Microbulbifer bruguierae sp. nov., isolated from sediment of mangrove plant Bruguiera sexangula, and comparative genomic analyses of the genus Microbulbifer

A Gram-negative, non-motile, strictly aerobic, rod-shaped bacterium, designated as H12T, was isolated from the sediments of mangrove plant Bruguiera sexangula taken from Dapeng district, Shenzhen, PR China. The pairwise 16S rRNA gene sequence analysis showed that strain H12T shared high identity levels with species of the genus Microbulbifer, with the highest similarity level of 98.5 % to M. pacificus SPO729T, followed by 98.1 % to M. donghaiensis CN85T. Phylogenetic analysis using core-genome sequences showed that strain H12T formed a cluster with type species of M. pacificus SPO729T and M. harenosus HB161719T. The complete genome of strain H12T was 4 481 396 bp in size and its DNA G+C content was 56.7 mol%. The average nucleotide identity and digital DNA-DNA hybridization values among strain H12T and type species of genus Microbulbifer were below the cut-off levels of 95-96 and 70 %, respectively. The predominant cellular fatty acids of strain H12T were iso-C15 : 0 (22.5 %) and C18 : 1  ω7c (13.9 %). Ubiquinone-8 was detected as the major respiratory quinone. The polar lipids of strain H12T comprised one phosphatidylglycerol, one phosphatidylethanolamine, one unidentified aminoglycophospholipid, one unidentified glycophospholipid, three unidentified glycolipids, two unidentified aminolipids, and one unidentified lipid. Based on polyphasic evidence, strain H12T represents a novel species of the genus Microbulbifer, for which the name Microbulbifer bruguierae sp. nov. is proposed. The type strain is H12T (=KCTC 92859T=MCCC 1K08451T). Comparative genomic analyses of strain H12T with strains of the genus Microbulbifer reveal its potential in degradation of pectin.

Microbulbifer okhotskensis sp. nov., isolated from a deep bottom sediment of the Okhotsk Sea

A Gram-negative, aerobic, non-motile bacterium КMM 9862^T was isolated from a deep bottom sediment sample obtained from the Okhotsk Sea, Russia. Based on the 16S rRNA gene and whole genome sequences analyses the novel strain КMM 9862^T fell into the genus Microbulbifer (class Gammaproteobacteria) sharing the highest 16S rRNA gene sequence similarities of 97.4% to Microbulbifer echini AM134^T and Microbulbifer epialgicus F-104^T, 97.3% to Microbulbifer pacificus SPO729^T, 97.1% to Microbulbifer variabilis ATCC 700307^T, and similarity values of < 97.1% to other recognized Microbulbifer species. The average nucleotide identity and digital DNA-DNA hybridization values between strain КMM 9862^T and M. variabilis ATCC 700307^T and M. thermotolerans DSM 19189^T were 80.34 and 77.72%, and 20.2 and 19.0%, respectively. Strain КMM 9862^T contained Q-8 as the predominant ubiquinone and C_16:0, C_16:1 ω7c, C_12:0, and C_10:0 3-OH as the major fatty acids. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, an unidentified aminophospholipid, an unidentified aminolipid, two unidentified phospholipids, phosphatidic acid, and an unidentified lipid. The DNA G+C content of 49.8% was calculated from the genome sequence. On the basis of the phylogenetic evidence and distinctive phenotypic characteristics, the marine bacterium KMM 9862^T is proposed to be classified as a novel species Microbulbifer okhotskensis sp. nov. The type strain of the species is strain KMM 9862^T (= KACC 22804^T).

Microbulbifer hainanensis sp. nov., a moderately halopilic bacterium isolated from mangrove sediment

A new bacterium was successfully isolated from a mangrove sediment sample in Haikou City, Hainan Province, China. The organism is a Gram-negative, rod-shaped, non-motile and strictly aerobic bacterium, named NBU-8HK146^T. Strain NBU-8HK146^T was able to grow at temperatures of 10-40 °C, at salinities of 0-11% (w/v) and at pH 5.5-9.5. Veoges-Proskauer, methyl red reaction and hydrolysis of Tween 20 were negative. Catalase and oxidase activities, H₂S production, hydrolysis of starch, casein, Tweens 40, 60 and 80 were positive. The major cellular fatty acids were C_16:0, iso-C_15:0 and summed feature 9. The major respiratory quinone was ubiquinone-8 (Q-8). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and two unidentified glycolipids. According to 16S rRNA gene sequence similarities, strain NBU-8HK146^T shared 98.0%, 97.9%, 97.7%, 97.6% and 97.3% similarities to the species with validated name Microbulbifer taiwanensis CC-LN1-12^T, Microbulbifer rhizosphaerae Cs16b^T, Microbulbifer marinus Y215^T, Microbulbifer donghaiensis CN85^T and Microbulbifer aggregans CCB-MM1^T, respectively. Phylogenetic analyses indicated that strain NBU-8HK146^T formed a distinct lineage with strains Microbulbifer taiwanensis CC-LN1-12^T and Microbulbifer marinus Y215^T. Both digital DNA-DNA hybridization values (19.5-22.7%) and average nucleotide identity values (73.2-78.9%) between strain NBU-8HK146^T and related species of genus Microbulbifer were below the species delineation cutoffs. The DNA G+C content was 58.9 mol%. Many proteins involving in the adaption of osmotic stress in the salt environment of mangrove were predicted in genome of strain NBU-8HK146^T. From phenotypic, genotypic, phylogenetic and chemotaxonomic characteristics, strain NBU-8HK146^T can be regarded as a new Microbulbifer species for which the name Microbulbifer hainanensis. The type strain is NBU-8HK146^T (= KCTC 82226^T = MCCC 1K04737^T).

Microbulbifer harenosus sp. nov., an alginate-degrading bacterium isolated from coastal sand

A Gram-stain-negative, aerobic, rod-shaped bacterium with peritrichous flagella, designated strain HB161719^T, was isolated from coastal sand collected from Tanmen Port in Hainan, PR China. The isolate was found to grow with 2-11 % (w/v) NaCl, at 15-45 °C and pH 6.0-10.0, with an optima of 2-3 % NaCl, 37 °C and pH 7.0, respectively. Chemotaxonomic analysis showed that Q-8 was detected as the sole respiratory quinone and that iso-C_15 : 0 and summed features 3, 8 and 9 were the major cellular fatty acids. The G+C content of the genomic DNA was 58.2 mol%. Analysis of the 16S rRNA gene sequence of the strain showed an affiliation with the genus Microbulbifer, sharing 98.7, 98.4, 97.8 and 97.8 % sequence similarities to the closest relatives of Microbulbifer okinawensis ABABA23^T, Microbulbifer pacificus SPO729^T, Microbulbifer taiwanensis CC-LN1-12^T and Microbulbifer gwangyangensis GY2^T, respectively. Low DNA-DNA hybridization values showed that it formed a distinct genomic species. The combined phenotypic and molecular features supported that strain HB161719^T represents a novel species of the genus Microbulbifer, for which the name Microbulbifer harenosus sp. nov. is proposed. The type strain is HB161719^T (=CGMCC 1.13584^T=JCM 32688^T).

Microbulbifer echini sp. nov., isolated from the gastrointestinal tract of a purple sea urchin, Heliocidaris crassispina

A novel bacterium, designated as strain AM134T, was isolated from the gut of a purple sea urchin (Heliocidaris crassispina) gathered from the coastal waters of Dokdo, Korea. Strain AM134T was Gram-stain-negative, both catalase- and oxidase-positive, strictly aerobic and showed a rod-coccus cell cycle. Optimum growth occurred at 30 °C, in the presence of 2 % (w/v) NaCl and at pH 7. The 16S rRNA gene sequence analysis showed that strain AM134T belonged to the genus Microbulbifer in the family Alteromonadaceae and had high 16S rRNA gene sequence similarity (>97 %) with Microbulbifer epialgicus F-104T (98.9 % similarity) and Microbulbifer variabilis Ni-2088T (98.6 % similarity). The polar lipid profile of strain AM134T was composed of phosphatidylethanolamine, phosphatidylserine, three unidentified aminophospholipids, two unidentified phospholipids, an unidentified amino lipid and six unidentified lipids. The major respiratory quinone was identified as ubiquinone-8 (Q-8). The major cellular fatty acids were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) and C16 : 0. The DNA-DNA hybridization analysis showed that the strain shared less than 28 % genomic relatedness with Microbulbifer epialgicus DSM 18651T (27±3 %) and Microbulbifer variabilis ATCC 700307T (15±1 %). The G+C content of the genomic DNA was 56.1 mol%. The results of the phylogenetic, phenotypic and genotypic analyses suggest that strain AM134T represents a novel species in the genus Microbulbifer, for which the name Microbulbifer echini is proposed. The type strain is AM134T (=KACC 18258T=JCM 30400T).

Effect of different salinity adaptation on the performance and microbial community in a sequencing batch reactor

The performance and microbial community profiles in a sequencing batch reactor (SBR) treating saline wastewater were studied over 300days from 0wt% to 3.0wt% salinity. The experimental results indicated that the activated sludge had high sensitivity to salinity variations in terms of pollutants removal and sedimentation. At 2.0wt% salinity, the system retained a good performance, and 95% removal rate of chemical oxygen demand (COD), biochemical oxygen demand (BOD), NH4(+)-N and total phosphorus (TP) could be achieved. Operation before addition salinity revealed the optimal performance and the most microbial diversity indicated by 16S rRNA gene clone library. Sequence analyses illustrated that Candidate_division_TM7 (TM7) was predominant at 2.0 wt% salinity; however, Actinobacteria was more abundant at 3.0wt% salinity.

A taxonomic framework for emerging groups of ecologically important marine gammaproteobacteria based on the reconstruction of evolutionary relationships using genome-scale data

In recent years a large number of isolates were obtained from saline environments that are phylogenetically related to distinct clades of oligotrophic marine gammaproteobacteria, which were originally identified in seawater samples using cultivation independent methods and are characterized by high seasonal abundances in coastal environments. To date a sound taxonomic framework for the classification of these ecologically important isolates and related species in accordance with their evolutionary relationships is missing. In this study we demonstrate that a reliable allocation of members of the oligotrophic marine gammaproteobacteria (OMG) group and related species to higher taxonomic ranks is possible by phylogenetic analyses of whole proteomes but also of the RNA polymerase beta subunit, whereas phylogenetic reconstructions based on 16S rRNA genes alone resulted in unstable tree topologies with only insignificant bootstrap support. The identified clades could be correlated with distinct phenotypic traits illustrating an adaptation to common environmental factors in their evolutionary history. Genome wide gene-content analyses revealed the existence of two distinct ecological guilds within the analyzed lineage of marine gammaproteobacteria which can be distinguished by their trophic strategies. Based on our results a novel order within the class Gammaproteobacteria is proposed, which is designated Cellvibrionales ord. nov. and comprises the five novel families Cellvibrionaceae fam. nov., Halieaceae fam. nov., Microbulbiferaceae fam. nov., Porticoccaceae fam. nov., and Spongiibacteraceae fam. nov.

Gilvimarinus polysaccharolyticus sp. nov., an agar-digesting bacterium isolated from seaweed, and emended description of the genus Gilvimarinus

A taxonomic study was carried out on strain YN3(T), which was isolated from a seaweed sample taken from the coast of Weihai, China. The bacterium was Gram-stain-negative, rod-shaped, and could grow at pH 5.0-10.0 and 4-32 °C in the presence of 0-9.0 % (w/v) NaCl. Strain YN3(T) was positive for the hydrolysis of polysaccharides, such as agar, starch and xylan. The predominant respiratory quinone was ubiquinone-8. The major fatty acids were C16 : 1ω7c and/or iso-C15 : 0 2-OH, C16 : 0 and C18 : 1ω7c. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine, and two unidentified glycolipids. The genomic DNA G+C content was 49.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YN3(T) should be assigned to the genus Gilvimarinus. 'Gilvimarinus agarilyticus' KCTC 23325 and Gilvimarinus chinensis QM42(T) had the closest phylogenetic relationship to strain YN3(T), and showed 97.9 % and 95.8 % sequence similarities, respectively. On the basis of phenotypic, chemotaxonomic and genotypic data and DNA-DNA hybridization studies, we propose that strain YN3(T) represents a novel species of the genus Gilvimarinus, for which the name Gilvimarinus polysaccharolyticus sp. nov. is proposed. The type strain is YN3(T) ( = KCTC 32438(T) = JCM 19198(T)). An emended description of the genus Gilvimarinus is also presented.

Defluviimonas aestuarii sp. nov., a marine bacterium isolated from a tidal flat, and emended description of the genus Defluviimonas Foesel et al. 2011

A novel Gram-staining-negative, strictly aerobic bacterium, designated BS14(T), was isolated from a marine tidal flat of the South Sea in Korea. Colonies were opaque, white, smooth and circular on marine agar. Cells were moderately halophilic, non-motile rods showing catalase- and oxidase-positive reactions. Growth of strain BS14(T) was observed at 5-40 °C (optimum: 30 °C), pH 6.5-9.5 (optimum: 7.0-7.5) and 0-10 % (w/v) NaCl (optimum: 1-1.5 %). The G+C content of the genomic DNA was 61.6 mol%. Strain BS14(T) contained ubiquinone-10 (Q-10) as the sole respiratory quinone and summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1ω6c), C18 : 0 3-OH, C10 : 0 3-OH and C18 : 0 as the major fatty acids. The polar lipid pattern comprised phosphatidylethanolamine, diphosphatidylglycerol, an unidentified aminolipid, an unidentified phospholipid and an unidentified polar lipid. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain BS14(T) formed a tight phylogenetic lineage with Defluviimonas denitrificans D9-3(T) with a bootstrap value of 100 %. The 16S rRNA gene sequence similarity between strain BS14(T) and D. denitrificans D9-3(T) was 97.4 % and their DNA-DNA relatedness was 19.1 ± 3.6 %. Based on the phenotypic and genotypic studies, strain BS14(T) represents a novel species of the genus Defluviimonas, for which the name Defluviimonas aestuarii sp. nov. is proposed. The type strain is BS14(T) (= KACC 16442(T) = JCM 18630(T)). An emended description of the genus Defluviimonas Foesel et al. 2011 is also proposed.