Altererythrobacter epoxidivorans gen. nov., sp. nov., an epoxide hydrolase-active, mesophilic marine bacterium isolated from cold-seep sediment, and reclassification of Erythrobacter luteolus Yoon et al. 2005 as Altererythrobacter luteolus comb. nov

Simultaneous high molecular weight PAHs degradation and chromate and arsenite detoxification by Altererythrobacter sp. H2

The cooccurrence of high molecular weight PAHs and heavy metals Cr and As is frequently observed in soil and water and challenges public health and environmental management. Yet the limited microbial resources were reported to simultaneously detoxify PAHs, Cr(VI) and As(III), which restricts the bioremediation of co-contaminated soil by PAHs, Cr and As. Here, we isolated Altererythrobacter sp. H2 and found it could degrade various PAHs, including phenanthrene, fluoranthene, pyrene, benzo[a]anthracene, and benzo[a]pyrene, and tolerate and detoxify high concentrations of Cr(VI) and As(III). Genomic, transcriptomic, and biochemical assays reveal strain H2 degrades PAHs, reduces Cr(VI), and oxidize As(III) via a horizontally transferred RHO gene cluster, a chromate reductase ChrR, and a arsenite resistance gene cluster arsRBC. The horizontally transferred PAHs-degrading gene cluster encodes the Rieske dioxygenase three-component system and other enzymes required for PAHs degradation, which suggested those heavy metal-detoxifying bacteria could be excellent PAHs-degrading and heavy metal-detoxifying agents after accommodating a PAHs degradation gene cluster like strain H2 did. To our knowledge, strain H2 is the only reported Altererythrobacter member that uses a classical Rieske dioxygenase three-component system to initial PAHs degradation and the only one could simultaneously detoxify PAHs, Cr(VI), and As(III). Our study provides insights into the PAHs degradation mechanism of Altererythrobacter members and demonstrates the excellent potential of H2 in the bioremediation of both PAHs and heavy metal pollutants.

Altererythrobacter arenosus sp. nov., Isolated from Marine Sediment

Strain CAU 1644T was isolated from sea sand at Ganghwa Island, Republic of Korea. The bacterium is aerobic, Gram-staining negative, yellow-colored, non-motile, catalase-positive, and rod-shaped. Cells of strain CAU 1644T grew at 20-40 °C and pH 6.0-10.0 with 0%-3.0% (w/v) NaCl. The 16S rRNA gene sequences of Altererythrobacter epoxidivorans CGMCC 1.7731T (identity, 98.5%) and A. xiamenensis CGMCC 1.12494T (98.0%) had the highest similarities to strain CAU 1644T. Strain CAU 1644T exhibits affiliation with the genus Altererythrobacter by phylogenetic trees based on the 16S rRNA gene and core-genome sequences. The predominant quinone was ubiquinone-10 (Q-10) and the major fatty acids were summed feature 8 (C18:1ω7c and/or C18:1ω6c) and summed feature 3 (C16:1ω7c and/or C16:1ω6c). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values of strain CAU 1644T were 77.6% and 20.1% with A. epoxidivorans CGMCC 1.7731T, respectively, and 77.4% and 21.0% with A. xiamenensis CGMCC 1.12494T. The G + C content is 62.5%. Based on phenotypic and genotypic analyses, strain CAU 1644T represents a novel species of the genus Altererythrobacter, for which the name Altererythrobacter arenosus sp. nov., is proposed. The type strain is CAU 1644T (= KCTC 92082T = MCCC 1K07086T).

Aurantiacibacter flavus sp. nov. and Aurantiacibacter gilvus sp. nov., isolated from the mudflat of Suaeda japonica colonies

Two novel strains were isolated from the mudflat of Suaeda japonica colonies in Incheon, Republic of Korea. Designated as DGU5T and DGU6T, these strains were Gram-stain-negative, facultatively anaerobic and rod-shaped and had yellowish colonies. Both strains were determined to belong to the genus Aurantiacibacter through phylogenetic analysis of their 16S rRNA sequences and draft genomes. The cells of strain DGU5T were non-motile and grew at temperatures ranging between 7-45°C (optimum, 25-30°C), pH 6.0-10.0 (optimum, 7.0-8.0) and in the presence of 0-11.0% NaCl (optimum, 2.0%). The cells of strain DGU6T were non-motile and grew in temperatures ranging from 10-45 °C (optimum, 30-35°C), pH 3.0-10.0 (optimum, 7.0-8.0) and in the presence of 0-11.0% NaCl (optimum, 2.0%). Overall genome relatedness index calculations revealed average nucleotide identity values (72.3-88.6%) and digital DNA-DNA hybridization values (18.8-35.9%) aligning with those of the genus Aurantiacibacter. The major fatty acids in both strains were C17:1 ω6c and summed feature 8 (C18:1 ω6c/C18:1 ω7c), while the predominant polar lipids were sphingoglycolipid, phosphatidylglycerol, and diphosphatidylglycerol. Phylogenetic, average nucleotide identity, digital DNA-DNA hybridization, physiological, and biochemical data collectively demonstrated the distinctiveness of the novel strains from other members within the family Erythrobacteraceae. We propose the names A. flavus sp. nov. (type strain DGU5T = KACC 23720T = TBRC 19015T) and A. gilvus sp. nov. (type strain DGU6T = KACC 23721T = TBRC 19016T) for the two strains.

Altererythrobacter litoralis sp. nov., a New Carotenoid-Producing Member of the Family Erythrobacteraceae, Isolated from a Tidal Flat Sediment

A new isolate designated as 1XM1-14T was isolated from a tidal flat sediment of Xiamen Island. The yellow-pigmented colonies and rod-shaped cells were observed. Strain 1XM1-14T could hydrolyze Tweens 20, 40, 60, aesculin, and skim milk, and was chemoheterotrophic and mesophilic, required NaCl for the growth. The 16S rRNA gene-based phylogenetic analysis indicated that strain 1XM1-14T was the most closely related to Altererythrobacter epoxidivorans CGMCC 1.7731T (97.0%), followed by other type strain of the genus Altererythrobacter with identities below 97.0%. The DNA-DNA hybridization and average nucleotide identity values between strain 1XM1-14T and its relatives of the genus Altererythrobacter were below the respective thresholds for prokaryotic species demarcation. The phylogenomic inference further revealed that strain 1XM1-14T formed a separate branch distinct from the type strains of the recognized species within the genus Altererythrobacter. The major cellular fatty acids of strain 1XM1-14T were identified as summed feature 8 (C18:1 ω6c and/or C18:1 ω7c), C17:1 ω6c, and C16:0; the profile of polar lipids comprised diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, sphingoglycolipid, an unidentified glycolipid, and two unidentified lipids; the respiratory quinone was determined to ubiquinone-10. The genomic size and DNA G+C content of strain 1XM1-14T were 2.5 Mbp and 62.71%. The key carotenoid biosynthetic genes were determined in the genome of strain 1XM1-14T and the generated carotenoids were detected. The combined genotypic and phenotypic characteristics supported the classification of strain 1XM1-14T (= GDMCC 1.2383T = KCTC 82612T) as a novel species in the genus Altererythrobacter, for which the name Altererythrobacter litoralis sp. nov. is proposed.

Alteriqipengyuania flavescens sp. nov., isolated from Pearl River Estuary sediment

Two Gram-stain-negative, aerobic, rod-shaped, non-motile and golden yellow pigmented bacteria, designated as SCSIO 75105T and SCSIO 75732, were isolated from sediment in the Pearl River Estuary, Guangdong Province, PR China. Cells were positive for catalase and oxidase. Growth occurred at 10-37 °C (optimum, 28 °C), pH 6.0-10.0 (optimum, pH 7.0) and 0-5.0 % (w/v) NaCl (optimum, 2.0-3.0 %). The 16S rRNA gene analysis indicated that these two isolates shared a similarity of 100 % each other. The 16S rRNA gene sequence analysis indicated that these two isolates showed highest similarity to Altererythrobacter ishigakiensis CGMCC 1.14979T (97.3 %). However, a phylogenetic tree based on 288 orthologous clusters indicated that these two isolates were closely related to Alteriqipengyuania halimionae CPA5T. The average nucleotide identity, average amino acid identity, digital DNA-DNA hybridization and evolutionary distance values between the two isolates and Alteriqipengyuania halimionae CPA5T were 73.7-74.0 %, 65.2 %, 19.5 % and 0.24, respectively. The genomic DNA G+C content of both isolates was 65.2 mol%. The major cellular fatty acids were C18 : 1  ω7c, C17 : 1  ω6c and summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c), and Q-10 was the respiratory quinone. The polar lipid profile contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, sphingoglycolipid and one unidentified glycolipid. On the basis of the results of phenotypic, physiological, chemotaxonomic and genotypic characterization, strains SCSIO 75105T and SCSIO 75732 are considered to represent a novel species in the genus Alteriqipengyuania, for which the name Alteriqipengyuania flavescens sp. nov. is proposed. The type strain is SCSIO 75105T (=KCTC 92502T=MCCC 1K07993T).

Nitrogen transformation in slightly polluted surface water by a novel biofilm reactor: Long-term performance and microbial population characteristics

This study proposes a modular floating biofilm reactor (MFBR) for in situ nitrogen removal from slightly polluted water in rivers using enriched indigenous microorganisms. Its main structure is a 60 cm × 60 cm × 90 cm rectangular reactor filled with hackettens. After a 96-day startup, the removal efficiencies of ammonia-N and total N (TN) reached 80% and 25%, respectively, with a hydraulic retention time (HRT) of 10 h, whereas those in a control reactor (without biofilm) were only 4.9% and 0.2%, respectively. The influences of HRT and dissolved oxygen (DO) were also investigated. As a key factor, HRT significantly affected the removal efficiencies of ammonia-N and TN. When HRT was close to the actual value for a river studied (2.4 min), the removal efficiencies of ammonia-N and TN were only 8.7% and 3.1%, respectively. Aeration increased the concentration of DO in water, which enhanced nitrification but inhibited denitrification. When HRT was 2.4 min, aeration intensity was 20 L/min; the ammonia-N and TN removal rates were 9.5 g/(m²·d) and 11.3 g/(m²·d), respectively. The results of microbial community analysis indicated that the microorganisms forming the biofilm were indigenous bacteria. The findings demonstrated a concept-proof of MFBR, which may be evaluated in scaling up investigation for developing a new methodology for nitrogen removal from slightly polluted surface water in plain river networks.

Structure and Function Insight of the α-Glucosidase QsGH13 From Qipengyuania seohaensis sp. SW-135

The α-glucosidases play indispensable roles in the metabolic mechanism of organism, prevention, and treatment of the disease, and sugar hydrolysis, and are widely used in chemical synthesis, clinical diagnosis, and other fields. However, improving their catalytic efficiency and production to meet commercial demand remains a huge challenge. Here we detected a novel GH13 family α-glucosidase, QsGH13, from the deep-sea bacterium Qipengyuania seohaensis sp. SW-135. QsGH13 is highly substrate specific and only hydrolyzes sugars containing alpha-1,4 glucoside bonds. For example, its enzymatic activity for p-nitrophenyl-α-D-glucopyranoside was 25.41 U/mg, and the K_m value was 0.2952 ± 0.0322 mM. The biochemical results showed that the optimum temperature of QsGH13 is 45°C, the optimum pH is 10.0, and it has excellent biological characteristics such as alkali resistance and salt resistance. The crystal structure of QsGH13 was resolved with a resolution of 2.2 Å, where QsGH13 is composed of a typical TIM barrel catalytic domain A, a loop-rich domain B, and a conserved domain C. QsGH13 crystal belonged to the monoclinic space group P2₁2₁2₁, with unit-cell parameters a = 58.816 Å, b = 129.920 Å, c = 161.307 Å, α = γ = β = 90°, which contains two monomers per asymmetric unit. The β → α loop 4 of QsGH13 was located above catalytic pocket. Typical catalytic triad residues Glu202, Asp266, and Glu329 were found in QsGH13. The biochemical properties and structural analysis of QsGH13 have greatly improved our understanding of the catalytic mechanism of GH13 family. This study provides new ideas to broaden the application of α-glucosidase in alcohol fermentation, glycolysis, and other industries.

Altererythrobacter lutimaris sp. nov., a marine bacterium isolated from a tidal flat and reclassification of Altererythrobacter deserti, Altererythrobacter estronivorus and Altererythrobacter muriae as Tsuneonella deserti comb. nov., Croceicoccus estronivorus comb. nov. and Alteripontixanthobacter muriae comb. nov

A yellow-coloured bacterium, designated strain JGD-16^T, was isolated from a tidal flat in Janggu-do, Garorim Bay, Taean-gun, Chungcheongbuk-do, Republic of Korea. Cells were Gram-stain-negative, aerobic, non-flagellated and short ovoid to coccoid-shaped. Growth was observed at 10-37 °C (optimum, 30 °C), pH 6.0-9.0 (pH 8.0) and with 1-5% (w/v) NaCl (2%). Results of 16S rRNA gene sequence analysis indicated that strain JGD-16^T was closely related to Altererythrobacter xiamenensis LY02^T (97.1 %), Altererythrobacter aurantiacus O30^T (96.3 %), Altererythrobacter ishigakiensis JPCCMB0017^T (95.8 %), Altererythrobacter epoxidivorans JCS350^T (95.7 %) and Altererythrobacter insulae BPTF-M16^T (95.3%). Phylogenomic analysis using the maximum-likelihood algorithm showed that strain JGD-16^T formed a clade with the genus Altererythrobacter. The genomic DNA G+C content was 57.8 mol%. The predominant respiratory quinone was ubiquinone-10. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, a sphingoglycolipid, an unidentified glycolipid and an unidentified lipid. The major fatty acids were C_18:1 ω7c (31.5 %) and C_18:3 ω6c (19.6 %). On the basis of its phylogenomic, physiological and chemotaxonomical characteristics, strain JGD-16^T represents a novel species within the genus Altererythrobacter, for which the name Altererythrobacter lutimaris JGD-16^Tsp. nov. is proposed. The type strain is JGD-16^T (=KCTC 72632^T=KACC 21405^T=JCM 33750^T). We also propose the reclassification of Altererythrobacter deserti as Tsuneonella deserti comb. nov., Altererythrobacter estronivorus as Croceicoccus estronivorus comb. nov. and Altererythrobacter muriae as Alteripontixanthobacter muriae comb. nov.

Bacterial and Archaeal Structural Diversity in Several Biodeterioration Patterns on the Limestone Walls of the Old Cathedral of Coimbra

The “University of Coimbra-Alta and Sofia” area was awarded the UNESCO World Heritage Site distinction in 2013. The Old Cathedral of Coimbra, a 12th-century limestone monument located in this area, has been significantly impacted during the last 800 years by physical, chemical, and biological processes. This led to the significant deterioration of some of its structures and carvings, with loss of aesthetical, cultural, and historical values. For this work, deteriorated spots of the walls of three semi-open chapels from the cloister of the Cathedral were sampled to ascertain their bacterial and archaeal structural diversity. Based on Next-Generation Sequencing (NGS) result analysis, we report the presence of microbial populations that are well adapted to an ecosystem with harsh conditions and that can establish a diverse biofilm in most cases. While it was possible to determine dominant phylogenetic groups in Archaea and Bacteria domains, there was no clear connection between specific core microbiomes and the different deterioration patterns analyzed. The distribution of these archaeal and bacterial communities within the analyzed biodeterioration spots suggests they are more influenced by abiotic factors (i.e., water availability, salinity, etc.), although they influence (and are influenced by) the algal and fungal population composition in this ecosystem. This work provides valuable information that can assist in establishing future guidelines for the preservation and conservation of this kind of historic stone monuments.

Altererythrobacter muriae sp. nov., isolated from hypersaline Añana Salt Valley spring water, a continental thalassohaline-type solar saltern

A novel salt-tolerant alpha-proteobacterium, designated SALINAS58^T, was isolated from Santa Engracia hypersaline spring water in the Añana Salt Valley, Álava, Spain. The isolate was Gram-negative, aerobic, non-motile, catalase-positive, oxidase-negative, rod-shaped and formed orange colonies on marine agar. Optimal growth was observed at pH 6.0-6.5, at 30 °C and in the presence of 1% (w/v) NaCl. The main cellular fatty acids (>20%) were summed feature 8 (C_{18 : 1} ω7c and/or C_{18 : 1} ω6c) and summed feature 3 (C_{16 : 1} ω7c and/or C_{16 : 1} ω6c). The major respiratory quinone was ubiquinone Q-10 and the major polar lipids detected were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidilglycerol, four unidentified glycolipids and one unidentified phospholipid. Strain SALINAS58^T had the highest 16S rRNA gene sequence similarity to Altererythrobacter marensis MSW-14^T (96.6%), Altererythrobacter aquaemixtae JSSK-8^T (96.5%) and Pontixanthobacter luteolus SW-109^T (96.5%) followed by Altererythrobacter atlanticus 26DY36^T (96.4%). Results of the phylogenetic analysis, based on 16S rRNA gene sequences, and phylogenetic approaches based on whole genome nucleotide differences, showed that strain SALINAS58^T could be distinguished from recognized species of the genus Altererythrobacter. The genomic DNA G+C content was 61.4 mol%. Digital DNA-DNA hybridization, average nucleotide identity and average aminoacid identity values between the genome of strain SALINAS58^T and A. marensis MSW-14^T were 18.4, 73.1 and 68.1%, respectively. Based on data from this polyphasic characterization, strain SALINAS58^T (=CECT 30029^T=LMG 31726^T) is considered to be classified as representing a novel species in the genus Altererythrobacter, for which the name Altererythrobacter muriae sp. nov. is proposed.

Altererythrobacter flava sp. nov., a new member of the family Erythrobacteraceae, isolated from a surface seawater sample

A Gram-stain-negative, light yellow pigmented, non-motile and aerobic bacterial strain, designated HHU E2-1 ^T, was isolated from a surface seawater sample. The 16S rRNA gene sequence analysis indicated that HHU E2-1 ^T shared the highest sequence similarity to the type strain Qipengyuania gaetbuli DSM 16225 ^T (96.90%), which belongs to the family Erythrobacteraceae. Combined phylogeny of 288 single-copy orthologous gene clusters, analysis of average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH), average amino acid identity (AAI) and evolutionary distances suggested that HHU E2-1 ^T can be considered as a member of the genus Altererythrobacter based on the recently proposed standard for defining genera of Erythrobacteraceae. Strain HHU E2-1 ^T grew at 15-35 °C and pH 5.0-8.0, with optimum growth at 28 °C and pH 7.0. Tolerance to NaCl was up to 4% (w/v) with optimum growth in 2-3% NaCl. The major fatty acids (> 10%) were C_18:1ω7c11-methyl, summed feature 3 (C_16:1ω7c and/or C_16:1ω6c), and summed feature 8 (C_18:1ω7c and/or C_18:1ω6c). The predominant isoprenoid quinone was ubiquinone-10. The genomic G + C content was 57.40%. On the basis of the phenotypic, phylogenetic and chemotaxonomic characterizations, HHU E2-1 ^T represents a novel species of the genus Altererythrobacter, for which the name Altererythrobacter flava sp. nov. is proposed. The type strain is HHU E2-1 ^T (= CGMCC 1.17394 ^T = KCTC 72835 ^T = MCCC 1K04226^T).

Tsuneonella suprasediminis sp. nov., isolated from the Pacific Ocean

A Gram-stain-negative, rod-shaped and aerobic bacterial strain, named Ery12^T, was isolated from the overlying water of the Lau Basin in the Southwest Pacific Ocean. Strain Ery12^T showed high 16S rRNA gene sequences similarity to Tsuneonella flava MS1-4^T (99.9 %), T. mangrovi MCCC 1K03311^T (98.1 %), Altererythrobacter ishigakiensis NBRC 107699^T (97.3 %) and exhibited ≤97.0 % sequence similarity with other type strains of species with validly published names. Growth was observed in media with 0-10.0 % NaCl (optimum 0-1.0 %, w/v), pH 5.0-9.5 (optimum 6.0-7.0) and 10-42 °C (optimum 30-37 °C). The predominant respiratory quinone was ubiquinone 10 (Q-10). The major cellular fatty acid was summed feature 8 (C_18 : 1  ω7c and/or C_18 : 1  ω6c). The major polar lipids were sphingoglycolipid, phosphatidyglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, three unidentified glycolipids, one unidentified aminoglycolipid and one unidentified lipid. The DNA G+C content was 60.8 %. The ANI and in silico DDH values between strain Ery12^T and the type strains of its closely related species were 71.0- 91.8 % and 19.5- 44.6 %, respectively. According to the phenotypic, chemotaxonomic, phylogenetic and genomic data, strain Ery12^T represents a novel species of the genus Tsuneonella, for which the name Tsuneonella suprasediminis is proposed. The type strain is Ery12^T (=CGMCC 1.16500 ^T=MCCC 1A04421^T=KCTC 62388^T). We further propose to reclassify Altererythrobacter rhizovicinus and Altererythrobacter spongiae as Pelagerythrobacter rhizovicinus comb. nov. and Altericroceibacterium spongiae comb. nov., respectively.

Altererythrobacter segetis sp. nov., Isolated from Farmland Soil

A Gram-stain-negative bacterium, designated YJ20^T, was isolated from rhizosphere soil of a spinach farmland at Shinan in Korea. Strain YJ20^T was found to be aerobic, non-motile rods which can grow at 10-33 °C (optimum, 28 °C), at pH 6.5-8.5 (optimum, pH 6.5-7.5) and in the absence of NaCl. The 16S rRNA gene sequence analysis showed that strain YJ20^T belongs to the genus Altererythrobacter with moderate sequence similarities to Altererythrobacter dongtanensis KCTC 22672^T (96.8%), Altererythrobacter soli MN-1^T (96.6%) and Altererythrobacter xinjiangensis S3-63^T (96.5%). The phylogenomic analysis based on the whole-genome sequence demonstrated that strain YJ20^T formed a distinct phyletic line with Altererythrobacter soli MN-1^T and Altererythrobacter salegens XY-R17^T showing average nucleotide identity (ANI) values of 79.4 and 77.5%, respectively. The predominant ubiquinone was identified as Q-10, and the major fatty acids were C_17:1 ω6c, C_18:1 ω7c and C_15:0 2-OH. The major polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidycholin, sphingoglycolipid, an unidentified glycolipid, an unidentified phospholipid and an unidentified lipid. The G+C content of the genome was determined to be 66.3 mol%. On the basis of phenotypic, chemotaxonomic properties and phylogenetic and phylogenomic analyses in this study, strain YJ20^T is considered to represent a novel species in the genus Altererythrobacter, for which the name Altererythrobacter segetis sp. nov. is proposed. The type strain is YJ20^T (= KACC 19554^T = NBRC 113199^T).

Pseudopontixanthobacter vadosimaris gen. nov., sp. nov., isolated from shallow sea near Kueishan Island

A Gram-stain-negative and aerobic bacterial strain, designated as JL3514^T, was isolated from surface water of the hydrothermal system around Kueishan Island. The isolate formed red colonies and cells were non-flagellated, rod-shaped and contained methanol-soluble pigments. Growth was observed at 10-50 °C (optimum, 30 °C), at pH 5.0-9.0 (optimum, pH 7.0) and in the presence of 0-9 % (w/v) NaCl (optimum, 2 %). Strain JL3514^T was positive for catalase and weakly positive for oxidase. Results of 16S rRNA gene sequence analyses showed highest similarities to species in the family Erythrobacteraceae, namely Croceibacterium atlanticum (96.1 %), Pelagerythrobacter marensis (96.0 %), Tsuneonella rigui (96.0 %) and Altericroceibacterium xinjiangense (96.0 %). Phylogenetic analysis based on core gene sequences revealed that the isolate formed a distinct branch with the related species and it had a lower average amino acid identity value than the suggested threshold for genera boundaries. The major fatty acids (>5 %) were summed feature 8 (C_18 : 1  ω7c and/or C_18 : 1  ω6c), summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c), C_16 : 0, C_17 : 1  ω6c, C_14 : 0 2-OH and C_12 : 0. The dominant polar lipids comprised diphosphatidylglycerol, sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, glycolipid, two unidentified lipids and one unidentified phospholipid. The main respiratory quinones were ubiquinone-10 (95.7 %) and ubiquinone-9 (4.3 %). The DNA G+C content from the genome was 63.0 mol%. Based on the presented data, we consider strain JL3514^T to represent a novel genus of the family Erythrobacteraceae, with the name Pseudopontixanthobacter vadosimaris gen. nov., sp. nov. The type strain is JL3514^T (=KCTC 62623^T=MCCC 1K03561^T).

Genomic-based taxonomic classification of the family Erythrobacteraceae

The family Erythrobacteraceae, belonging to the order Sphingomonadales, class Alphaproteobacteria, is globally distributed in various environments. Currently, this family consist of seven genera: Altererythrobacter, Croceibacterium, Croceicoccus, Erythrobacter, Erythromicrobium, Porphyrobacter and Qipengyuania. As more species are identified, the taxonomic status of the family Erythrobacteraceae should be revised at the genomic level because of its polyphyletic nature evident from 16S rRNA gene sequence analysis. Phylogenomic reconstruction based on 288 single-copy orthologous clusters led to the identification of three separate clades. Pairwise comparisons of average nucleotide identity, average amino acid identity (AAI), percentage of conserved protein and evolutionary distance indicated that AAI and evolutionary distance had the highest correlation. Thresholds for genera boundaries were proposed as 70 % and 0.4 for AAI and evolutionary distance, respectively. Based on the phylo-genomic and genomic similarity analysis, the three clades were classified into 16 genera, including 11 novel ones, for which the names Alteraurantiacibacter, Altericroceibacterium, Alteriqipengyuania, Alteripontixanthobacter, Aurantiacibacter, Paraurantiacibacter, Parerythrobacter, Parapontixanthobacter, Pelagerythrobacter, Tsuneonella and Pontixanthobacter are proposed. We reclassified all species of Erythromicrobium and Porphyrobacter as species of Erythrobacter. This study is the first genomic-based study of the family Erythrobacteraceae, and will contribute to further insights into the evolution of this family.

Description of Erythrobacter mangrovi sp. nov., an aerobic bacterium from rhizosphere soil of mangrove plant (Kandelia candel)

A novel Gram-stain negative, aerobic, non-motile, rod-shaped bacterium, designated as strain EB310^T, was isolated from rhizosphere soil of mangrove plant Kandelia candel in Fugong village, Zhangzhou, China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain EB310^T belonged to the genus Erythrobacter, clustering with Erythrobacter pelagi JCM 17468^T, Erythrobacter lutimaris KCTC 42109^T and Erythrobacter marisflavi KCTC 62896^T, and showed the highest 16S rRNA gene sequence similarity of 97.5% to Erythrobacter pelagi JCM 17468^T. The genomic average nucleotide identity and in silico DNA-DNA hybridization values between strain EB310^T and the reference strains were 71.0-75.5% and 19.8-20.0%, respectively. Growth ranges of the isolate occurred at 10-45 °C (optimum 28-30 °C), pH 5.5-9.5 (optimum pH 7.5) and 0-9.0% NaCl concentrations (optimum 2.0%, w/v). The strain did not produce bacteriochlorophyll a and flexirubin, but produced carotenoids. The strain contained Q-10 as the predominant ubiquinone and summed feature 3 (C_16:1 ω7c/C_16:1 ω6c) and summed feature 8 (C_18:1 ω6c/C_18:1 ω7c) as the major fatty acids. The major polar lipids were sphingoglycolipid, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylcholine. Differential phenotypic characteristics, together with chemotaxonomic, phylogenetic and genomic distinctiveness, indicated that strain EB310^T is distinguishable from other members of the genus Erythrobacter. On the basis of the data exhibited, strain EB310^T is considered to represent a novel species of the genus Erythrobacter, for which the name Erythrobacter mangrovi sp. nov., is proposed. The type strain is EB310^T (= KCTC 72109^T = MCCC 1K03690^T). The genomic DNA G + C content is 62.9 mol%.

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.

Shear Stress as a Major Driver of Marine Biofilm Communities in the NW Mediterranean Sea

While marine biofilms depend on environmental conditions and substrate, little is known about the influence of hydrodynamic forces. We tested different immersion modes (dynamic, cyclic and static) in Toulon Bay (north-western Mediterranean Sea; NWMS). The static mode was also compared between Toulon and Banyuls Bays. In addition, different artificial surfaces designed to hamper cell attachment (self-polishing coating: SPC; and fouling-release coating: FRC) were compared to inert plastic. Prokaryotic community composition was affected by immersion mode, surface characteristics and site. Rhodobacteriaceae and Flavobacteriaceae dominated the biofilm community structure, with distinct genera according to surface type or immersion mode. Cell density increased with time, greatly limited by hydrodynamic forces, and supposed to delay biofilm maturation. After 1 year, a significant impact of shear stress on the taxonomic structure of the prokaryotic community developed on each surface type was observed. When surfaces contained no biocides, roughness and wettability shaped prokaryotic community structure, which was not enhanced by shear stress. Conversely, the biocidal effect of SPC surfaces, already major in static immersion mode, was amplified by the 15 knots speed. The biofilm community on SPC was 60% dissimilar to the biofilm on the other surfaces and was distinctly colonized by Sphingomonadaceae ((Alter)Erythrobacter). At Banyuls, prokaryotic community structures were more similar between the four surfaces tested than at Toulon, due possibly to a masking effect of environmental constraints, especially hydrodynamic, which was greater than in Toulon. Finally, predicted functions such as cell adhesion confirmed some of the hypotheses drawn regarding biofilm formation over the artificial surfaces tested here.

Croceibacterium gen. nov., with description of Croceibacterium ferulae sp. nov., an endophytic bacterium isolated from Ferula sinkiangensis K. M. Shen and reclassification of Porphyrobacter mercurialis as Croceibacterium mercuriale comb. nov

A novel endophytic bacterium, designated strain SX2RGS8^T, was isolated from the surface-sterilized roots of an endangered medicinal plant (Ferula sinkiangensis K. M. Shen) collected from Xinjiang, north-western PR China. The taxonomic position of the candidate was investigated using a polyphasic approach. Strain SX2RGS8^T was found to be aerobic, Gram-stain-negative, oxidase-negative, catalase-positive and axiolitic-shaped. Strain SX2RGS8^T grew at 4-45 °C (optimum, 28 °C), pH 4.0-10.0 (pH 7.0) and in the presence of 0-5 % (w/v) NaCl. The polar lipids detected for strain SX2RGS8^T were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, unidentified phosphoglycolipids, an unidentified phospholipid and unidentified lipids. The major respiratory quinone of strain SX2RGS8^T was ubiquinone 10 and the major fatty acid was summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The DNA G+C content was determined to be 66.5 mol%. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the isolate belonged to the family Erythrobacteraceae and showed 99.2 % (Porphyrobacter mercurialis), 95.5 % (Porphyrobacter donghaensisi) and 95.4 % (Porphyrobacter colymbi) similarities to its closest relatives. The isolate contained carotenoids, but no bacteriochlorophyll a. On the basis of phenotypic, genotypic and phylogenetic data, strain SX2RGS8^T represents a novel species of a novel genus in the family Erythrobacteraceae, for which the name Croceibacterium ferulae gen. nov., sp. nov. is proposed. The type strain is SX2RGS8^T (=CGMCC 1.16402^T=KCTC 62090^T). In addition, Porphyrobacter mercurialis Coil et al. 2016 is proposed to be transferred to this new genus as Croceibacterium mercuriale comb. nov.

Altererythrobacter aquimixticola sp. nov., isolated from sediment sampled at the junction between the ocean and a freshwater spring

A Gram-stain-negative, aerobic, non-motile and coccoid-, ovoid- or rod-shaped bacterial strain, designated SSKS-13^T, was isolated from sediment sampled at the junction between the ocean and a freshwater spring at Jeju island, Republic of Korea. Strain SSKS-13^T grew optimally at 37 °C and in the presence of 2.0 % (w/v) NaCl. A neighbour-joining phylogenetic tree of 16S rRNA gene sequences showed that strain SSKS-13^T fell within the clade comprising the type strains of Altererythrobacter species, clustering with the type strains of Altererythrobacter lauratis, Altererythrobacter palmitatis and Altererythrobacter buctensis having 16S rRNA gene sequence similarities of 97.2-97.6 %. Strain SSKS-13^T exhibited 16S rRNA gene sequence similarities of less than 97.0 % to the type strains of the other recognized species. Strain SSKS-13^T contained Q-10 as the predominant ubiquinone and C18 : 1 ω7c as the major fatty acid. The major polar lipids detected in strain SSKS-13^T were phosphatidylethanolamine, phosphatidylglycerol and sphingoglycolipid. The DNA G+C content of strain SSKS-13^T was 64.6 mol%. The mean DNA-DNA relatedness values of strain SSKS-13^T with the type strains of A. lauratis, A. palmitatis and A. buctensis were 11.7-25.3 %. Differential phenotypic properties, together with the phylogenetic and genetic data, proved that strain SSKS-13^T is distinct from recognized Altererythrobacter species. On the basis of the data presented here, strain SSKS-13^T is considered to represent a novel species of the genus Altererythrobacter, for which the name Altererythrobacter aquimixticola sp. nov. is proposed. The type strain is SSKS-13^T (=KACC 19863^T=KCTC 62900^T=NBRC 113545^T).

Altererythrobacter lutipelagi sp. nov., isolated from a tidal mudflat, and emended description of the genus Altererythrobacter

A marine proteobacterium, designated strain GH1-16^T, was isolated from a sample of tidal mudflat collected at the seashore of Gangwha Island, Republic of Korea and the taxonomic status was examined by a polyphasic approach. The isolate was Gram-reaction-negative, strictly aerobic, catalase- and oxidase-positive, non-motile, short-rod-shaped and produced yellow-coloured colonies. An absolute requirement for Na⁺ was observed. The major respiratory quinone was ubiquinone-10. The major polar lipids consisted of phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and sphingoglycolipid. The dominant cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C17 : 1ω6c. The DNA G+C content was 60.6 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain GH1-16^T was closely related to members of the genus Altererythrobacter. The closest relative was Altererythrobacter marensis MSW-14^T (97.3 % sequence similarity) followed by Altererythrobacter aquaemixtae JSSK-8^T (96.8 %) and Altererythrobacter epoxidivorans JCS350^T (96.7 %). The DNA relatedness of strain GH1-16^T against its closest relative was 21.8-25.0 %. On the basis of data obtained by a polyphasic taxonomic approach, strain GH1-16^T (=KCTC 52845^T=NBRC 113275^T) is considered to represent a novel species of the genus Altererythrobacter, for which the name Altererythrobacter lutipelagi sp. nov. is proposed.

Altererythrobacter aerophilus sp. nov., isolated from deep-sea water of the north-west Pacific

A Gram-stain-negative, rod-shaped bacterium, designated Ery1^T, was isolated from deep-sea seawater collected from the Mariana Trench and subjected to a polyphasic investigation for taxonomy. Strain Ery1^T was able to grow in medium containing 0-10 % NaCl (w/v; optimum, 0-1.0 %), pH 5.0-9.5 (optimum, pH 6.0-7.0) and at temperatures between 10-45 °C (optimum, 30-40 °C). The comparison of 16S rRNA gene sequences revealed that strain Ery1^T showed highest similarity to Altererythrobacterxinjiangensis S3-63^T (97.7 %) and Altererythrobacterrigui WW3^T (97.6 %), and exhibited less than 97.5 % sequence similarity to other type strains of the species with validly published names. Phylogenetic analyses indicated that strain Ery1^T fell within the cluster comprising the Altererythrobacter species and formed a coherent clade with Altererythrobacterxinjiangensis and Altererythrobactersoli. The OrthoANIu and in silico DNA-DNA hybridization values between strain Ery1^T and the reference strains were 73.8-75.9 % and 19.2-20.1 %, respectively. Strain Ery1^T contained Q-10 as the major respiratory quinone and Q-11 in a minor amount. The major fatty acids (>10 %) were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0, C18 : 1ω7c 11-methyl and C14 : 0 2-OH. The major polar lipids were sphingoglycolipid, diphosphatidylglycerol, phosphatidyglycerol, phatidylethanolamine, phosphatidylcholine and three unidentified glycolipids. Differential phenotypic properties, chemotaxonomic differences, phylogenetic distinctiveness, together with the genomic data demonstrated that strain Ery1^T represents a novel species of the genus Altererythrobacter, for which named as Altererythrobacter aerophilus sp. nov. with the type strain Ery1^T (=KCTC 62387^T=CGMCC 1.16499^T=MCCC 1A10037^T).

Altererythrobacter amylolyticus sp. nov., isolated from lake sediment

An aerobic, motile, Gram-stain-negative bacterium, designated strain NS1T, was isolated from interfacial sediment from Taihu Lake, China. The strain formed yellow colonies on R2A medium. Cells were ovoid to rod-shaped and non-spore-forming. Growth occurred at 15–40 °C (optimum, 28 °C), at pH 5.0–10.5 (optimum, 6.5–7.5) and in the presence of 0–1 % (w/v) NaCl (optimum, 0 %). Phylogenetic trees based on 16S rRNA gene sequences showed that strain NS1T represented a member of the genus Altererythrobacter and had the highest sequence similarity to Altererythrobacter troitsensis CCTCC AB 2015180T (97.1 %). The average nucleotide identity value between strain NS1T and the closest related strain based on their genomes was 78.6 %. The predominant ubiquinone was Q-10. The major fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The polar lipids comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, an unidentified phospholipid, an unidentified glycolipid and six unidentified lipids. The genomic DNA G+C content was 66.6 mol%. On the basis of phenotypic and genotypic characteristics, strain NS1T represents a novel species of the genus Altererythrobacter , for which the name Altererythrobacter amylolyticus sp. nov. is proposed. The type strain is NS1T (=CGMCC 1.13679T=NBRC 113553T).

Altererythrobacter maritimus sp. nov., isolated from seawater

A rod-shaped, Gram-staining-negative and orange-pigmented bacterium, designated strain HME9302^T, was isolated from seawater of the Yellow Sea in the Republic of Korea. The phylogenetic tree based on 16S rRNA gene sequences showed that strain HME9302^T formed a lineage within the genus Altererythrobacter, and was most closely related to Altererythrobacter aurantiacus O30^T with 96.7 % sequence similarity. The major fatty acids were summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1ω6c), summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The major respiratory quinone was ubiquinone-10. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, sphingoglycolipid and four unidentified lipids. The DNA G+C content was 60.8 mol%. On the basis of the evidence presented in this study, strain HME9302^T represents a novel species of the genus Altererythrobacter, for which the name Altererythrobacter maritimus sp. nov. is proposed with the type strain HME9302^T (=KCTC 32463^T=KACC 17617^T=CECT 8417^T).

Altererythrobacter insulae sp. nov., a lipolytic bacterium isolated from a tidal flat

A lipolytic, Gram-stain-negative, aerobic, non-motile and coccoid, ovoid or rod-shaped bacterial strain, designated BPTF-M16^T, was isolated from tidal flat sediment on the Yellow Sea in the Republic of Korea. Strain BPTF-M16^T grew optimally at 30 °C and in the presence of 2.0-3.0 % (w/v) NaCl. A phylogenetic tree of 16S rRNA gene sequences showed that strain BPTF-M16^T fell within the clade comprising the type strains of Altererythrobacter species. Strain BPTF-M16^T exhibited 16S rRNA gene sequence similarity values of 98.0 and 97.1 % to the type strains of Altererythrobacterishigakiensis and Altererythrobactermarinus, respectively, and of less than 97.0 % to the type strains of the other recognized species. Strain BPTF-M16^T contained Q-10 as the predominant ubiquinone and C18 : 1ω7c as the major fatty acid. The major polar lipids detected in strain BPTF-M16^T were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, sphingoglycolipid and one unidentified glycolipid. Mean DNA-DNA relatedness values of strain BPTF-M16^T with the type strains of A. ishigakiensis and A. marinus were 22 and 13 %, respectively. The average nucleotide identity value between strain BPTF-M16^T and the type strain of A. ishigakiensis was 76.80 %. Differential phenotypic properties, together with the phylogenetic and genetic data, revealed that strain BPTF-M16^T is separated from recognized Altererythrobacter species. On the basis of the data presented here, strain BPTF-M16^T is considered to represent a novel species of the genus Altererythrobacter, for which the name Altererythrobacter insulae sp. nov. is proposed. The type strain is BPTF-M16^T (=KCTC 62421^T=KACC 19609^T=NBRC 113190^T).

Erythrobacter nanhaiensis sp. nov., A Novel Member of the Genus Erythrobacter Isolated from the South China Sea

A Gram-negative, motile, rod-shaped, aerobic bacterial strain with tufty polar flagella, JLT1363^T, was isolated from the South China Sea. The bacteria formed yellow colonies on rich organic medium. The major cellular fatty acids present in JLT1363^T were C_18:1 ω7c and/or C_18:1 ω6c (36.06%), C_17:1 ω6c (17.04%), C_14:0 2-OH (9.85%), and C_16:0 (8.09%). The genome size was ~3.12 Mbps with a G+C content of 64.9%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain JLT1363^T fell within the genus Erythrobacter. The 16S rRNA gene sequence similarity between strain JLT1363^T and the type strains of Erythrobacter species ranged from 95.0% (with Erythromicrobium ramosum) to 98.7% (with Erythrobacter lutimaris). The Average Nucleotide Identity (ANI) value between genome sequences of strain JLT1363^T and Erythrobacter lutimaris KCTC 42109^T was 82.2%. Strain JLT1363^T lacked bacteriochlorophyll a, and the major polar lipids were sphingoglycolipids, diphosphatidylglycerol, phosphatidylcholine, and phosphatidylglycerol. Phylogenetic and phenotypic properties indicated that strain JLT1363^T represents a novel species of the genus Erythrobacter, for which the name Erythrobacter nanhaiensis sp. nov. is proposed. The type strain is JLT1363^T (=CGMCC 1.7293^T = LMG 24872^T).

Complete Genome Sequence of Altererythrobacter sp. Strain B11, an Aromatic Monomer-Degrading Bacterium, Isolated from Deep-Sea Sediment under the Seabed off Kashima, Japan

Altererythrobacter sp. strain B11 is an aromatic monomer-degrading bacterium newly isolated from sediment under the seabed off Kashima, Japan, at a depth of 2,100 m. Here, we report the complete nucleotide sequence of the genome of strain B11.

Characterization of a novel alkaline esterase from Altererythrobacter epoxidivorans CGMCC 1.7731T

A novel esterase gene (e25) was identified from Altererythrobacter epoxidivorans CGMCC 1.7731^T by genome sequence screening. The e25 gene is 948 nucleotides in length and encodes a 315 amino acid protein (E25) with a predicted molecular mass of 33,683 Da. A phylogenetic tree revealed that E25 belongs to the hormone-sensitive lipase (HSL) family of lipolytic enzymes. An activity assay of E25 showed that it exhibited the highest catalytic efficiency when using p-nitrophenyl caproate (C6) as a substrate. The optimum pH and temperature were determined to be approximately pH 9 and 45°C, and the K_m and V_max values were 0.12 mM and 1,772 µmol/min/mg, respectively. After an incubation at 40°C for 80 min, E25 retained 75% of its basal activity. The enzyme exhibited good tolerance to metal cations, such as Ba²⁺, Ca²⁺, and Cu²⁺ (10 mM), but its activity was strongly inhibited by Co²⁺, Ni²⁺, Mn²⁺, and Zn²⁺. The E25 enzyme was stimulated by glycerol and retained over 60% of its basal activity in the presence of 1% Tween-80 and Triton X-100. Overall, the activity of E25 under alkaline conditions and its organic solvent and detergent tolerance indicate that E25 could be useful as a novel industrial catalyst in biotechnological applications.

Altererythrobacter xixiisoli sp. nov., isolated from wetland soil

A Gram-stain-negative, coccoid, yellow, non-motile, aerobic bacterium, designated strain S36T, was isolated from soil of the Xixi wetland in Zhejiang province, PR China. Phylogenetic analysis, based on 16S rRNA gene sequences, revealed that strain S36T could represent a novel species of genus Altererythrobacter showing highest similarity to Altererythrobacter atlanticus 26DY36T (96.31 % 16S rRNA gene sequence similarity). The temperature, pH and NaCl concentration ranges for growth were 10-37 °C (optimum 32 °C), pH 5.0-10.0 (optimum pH 7.0) and 0.5-3 % (optimum 1 %, w/v), respectively. The predominant respiratory quinone of strain S36T was Q-10. The major fatty acids were C16 : 0, C17 : 1ω6c, C18 : 1ω7c and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH). The G+C content of the genomic DNA was 62.7 mol%. These data all support the affiliation of strain S36T to the genus Altererythrobacter. The polar lipids profile of strain S36T comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, two unidentified phospholipids and two unidentified glycolipids. The results of physiological and biochemical tests allowed differentiation of strain S36T from other members of the genus Altererythrobacter. Therefore, strain S36T represents a novel species of the genus Altererythrobacter, for which the name Altererythrobacter xixiisoli sp. nov. is proposed; the type strain is S36T (=CGMCC 1.12804T=NBRC 110413T).

Altererythrobacter salegens sp. nov., a slightly halophilic bacterium isolated from surface sediment

A Gram-negative, rod-shaped and slightly halophilic bacterium, strain XY-R17T, was isolated from the surface sediment of Mai Po Inner Deep Bay Ramsar Site birdwatch in Hong Kong. The 16S rRNA gene sequence of strain XY-R17T exhibited 96.5 % similarity to that of the type strain of Altererythrobacter atlanticus. Optimal growth occurred at pH 7.0-7.5, 3-8 % (w/v) NaCl and at 30 °C. The major respiratory quinone was ubiquinone-10. The principal fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), 11-methyl C18 : 1ω7c and C17 : 1ω6c .The polar lipid profile consisted of the major compounds sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine and two unknown lipids. The DNA G+C content was 64.7 mol%. Based on its phenotypic properties, chemotaxonomic characteristics and phylogenetic distinctiveness, strain XY-R17T should be designated as a novel species of the genus Altererythrobacter. Therefore, the name Altererythrobacter salegens sp. nov. (type strain XY-R17T=KCTC 52267T=MCCC 1K01500T) is proposed.

Altererythrobacter lauratis sp. nov. and Altererythrobacter palmitatis sp. nov., isolated from a Tibetan hot spring

Two Gram-negative, moderately thermophilic, yellow-pigmented, rod-shaped and motile bacterial strains, designated YIM 75003^T and YIM 75004^T, were isolated from sediment samples collected from the Tagejia hot spring in Tibet, western China. The taxonomic affiliation of the two strains was investigated by a polyphasic approach. Pairwise comparison of the 16S rRNA gene sequences showed that strains YIM 75003^T and YIM 75004^T are closely related to Altererythrobacter buctense M0322^T (97.2 and 97.1% respectively), while sharing 99.9% sequence similarity against each other. Optimum growth of the two strains was observed at 37-45 °C, pH 8.0 and in the presence of 1-6% NaCl (w/v). Their predominant respiratory quinone was found to be ubiquinone 10. The major fatty acids in both the strains were identified as summed feature 8 (C_18:1 ω6c and/or C_18:1 ω7c) and summed feature 4 (C_17:1 anteiso B and/or iso I). Their major polar lipid profiles were found to be diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and sphingoglycolipid. The DNA G+C contents of strains YIM 75003^T and YIM 75004^T were determined to be 61.3 and 60.1 mol%, respectively. The DNA-DNA hybridization values between strains YIM 75003^T and YIM 75004^T, and between the two strains and their closely related phylogenetic neighbour A. buctense M0322^T (=CGMCC 1.12871^T) were less than 70%. Based on the morphological and physiological properties, phylogenetic analyses, chemotaxonomic characteristics and DNA-DNA relatedness values, the two strains can be distinguished from each other and from their phylogenetically closely related strain. Strains YIM 75003^T and YIM 75004^T are, therefore, considered to represent two novel species of the genus Altererythrobacter, for which the names Altererythrobacter lauratis sp. nov. (type strain YIM 75003^T = KCTC 52606^T = CCTCC AB2016268^T) and Altererythrobacter palmitatis sp. nov. (type strain YIM 75004^T = KCTC 52607^T = CCTCC AB2016270^T) are proposed.

Altererythrobacter soli sp. nov., isolated from desert sand

An alkaliphilic strain designed MN-1T was isolated from a desert sand sample collected from Tengger desert, north-western China. To delineate its taxonomic position, this Gram-stain-negative, rod-shaped, strictly aerobic bacterium was subjected to a polyphasic taxonomic study. Growth was observed at temperatures from 4 to 37 °C (optimum 30-32 °C), at salinities from 0 to 2 % (optimum 1 %) and at pH from 6.5 to 12.0 (optimum 7.0-9.0). Phylogenetic analysis based on 16S rRNA gene sequencing showed that strain MN-1T was a member of the genus Altererythrobacterbut could be distinguished from recognized species of this genus. Compared to the reference strains, the novel strain was flagellated and motile by means of polar flagella. The predominant respiratory quinone was ubiquinone-10 and the major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid, phosphatidylglycerol, phosphatidylcholine, one unidentified glycolipid, one unidentified phospholipid and four unidentified lipids. The predominant fatty acids were C18 : 1ω7c, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. These chemotaxonomic traits were in agreement with the characteristics of the genus Altererythrobacter. Strain MN-1T was most closely related to Altererythrobacter xinjiangensis S3-63T (96.9 % 16S rRNA gene sequence similarity), followed by Altererythrobacter dongtanensis JM27T (96.4 %) and Altererythrobacter marinus H32T (96.1 %). The G+C content of the genomic DNA of strain MN-1T was 67.0 mol%. On the basis of data from this polyphasic taxonomic study, strain MN-1T is proposed as the type strain of a novel species of the genus Altererythrobacter, named as Altererythrobacter soli sp. nov. (=KCTC 52135T=MCCC 1K02066T).

The Denitrification Characteristics and Microbial Community in the Cathode of an MFC with Aerobic Denitrification at High Temperatures

Microbial fuel cells (MFCs) have attracted much attention due to their ability to generate electricity while treating wastewater. The performance of a double-chamber MFC with simultaneous nitrification and denitrification (SND) in the cathode for treating synthetic high concentration ammonia wastewater was investigated at different dissolved oxygen (DO) concentrations and high temperatures. The results showed that electrode denitrification and traditional heterotrophic denitrification co-existed in the cathode chamber. Electrode denitrification by aerobic denitrification bacterium (ADB) is beneficial for achieving a higher voltage of the MFC at high DO concentrations (3.0–4.2 mg/L), while traditional heterotrophic denitrification is conducive to higher total nitrogen (TN) removal at low DO (0.5–1.0 mg/L) concentrations. Under high DO conditions, the nitrous oxide production and TN removal efficiency were higher with a 50 Ω external resistance than with a 100 Ω resistance, which demonstrated that electrode denitrification by ADB occurred in the cathode of the MFC. Sufficient electrons were inferred to be provided by the electrode to allow ADB survival at low carbon:nitrogen ratios (≤0.3). Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) results showed that increasing the DO resulted in a change of the predominant species from thermophilic autotrophic nitrifiers and facultative heterotrophic denitrifiers at low DO concentrations to thermophilic ADB at high DO concentrations. The predominant phylum changed from Firmicutes to Proteobacteria, and the predominant class changed from Bacilli to Alpha, Beta, and Gamma Proteobacteria.

Description of Altererythrobacter aerius sp. nov., isolated from air, and emended description of the genus Altererythrobacter

A Gram-stain-negative, yellow-pigmented, ovoid to rod-shaped, strictly aerobic bacterial strain, designated 100921-2T, was isolated from air at the foot of Xiangshan Mountain. Phylogenetic and phenotypic analysis of the organism revealed that the isolate belongs to the genus Altererythrobacter. Strain 100921-2T showed high 16S rRNA gene sequence similarity (96.01-94.70 %) to other type strains of the genus Altererythrobacter, with the highest similarity to Altererythrobactermarensis MSW-14T. Growth of strain 100921-2T was observed at 4-50 °C (optimum, 30 °C), at pH 4.5-10.0 (optimum, pH 7.0) and at salinities of 0-10 % (w/v) NaCl (optimum 0-0.5 %). The major fatty acids were C18 : 1ω7c (27.8 %), C17 : 1ω6c (23.1 %), 11-methyl C18 : 1ω7c(11.9 %), summed feature 3 (9.1 %) and C15 : 0 2-OH (7.9 %). The predominant respiratory quinone was ubiquinone-10 (Q-10). Polar lipid analysis indicated the presence of diphosphatidylglycerol, sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, two unknown phospholipids, five unknown polar lipids and two unknown glycolipids. The DNA G+C content of the type strain was 67.5 mol%. On the basis of the data from the polyphasic characterization, strain 100921-2T represents a novel species, for which the name Altererythrobacter aerius sp. nov. is proposed. The type strain is 100921-2T (=CFCC 14287T=KCTC 42844T).