of 463.6 × and 83 scaffolds. The DNA G + C content of strain Z330^T was 60.5%. In silico DNA-DNA hybridization with the four type strains showed 20.5, 22.3, 20.1 and 20.1% relatedness to Paracoccus fistulariae KCTC 22803^T, Paracoccus seriniphilus NBRC 100798^T, Paracoccus aestuarii DSM 19484^T and Paracoccus denitrificans 1A10901^T, respectively. And the average nucleotide identity (ANIb) values between strain Z330^T and these four type strains were 76.2, 80.0, 75.8 and 73.8%, respectively, lower than the 95-96% threshold value for dividing prokaryotic species. On the basis of the phenotypic, phylogenetic, phylogenomic and chemotaxonomic properties, a novel species of the genus Paracoccus, Paracoccus onchidii sp. nov. is proposed with the type strain Z330^T (= KCTC 92727^T = MCCC 1K08325^T).

Insights into carbon-fixation pathways through metagonomics in the sediments of deep-sea cold seeps

Carbon fixation by chemoautotrophic microorganisms in the dark ocean has a major impact on global carbon cycling and ecological relationships in the ocean's interior. At present, six pathways of autotrophic carbon fixation have been found: the Calvin cycle, the reductive Acetyl-CoA or Wood-Ljungdahl pathway (rAcCoA), the reductive tricarboxylic acid cycle (rTCA), the 3-hydroxypropionate bicycle (3HP), the 3-hydroxypropionate/4-hydroxybutyrate cycle (3HP/4HB), and the dicarboxylate/4-hydroxybutyrate cycle (DC/4HB). Although our knowledge about carbon fixation pathways in the ocean has increased significantly, carbon fixation pathways in the cold seeps are still unknown. In this study, we collected sediment samples from two cold seeps and one trough in the south China sea (SCS), and investigated with metagenomic and metagenome assembled genomes (MAGs). We found that six autotrophic carbon fixation pathways present in the cold seeps and trough with rTCA cycle was the most common pathway, whose genes were particularly high in the cold seeps and increased with sediment depths; the rAcCoA cycle mainly occurred in the cold seep regions, and the abundance of module genes increased with sediment depths. We also elucidated members of chemoautotrophic microorganisms involved in these six carbon-fixation pathways. The rAcCoA, rTCA and DC/4-HB cycles required significantly less energy probably play an important role in the deep-sea environments, especially in the cold seeps. This study provided metabolic insights into the carbon fixation pathways in the cold seeps, and laid the foundation for future detailed study on processes and rates of carbon fixation in the deep-sea ecosystems.

Agromyces kandeliae sp. nov., isolated from rhizosphere soil of Kandelia candel in a mangrove

A novel, Gram-stain-positive, aerobic, non-spore-forming, non-motile and irregular rod-shaped bacterium designated Q22^T was isolated from the rhizosphere soil of mangrove plant, Kandelia candel collected in Zhangzhou, Fujian province, China. Strain Q22^T was able to grow at 10-40 °C (optimum 30 °C), pH 5.5-9.0 (optimum 7.0-8.0) and with 0-5.0% (w/v) NaCl (optimum 1.0 %). The genomic DNA G+C content was 71.9%. The average nucleotide identity, and in silico DNA-DNA hybridization values between strain Q22^T and the reference strains were 79.7-88.9% and 22.6-37.4%, respectively. The predominant isoprenoid quinone was MK-12 and the major fatty acids were anteiso-C_15:0, iso-C_16:0 and anteiso-C_17:0. The major polar lipids of strain Q22^T were diphosphatidylglycerol, phosphatidylglycerol, one glycolipid and three unidentified lipids. The strain Q22^T contained 2,4-diaminobutyric acid, alanine acid, glutamic acid and glycine in the peptidoglycans. The phylogenetic analysis and genotypic features, along with the phenotypic and chemotaxonomic characteristics, indicate that strain Q22^T represents a novel species of the genus Agromyces, for which the name Agromyces kandeliae sp. nov. is proposed. The type strain is Q22^T (=MCCC 1K03340^T= KCTC 39961^T).

Croceivirga litoralis sp. nov., isolated from coastal surface water, and reclassification of Muricauda lutea as Croceivirga lutea comb. nov

A novel Gram-stain-negative, aerobic, yellow-pigmented bacterium was isolated from seawater of Aoshan Bay, and designated as strain ASW18^T. Strain ASW18^T was a long-rod-shaped bacterium without flagellum and lacked gliding ability. Based on 16S rRNA gene phylogeny, strain ASW18^T showed the closest relationship to Croceivirga radicis MCCC 1A06690^T, with a sequence similarity of 97.0 %. Strain ASW18^T was able to grow at 25-40 °C, at pH 5.5-9.5 and with 0.5-9 % (w/v) NaCl. The genomic DNA G+C content of strain ASW18^T was 37.3 %. The predominant cellular fatty acids of strain ASW18^T were iso-C_15 : 0, iso-C_17 : 0 3-OH and iso-C_15 : 1 G. The major polar lipids were phosphatidylethanolamine, phosphatidyldimethylethanolamine, an aminolipid and three unidentified lipids. The respiratory quinone of strain ASW18^T was menaquinone with six isoprene units (MK-6). Based on the present polyphasic analysis, strain ASW18^T represents a novel species of the genus Croceivirga, for which the name Croceivirga litoralis sp. nov. is proposed; the type strain is ASW18^T (=MCCC 1K04203^T=KCTC 72852^T). In addition, it is also proposed that Muricauda lutea should be reclassified as Croceivirga lutea comb. nov.; the type strain is CSW06^T (=CGMCC 1.15761^T=JCM 31455^T=KCTC 52375^T=MCCC 1K03195^T).

Nesterenkonia muleiensis sp. nov., a novel actinobacterium isolated from sap of Populus euphratica

A novel, Gram-stain-positive, aerobic, non-endospore-forming, non-motile and rod-shaped bacterium designated RB2^T was isolated from sap of Populus euphratica collected in Mulei county, Xinjiang province, PR China. RB2^T was able to grow at 10-45 °C (optimum 35 °C), pH 6.0-12.0 (optimum 8.0) and with 0-12 % (w/v) NaCl (optimum 1 %). The genomic DNA G+C content was 63.5 % (from the genome sequence). The results of the chemotaxonomic analysis indicated that the predominant isoprenoid quinones were MK-8 and MK-9. The major fatty acids were anteiso-C_15 : 0 and anteiso-C_17 : 0. The major polar lipids of RB2^T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and two glycolipids. The peptidoglycan type of RB2^T was A4α, l-Lys-Gly-l-Glu. The results of the phylogenetic analysis, along with the phenotypic and chemotaxonomic characteristics, indicate that strain RB2^T represents a novel species of the genus Nesterenkonia, for which the name Nesterenkonia muleiensis sp. nov. is proposed. The type strain is RB2^T (=MCCC 1K03528^T=KCTC 49017^T).

Analysis of 1,000+ Type-Strain Genomes Substantially Improves Taxonomic Classification of Alphaproteobacteria

The class Alphaproteobacteria is comprised of a diverse assemblage of Gram-negative bacteria that includes organisms of varying morphologies, physiologies and habitat preferences many of which are of clinical and ecological importance. Alphaproteobacteria classification has proved to be difficult, not least when taxonomic decisions rested heavily on a limited number of phenotypic features and interpretation of poorly resolved 16S rRNA gene trees. Despite progress in recent years regarding the classification of bacteria assigned to the class, there remains a need to further clarify taxonomic relationships. Here, draft genome sequences of a collection of genomes of more than 1000 Alphaproteobacteria and outgroup type strains were used to infer phylogenetic trees from genome-scale data using the principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families and genera, including taxa recognized as problematic long ago but also quite recent taxa, as well as a few species were shown to be in need of revision. According proposals are made for the recognition of new orders, families and genera, as well as the transfer of a variety of species to other genera and of a variety of genera to other families. In addition, emended descriptions are given for many species mainly involving information on DNA G+C content and (approximate) genome size, both of which are confirmed as valuable taxonomic markers. Similarly, analysis of the gene content was shown to provide valuable taxonomic insights in the class. Significant incongruities between 16S rRNA gene and whole genome trees were not found in the class. The incongruities that became obvious when comparing the results of the present study with existing classifications appeared to be caused mainly by insufficiently resolved 16S rRNA gene trees or incomplete taxon sampling. Another probable cause of misclassifications in the past is the partially low overall fit of phenotypic characters to the sequence-based tree. Even though a significant degree of phylogenetic conservation was detected in all characters investigated, the overall fit to the tree varied considerably.

Paracoccus aeridis sp. nov., an indole-producing bacterium isolated from the rhizosphere of an orchid, Aerides maculosa

A Gram-stain-negative, non-motile, coccoid-shaped, catalase- and oxidase-positive, non-denitrifying, neutrophilic bacterium designated as strain JC501T was isolated from an epiphytic rhizosphere of an orchid, Aerides maculosa, growing in the Western Ghats of India. Phylogenetic analyses based on the 16S rRNA gene sequence indicated that strain JC501T belonged to the genus Paracoccus and had the highest levels of sequence identity with Paracoccus marinus KKL-A5T (98.9 %), Paracoccus contaminans WPAn02T (97.3 %) and other members of the genus Paracoccus (<97.3 %). Strain JC501T produced indole-3 acetic acid and other indole derivatives from tryptophan. The dominant respiratory quinone was Q-10 and the major fatty acid was C18 : 1ω7c/C18 : 1ω6c, with significant quantities of C18 : 1ω9c, C17 : 0 and C16 : 0. The polar lipids of strain JC501T comprised phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, an unidentified glycolipid, two unidentified aminolipids, two unidentified lipids and four unidentified phospholipids. The genome of strain JC501T was 3.3 Mbp with G+C content of 69.4 mol%. For the resolution of the phylogenetic congruence of the novel strain, the phylogeny was also reconstructed with the sequences of eight housekeeping genes. Based on the results of phylogenetic analyses, low (<85.9 %) average nucleotide identity, digital DNA–DNA hybridization (<29.8 %), chemotaxonomic analysis and physiological properties, strain JC501T could not be classified into any of the recognized species of the genus Paracoccus . Strain JC501T represents a novel species, for which the name Paracoccus aeridis sp. nov. is proposed. The type strain is JC501T (=LMG 30532T=NBRC 113644T).

Taxogenomics Resolves Conflict in the Genus Rhodobacter: A Two and Half Decades Pending Thought to Reclassify the Genus Rhodobacter

The genus Rhodobacter is taxonomically well studied, and some members are model organisms. However, this genus is comprised of a heterogeneous group of members. 16S rRNA gene-based phylogeny of the genus Rhodobacter indicates a motley assemblage of anoxygenic phototrophic bacteria (genus Rhodobacter) with interspersing members of other genera (chemotrophs) making the genus polyphyletic. Taxogenomics was performed to resolve the taxonomic conflicts of the genus Rhodobacter using twelve type strains. The phylogenomic analysis showed that Rhodobacter spp. can be grouped into four monophyletic clusters with interspersing chemotrophs. Genomic indices (ANI and dDDH) confirmed that all the current species are well defined, except Rhodobacter megalophilus. The average amino acid identity values between the monophyletic clusters of Rhodobacter members, as well as with the chemotrophic genera, are less than 80% whereas the percentage of conserved proteins values were below 70%, which has been observed among several genera related to Rhodobacter. The pan-genome analysis has shown that there are only 1239 core genes shared between the 12 species of the genus Rhodobacter. The polyphasic taxonomic analysis supports the phylogenomic and genomic studies in distinguishing the four Rhodobacter clusters. Each cluster is comprised of one to seven species according to the current Rhodobacter taxonomy. Therefore, to address this taxonomic discrepancy we propose to reclassify the members of the genus Rhodobacter into three new genera, Luteovulum gen. nov., Phaeovulum gen. nov. and Fuscovulum gen. nov., and provide an emended description of the genus Rhodobacter sensu stricto. Also, we propose reclassification of Rhodobacter megalophilus as a sub-species of Rhodobacter sphaeroides.

Paracoccus sediminilitoris sp. nov., isolated from a tidal flat sediment

A novel marine Gram-stain-negative, non-spore-forming, motile, aerobic, coccoid or ovoid bacterium, designated as strain DSL-16T, was isolated from a tidal flat sediment on the East China Sea and characterized phylogenetically and phenotypically. Optimal growth of the strain occurred at 35 °C (range 4–40 °C), at pH 6 (range 5–11) and with 4 % (w/v) NaCl (range 1–14 %). The nearest phylogenetic neighbour was Paracoccus seriniphilus DSM 14827T (98.2 % 16S rRNA gene sequence similarity). The digital DNA–DNA hybridization value between strain DSL-16T and P. seriniphilus DSM 14827T was 19.5±2.2 %. The average nucleotide identity value between strain DSL-16T and P. seriniphilus DSM 14827T was 83.6 %. The sole respiratory ubiquinone was Q-10. The major polar lipids were phosphatidylmonomethylethanolamine (PME), phosphatidylglycerol (PG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), diphosphatidyglycerol (DPG) and glycolipid (GL). The predominant cellular fatty acids of strain DSL-16T were C18 : 1ω7c, C18 : 0 and 11-methyl C18 : 1ω7c. The G+C content of the genomic DNA was 64.5 mol%. The combined genotypic and phenotypic data indicated that strain DSL-16T represents a novel species of the genus Paracoccus , for which the name Paracoccus sediminilitoris sp. nov. is proposed. The type strain is DSL-16T (=KCTC 62644T=MCCC 1K03534T).

Associated bacteria of Botryococcus braunii (Chlorophyta)

Botryococcus braunii (Chlorophyta) is a green microalga known for producing hydrocarbons and exopolysaccharides (EPS). Improving the biomass productivity of B. braunii and hence, the productivity of the hydrocarbons and of the EPS, will make B. braunii more attractive for industries. Microalgae usually cohabit with bacteria which leads to the formation of species-specific communities with environmental and biological advantages. Bacteria have been found and identified with a few B. braunii strains, but little is known about the bacterial community across the different strains. A better knowledge of the bacterial community of B. braunii will help to optimize the biomass productivity, hydrocarbons, and EPS accumulation. To better understand the bacterial community diversity of B. braunii, we screened 12 strains from culture collections. Using 16S rRNA gene analysis by MiSeq we described the bacterial diversity across 12 B. braunii strains and identified possible shared communities. We found three bacterial families common to all strains: Rhizobiaceae, Bradyrhizobiaceae, and Comamonadaceae. Additionally, the results also suggest that each strain has its own specific bacteria that may be the result of long-term isolated culture.

Marortus luteolus gen. nov., sp. nov., isolated from surface seawater of the East Sea in China

A Gram-stain-negative, motile, aerobic, rod-shaped bacterium with flagella, designated ZX-21^T, was isolated from surface seawater of the East Sea in Zhoushan, China. Growth of strain ZX-21T was observed at 10--35  o°C (optimum, 30 °C), at pH 6.0-8.5 (pHoptimum 6.5-7.0) and in the presence of 0.5-8 % (w/v) NaCl (optimum 3-4 %). It was positive for oxidase and catalase activity. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain ZX-21T constituted an independent lineage within the family Spongiibacteraceae and was most closely related to Zhongshania guokunii (96.83 %). Strain ZX-21T contained ubiquinone-8 (Q-8) as the sole isoprenoid quinone and summed feature 3 (C16 : 1ω77c and/or C16 : 1ω66c), summed feature 8 (C18 : 1ω77c and/or C18 : 1ω66c) and C16 : 0 as the major fatty acids. Phosphatidylglycerol (), phosphatidylethanolamine (), diphosphatidylglycerol () and an unidentified glycolipid were the major cellular polar lipids. The DNA G+C content was 49.1 mol%. Based on itsthe morphological, physiological and chemotaxonomic characteristics, strain ZX-21Tis described as a novel species in a novel genus for whichwith the name Marortus luteolus gen. nov., sp. nov. (type strain ZX-21T = MCCC 1K03431T=KCTC 62160T) is proposed.

Minwuia thermotolerans gen. nov., sp. nov., a marine bacterium forming a deep branch in the Alphaproteobacteria, and proposal of Minwuiaceae fam. nov. and Minwuiales ord. nov

Two Gram-stain-negative, strictly aerobic, non-motile, non-spore-forming, rod-shaped bacteria, designated as SY3-15^Tand SY3-13, were isolated from a seawater sample of the South China Sea. Colonies were 0.5-1.0 mm in diameter, smooth, circular, convex and translucent after growth on marine agar at 37 °C for 3 days. The strains were found to grow at 20-50 °C (optimum, 42 °C), pH 6.0-8.5 (optimum, pH 6.5-7.5) and with 0.5-6.0 % (w/v) NaCl (optimum, 1.5-2.0 %). Chemotaxonomic analysis showed the sole respiratory quinone to be ubiquinone-10, the major fatty acids (>10 %) were C16 : 0 3-OH, C19 : 0cyclo ω9c, C18 : 1 3-OH and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), and the polar lipids were phosphatidylglycerol, two unidentified aminolipids and three unidentified lipids. The DNA G+C content was 67.2-67.4 mol% calculated by genome. The 16S rRNA gene sequences of strains SY3-15^T and SY3-13 were identical and related to the genus Lutibaculum with a similarity of 92.1 %. The 16S rRNA gene phylogenetic trees reconstructed with neighbour-joining, maximum-parsimony and minimum-evolution methods showed that the strains constituted a deep and separated branch from other families of Alphaproteobacteria, and the phylogenetic trees based on concatenated 163 protein sequences from genome sequences showed that the clade in which strains SY3-15^T and SY3-13 located was separated from the clade of the other orders of Alphaproteobacteria, indicating it may represent a novel family of a novel order. Based on their phenotypic properties and their phylogenetic distinctiveness, we propose strains SY3-15^T (=MCCC 1K03467^T=KCTC 62335^T) and SY3-13 (=MCCC 1K03466=KCTC 62329) to represent a novel species of a novel genus with the name Minwuia thermotolerans gen. nov., sp. nov., and we propose Minwuiaceae fam. nov. and Minwuiales ord. nov. with Minwuia as the type genus.

Confluentibacter flavum sp. nov., Isolated from the Saline Lake

A Gram-stain-negative, rod-shaped, non-motile, bacterial isolate designated 3B^T, was isolated from a saline lake, and subjected to a polyphasic taxonomic investigation. The phylogenetic analysis based on 16S rRNA gene sequence clearly showed an allocation to the genus Confluentibacter with similarity ranging from 95.1 to 98%. OrthoANI values between strain 3B^T and related strains of Confluentibacter (< 90%) were lower than the threshold value of 95% ANI relatedness recommended for species demarcation. Strain 3B^T grew at 4-35 °C and pH 6.0-8.0 (optimum, 28 °C and pH 6.5) and with 0-3% (w/v) NaCl (optimum, 0.5%). The predominant respiratory quinone was menaquinone-6 (MK-6) and the major fatty acids were iso-C_15:0, iso-C_15:1 G, iso-C_15:0 3-OH, and iso-C_17:0 3-OH. The polar lipid profile of strain 3B^T comprised phosphatidylethanolamine, one unidentified aminolipid, one aminophospholipid, and three unidentified lipids (L1-3). The DNA G+C content was 33.1 mol%. On the basis of morphological, physiological, and chemotaxonomic characteristics, together with the results of phylogenetic analysis, strain 3B^T is described as a novel species in genus Confluentibacter, for which the name Confluentibacter flavum sp. nov. (type strain 3B^T = CGMCC115960^T = KCTC52969^T) is proposed.

Paracoccus fontiphilus sp. nov., isolated from a freshwater spring

Strain MVW-1^T, isolated from a freshwater spring in Taiwan, was characterized by using a polyphasic taxonomy approach. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain MVW-1^T belongs to the genus Paracoccus and has the highest levels of sequence similarity to Paracoccus caeni MJ17^T (97.6 %), Paracoccus sediminis CMB17^T (97.4 %), Paracoccus angustae E6^T (97.3 %) and Paracoccus acridae SCU-M53^T (97.1 %). Cells were Gram-stain-negative, aerobic, poly-β-hydroxybutyrate-accumulating, non-motile, rod-shaped and formed light orange-coloured colonies. Optimal growth occurred at 20-25 °C, pH 6-7, and in the presence of 0-3 % NaCl. The major fatty acid of strain MVW-1^T was C18 : 1ω7c. The polar lipid profile consisted of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, diphosphatidylglycerol, an unidentified glycolipid, an unidentified aminolipid and three unidentified phospholipids. The predominant polyamines were spermidine, putrescine and cadaverine. The only isoprenoid quinone was Q-10. The genomic DNA G+C content of strain MVW-1^T was 63.4 mol%. Strain MVW-1^T exhibited less than 35 % DNA-DNA relatedness to P. caeni MJ17^T, P. angustae E6^T, P. sediminis CMB17^T and P. acridae SCU-M53^T. On the basis of phenotypic and genotypic properties and phylogenetic inference, strain MVW-1^T should be classified in a novel species of the genus Paracoccus, for which the name Paracoccus fontiphilus sp. nov. is proposed. The type strain is MVW-1^T (=BCRC 80974^T=LMG 29554^T=KCTC 52239^T).

Kordiimonas pumila sp. nov., isolated from coastal sediment

A novel Gram-stain-negative, translucent-white, aerobic, motile and rod-shaped strain, designated N18^T, was isolated from a coastal sediment sample collected in Zhoushan, Zhejiang Province, China. 16S rRNA gene similarity analysis revealed that strain N18^T demonstrated highest similarity to the genus Kordiimonas(95.3-97.2 %). Phylogenetic analysis of 16S rRNA gene sequence showed that strain N18^T represented a distinct lineage in the clade consisting of the genus Kordiimonas. Strain N18^T was found to grow at 10-37 °C (optimum 28 °C), pH 6.0-8.0 (optimum 7.0) and with 1.0-4.0 % (w/v) NaCl (optimum 2.5 %). The G+C content of the genomic DNA was 55.3 mol%. The major cellular fatty acids were identified as summed feature 3 (comprising iso-C15 : 0 2-OH/C16 : 1ω7c), iso-C17 : 1ω9c and iso-C15 : 0. The polar lipid profile of N18^T consisted of phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, an unidentified glycolipid, an unidentified aminoglycolipid, an unidentified aminophospholipid and five unidentified lipids. The respiratory quinone was Q-10. Based on chemotaxonomic, morphological and physiological properties, strain N18^T could be distinguished from its closest phylogenetic neighbours. Thus, we propose Kordiimonas pumila sp. nov., the type strain is N18^T (=MCCC 1K03436^T=KCTC 62164^T).

Bacterial Diversity and Biogeochemistry of Two Marine Shallow-Water Hydrothermal Systems off Dominica (Lesser Antilles)

Shallow-water hydrothermal systems represent extreme environments with unique biogeochemistry and high biological productivity, at which autotrophic microorganisms use both light and chemical energy for the production of biomass. Microbial communities of these ecosystems are metabolically diverse and possess the capacity to transform a large range of chemical compounds. Yet, little is known about their diversity or factors shaping their structure or how they compare to coastal sediments not impacted by hydrothermalism. To this end, we have used automated ribosomal intergenic spacer analysis (ARISA) and high-throughput Illumina sequencing combined with porewater geochemical analysis to investigate microbial communities along geochemical gradients in two shallow-water hydrothermal systems off the island of Dominica (Lesser Antilles). At both sites, venting of hydrothermal fluids substantially altered the porewater geochemistry by enriching it with silica, iron and dissolved inorganic carbon, resulting in island-like habitats with distinct biogeochemistry. The magnitude of fluid flow and difference in sediment grain size, which impedes mixing of the fluids with seawater, were correlated with the observed differences in the porewater geochemistry between the two sites. Concomitantly, individual sites harbored microbial communities with a significantly different community structure. These differences could be statistically linked to variations in the porewater geochemistry and the hydrothermal fluids. The two shallow-water hydrothermal systems of Dominica harbored bacterial communities with high taxonomical and metabolic diversity, predominated by heterotrophic microorganisms associated with the Gammaproteobacterial genera Pseudomonas and Pseudoalteromonas, indicating the importance of heterotrophic processes. Overall, this study shows that shallow-water hydrothermal systems contribute substantially to the biogeochemical heterogeneity and bacterial diversity of coastal sediments.

Aestuarium zhoushanense gen. nov., sp. nov., Isolated from the Tidal Flat

A gram-stain-negative, aerobic, ovoid or short rod-shaped, and non-motile strain, designed G7^T was isolated from a tidal flat sample collected from the coast of East Sea in Zhoushan, China. Strain G7^T grew at 4-40 °C and pH 6.0-9.0 (optimum, 28 °C and pH 7.5) and with 0-7% (w/v) NaCl (optimum, 1%). The predominant respiratory quinone was Q-10 and the major fatty acids (>10%) identified were C_18:1 ω7c, C_16:0 and summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c). The polar lipids of strain G7^T consisted of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, and four unidentified lipids. The genomic DNA G+C content was 56.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain G7^T formed a distinct lineage belonging to the Roseobacter clade of the family Rhodobacteraceae. On the basis of morphological, physiological, and chemotaxonomic characteristics, together with the results of phylogenetic analysis, strain G7^T is described as a novel species in a new genus, for which the name Aestuarium zhoushanense gen. nov., sp. nov. (type strain G7^T = MCCC 1K03229^T = KCTC 52584^T) is proposed.

Paracoccus aerius sp. nov., isolated from air

Strain 011410T, isolated from air at the foot of Xiangshan Mountain, Beijing, China, was Gram-reaction-negative, facultatively anaerobic, oval-shaped, motile with two flagella and catalase- and oxidase-positive. Growth of strain 011410T was observed at 4-41 °C (optimum, 30 °C), at pH 4.5-10.0 (optimum, pH 8.0) and at salinities of 0-10 % (w/v) NaCl (optimum, 0-2 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 011410T was a member of the genus Paracoccus and was related most closely to Paracoccus aestuarii B7T (96.62 % similarity) and Paracoccus sediminis CMB17T (96.48 % similarity). The major fatty acid was identified as C18 : 1ω7c, with smaller amounts of C18 : 0, C10 : 0 3-OH and summed feature 2 (C14 : 0 3-OH and/or iso-C16 : 1 I). The predominant respiratory quinone was ubiquinone-10 (Q-10), with Q-9 as a minor component. Polar lipid analysis indicated the presence of diphosphatidylglycerol, phosphatidylglycerol, one unknown phosphoglycolipid, five unknown phospholipids, one unknown aminolipid, one unknown glycolipid and two unknown polar lipids. The DNA G+C content of the strain was 63.5 mol%. On the basis of the data from this polyphasic characterization, strain 011410T represents a novel species, for which the name Paracoccus aerius sp. nov. is proposed. The type strain is 011410T (=CFCC 14285T=KCTC 42845T).

Isolation and Complete Genome Sequence of Algibacter alginolytica sp. nov., a Novel Seaweed-Degrading Bacteroidetes Bacterium with Diverse Putative Polysaccharide Utilization Loci

The members of the phylum Bacteroidetes are recognized as some of the most important specialists for the degradation of polysaccharides. However, in contrast to research on Bacteroidetes in the human gut, research on polysaccharide degradation by marine Bacteroidetes is still rare. The genus Algibacter belongs to the Flavobacteriaceae family of the Bacteroidetes, and most species in this genus are isolated from or near the habitat of algae, indicating a preference for the complex polysaccharides of algae. In this work, a novel brown-seaweed-degrading strain designated HZ22 was isolated from the surface of a brown seaweed (Laminaria japonica). On the basis of its physiological, chemotaxonomic, and genotypic characteristics, it is proposed that strain HZ22 represents a novel species in the genus Algibacter with the proposed name Algibacter alginolytica sp. nov. The genome of strain HZ22, the type strain of this species, harbors 3,371 coding sequences (CDSs) and 255 carbohydrate-active enzymes (CAZymes), including 104 glycoside hydrolases (GHs) and 18 polysaccharide lyases (PLs); this appears to be the highest proportion of CAZymes (∼7.5%) among the reported strains in the class Flavobacteria Seventeen polysaccharide utilization loci (PUL) are predicted to be specific for marine polysaccharides, especially algal polysaccharides from red, green, and brown seaweeds. In particular, PUL N is predicted to be specific for alginate. Taking these findings together with the results of assays of crude alginate lyases, we prove that strain HZ22(T) can completely degrade alginate. This work reveals that strain HZ22(T) has good potential for the degradation of algal polysaccharides and that the structure and related mechanism of PUL in strain HZ22(T) are worth further research.

Paracoccus angustae sp. nov., isolated from soil

A Gram-stain-negative, coccus-shaped, aerobic bacterium, strain E6T, was isolated from soil. 16S rRNA gene sequence analysis revealed a cluster containing strain E6T and Paracoccus sediminis CMB17T (the highest 16S rRNA gene similarity of 97.2 %). The other strains investigated showed 16S rRNA gene sequence similarities of less than 97 % to strain E6T. The DNA–DNA relatedness between strain E6T and P. sediminis DSM 26170T was 59.2 %. Strain E6T also shows some differences compared with other Paracoccus strains such as motility and inability to utilize lactate and propionate as sole carbon sources. The major fatty acids of strain E6T were C18 : 1ω7c and C18 : 0 and ubiquinone-10 was the only respiratory quinone. Strain E6T had diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, an unknown aminolipid and an unknown glycolipid as major polar lipids. The genomic DNA G+C content was 68.1 mol%. On the basis of phenotypic and genotypic characteristics, strain E6T is concluded to represent a novel species of the genus Paracoccus, for which the name Paracoccus angustae sp. nov. is proposed. The type strain is E6T ( = KCTC 42473T = CCTCC AB 2015056T).

Paracoccus laeviglucosivorans sp. nov., an l-glucose-utilizing bacterium isolated from soil

Strain 43P^T was isolated as an l-glucose-utilizing bacterium from soil in Japan. Cells of the strain were Gram-stain-negative, aerobic and non-motile cocci. The 16S rRNA gene sequence of the strain showed high similarity to that of Paracoccus limosus (98.5 %). Phylogenetic analyses based on 16S rRNA gene sequences revealed that this strain belongs to the genus Paracoccus. Strain 43P^T contained Q-10 as the sole isoprenoid quinone. The major cellular fatty acids were C_18: 1ω7c or C_18: 1ω6c and C_16: 0, and C_18: 0, C_18: 1ω9c, C_10: 0 3-OH and summed feature 2 were detected as minor components. The DNA G+C content of strain 43P^T was 64.1 mol%. Strain 43P^T contained the major polar lipids phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, an unknown aminolipid and two unknown glycolipids. The DNA-DNA relatedness between strain 43P^T and the six related type strains of the genus Paracoccus, including P. limosus, was below 23 %. Based on the chemotaxonomic and physiological data and the values of DNA-DNA relatedness, especially the ability to assimilate l-glucose, this strain should be classified as a representative of a novel species of the genus Paracoccus, for which the name Paracoccus laeviglucosivorans sp. nov. (type strain 43P^T = JCM 30587^T = DSM 100094^T) is proposed.