Emticicia sediminis sp. nov. isolated from sediment of a shallow stream

Emticicia fluvialis sp. nov., a potential hormone-degrading bacterium isolated from Nakdong River, Republic of Korea

A novel species of the genus Emticicia, designated BHSR1T, was isolated from a water sample that was collected from the Nakdong River, Republic of Korea, and its taxonomic affiliation was studied using a polyphasic approach. This bacterium was Gram-stain-negative, non-motile, aerobic, curved, rod-shaped, and oxidase- and catalase-negative. The bacterium grew optimally at 37 °C, pH 7.5 and 0% (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain BHSR1T should be affiliated with the genus Emticicia, with a high similarity to Emticicia fontis KCTC 52248T (98.10%). Phylogenomic analysis also suggested that the strain represents a novel species in the genus Emticicia. The genomic G + C content was 41.9%. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization between strain BHSR1T and its closely related relatives in the genus Emticicia were in ranges of 71.1-75.8%, 69.4-77.5% and 18.6-19.9%, respectively. The gene cluster within BHSR1T contained genes encoding enzymes that could be involved in hormone degradation. The major cellular fatty acids (> 10%) were summed feature 3 (comprising C16:1ω6c and/or C16:1ω7c) and iso-C15:0. With regards to the polar lipid profile, phosphatidylethanolamine (PE), two unidentified aminolipids and three unidentified lipids were identified as the major compounds. The major respiratory quinone was menaquinone (MK)-7. Based on its phylogenetic, phenotypic, chemotaxonomic, and genomic features, strain BHSR1T should be considered a novel species in the genus Emticicia of the family Spirosomaceae, for which the name Emticicia fluvialis sp. nov. is proposed. The type strain was considered BHSR1T (= KCTC 92622T = GDMCC 1.3740T).

Emticicia agri sp. nov., a novel member of the family Cytophagaceae

A bacterial strain, 17J42-9^T, was isolated from a soil sample collected on Jeju Island, Republic of Korea. Cells were observed to be Gram-stain negative and rod-shaped. Colonies were observed to be orange in colour on R2A agar. Analysis of 16S rRNA gene sequences showed that high levels of 16S rRNA sequence similarity were shared between 17J42-9^T and Emticicia fontis IMCC1731^T (98.2 %), Emticicia ginsengisoliGsoil 085^T (98.2 %) and Emticicia soli ZZ-4^T (97.8 %). Growth of strain 17J42-9^T was observed at 10-37 °C, pH 6.0-8.5 and in the presence of 0-0.5 % NaCl. The genomic G+C content was calculated to be 38.6 mol%. The predominant respiratory quinone of the isolate was found to be MK-7; the major fatty acids were identified as summed feature 3 (C_16 : 1 ω7c and/or C_16 : 1 ω6c) (34.1 %), C_15 : 0iso (23.4 %) and C_17 : 0iso 3-OH (10.8 %). The major polar lipids were found to be phosphatidylethanolamine, two unidentified aminolipids and an unidentified lipid. The phenotypic and chemotaxonomic data support the affiliation of strain 17J42-9^T with the genus Emticicia. However, the DNA-DNA relatedness between the isolate and its closest phylogenetic neighbours was lower than 46 %. The results of 16S rRNA gene sequence similarity analysis, DNA-DNA hybridization analysis and the observed differentiating phenotypic properties from other closely related taxa clearly indicate that strain 17J42-9^T represents a novel species in the genus Emticicia, for which the name Emticiciaagri sp. nov. is proposed. The type strain is 17J42-9^T (=KCTC 62270^T=JCM 33056^T).

Enhanced production of biomass and lipids by Euglena gracilis via co-culturing with a microalga growth-promoting bacterium, Emticicia sp. EG3

BACKGROUND

Euglena gracilis, a unicellular flagellated microalga, is regarded as one of the most promising species as microalgal feedstock for biofuels. Its lipids (mainly wax esters) are suitable for biodiesel and jet fuel. Culture of E. gracilis using wastewater effluent will improve the economics of E. gracilis biofuel production. Enhancement of the productivity of E. gracilis biomass is critical to creating a highly efficient biofuels production system. Certain bacteria have been found to promote microalgal growth by creating a favorable microenvironment. These bacteria have been characterized as microalgae growth-promoting bacteria (MGPB). Co-culture of microalgae with MGPB might offer an effective strategy to enhance microalgal biomass production in wastewater effluent culture systems. However, no MGPB has been identified to enhance the growth of E. gracilis. The objectives of this study were, therefore, to isolate and characterize the MGPB effective for E. gracilis and to demonstrate that the isolated MGPB indeed enhances the production of biomass and lipids by E. gracilis in wastewater effluent culture system.

RESULTS

A bacterium, Emticicia sp. EG3, which is capable of promoting the growth of microalga E. gracilis, was isolated from an E. gracilis-municipal wastewater effluent culture. Biomass production rate of E. gracilis was enhanced 3.5-fold and 3.1-fold by EG3 in the co-culture system using a medium of heat-sterilized and non-sterilized wastewater effluent, respectively, compared to growth in the same effluent culture but without EG3. Two-step culture system was examined as follows: E. gracilis was cultured with or without EG3 in wastewater effluent in the first step and was further grown in wastewater effluent in the second step. Production yields of biomass and lipids by E. gracilis were enhanced 3.2-fold and 2.9-fold, respectively, in the second step of the system in which E. gracilis was co-cultured with EG3 in the first step.

CONCLUSION

Emticicia sp. EG3 is the first MGPB for E. gracilis. Growth-promoting bacteria such as EG3 will be promising agents for enhancing E. gracilis biomass/biofuel productivities.

Emticicia soli sp. nov., a novel member of the family 'Flexibacteraceae', isolated from tetrabromobisphenol A-contaminated soil

Bacterial strain ZZ-4T, a Gram-stain-negative, aerobic, non-spore-forming, non-motile, non-flagellated, rod-shaped bacterium, was isolated from tetrabromobisphenol A-contaminated soil in PR China. The taxonomic position of this strain was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain ZZ-4T was a member of the genus Emticicia and showed the highest sequence similarity to Emticicia fontis IMCC1731T (98.0 %) and Emticicia ginsengisoli Gsoil 085T (97.2 %), and lower (<97 %) sequence similarity to other known Emticicia species. Chemotaxonomic analysis revealed that strain ZZ-4T possessed menaquinone MK-7 as the major isoprenoid quinone; and iso-C15 : 0, summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7), iso-C17 : 0 3-OH and C16 : 1ω5c were the predominant fatty acids. Strain ZZ-4T showed low DNA-DNA relatedness with E. fontis IMCC1731T (39.8±3.1 %) and E. ginsengisoli Gsoil 085T (44.51±1.5 %). The DNA G+C content was 38.3 mol%. Based on the phylogenetic and phenotypic characteristics, chemotaxonomic data and DNA-DNA hybridization results, strain ZZ-4T is considered to represent a novel species of the genus Emticicia, for which the name Emticicia soli sp. nov. is proposed. The type strain is ZZ-4T (=KCTC 52344T=CCTCC AB 2016137T).

Arcticibacterium luteifluviistationis gen. nov., sp. nov., isolated from Arctic seawater

A Gram-staining-negative, aerobic, non-motile and yellow-pigmented bacterium, designated strain SM1504T, was isolated from Arctic seawater. It hydrolysed aesculin and gelatin but did not reduce nitrate to nitrite. Phylogenetic analysis of 16S rRNA gene sequences revealed that strain SM1504T constituted a distinct phylogenetic line within the family Cytophagaceae and was closely related to species of the genera Lacihabitans, Emticicia, Fluviimonas and Leadbetterella, with respect to which low sequence similarities between 88.9 and 91.6 % were observed. The major fatty acids of strain SM1504T were summed feature 3 (comprising C16 : 1ω7c and/or iso-C15 : 0 2-OH) and iso-C15 : 0. The predominant polar lipids of strain SM1504T were phosphatidylethanolamine and one unidentified lipid. The only respiratory quinone detected in strain SM1504T was MK7. The DNA G+C content of strain SM1504T was 40.8 mol%. On the basis of the phylogenetic, chemotaxonomic and phenotypic characterization in this study, strain SM1504T is considered to represent a novel species in a new genus of the family Cytophagaceae, for which the name Arcticibacterium luteifluviistationis gen. nov., sp. nov. is proposed. The type strain is SM1504T (=KCTC 42716T=CCTCC AB 2015348T).

Emticicia aquatilis sp. nov., isolated from a freshwater sample

A Gram-stain-negative, facultatively anaerobic, non-motile, rod-shaped and yellow-pigmented bacterium, designated strain THG-DN6.14T, was isolated from a freshwater sample near Donghaksa temple in Daejeon, South Korea. On the basis of the results of 16S rRNA gene sequence comparisons, THG-DN6.14T was found to be most closely related to Emticicia sediminis JBR12T (99.1 % sequence similarity), Emticicia oligotrophica DSM 17448T (97.6 %), Emticicia aquatica HMF2925T (96.5 %), and Emticicia ginsengisoliGsoil 085T (94.4 %). The DNA-DNA relatedness between THG-DN6.14T and its phylogenetically closest neighbours was below 65.0 %. The DNA G+C content was 43.3 mol%. The major polar lipids were found to be phosphatidylethanolamine, an unidentified glycolipid and an unidentified aminoglycolipid. The major fatty acids were identified as C16 : 0, iso-C15 : 0, iso-C17 : 0 3-OH, and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The respiratory quinone was menaquinone MK-7. These data supported the affiliation of THG-DN6.14T to the genus Emticicia. THG-DN6.14Tcould be distinguished from related species of the genus Emticicia by physiological and biochemical tests. Therefore, the novel isolate represents a novel species, for which the name Emticicia aquatilis sp. nov. is proposed, with THG-DN6.14T (=KACC 18540T=CGMCC 1.15958T) as the type strain.

Emticiciafontis sp. nov., isolated from a freshwater pond

A bacterial strain, designated IMCC1731T, was isolated from an eutrophic freshwater pond and characterized using a polyphasic taxonomic approach. Cellular growth occurred at pH 6-9 (optimum, pH 8.0), at 10-30 °C (optimum, 25 °C) and with 0-1 % (w/v) NaCl (optimum, 0 %). Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain IMCC1731T belonged to the genus Emticicia in the family Cytophagaceae and was most closely related to Emticicia ginsengisoli Gsoil 085T (98.1 %) followed by Emticicia paludis HMF3850T (95.0 %), Emticicia oligotrophica DSM 17448T (94.7 %), Emticicia aquatica HMF2925T (94.4 %) and Emticicia sediminis JBR12T (94.0 %). The DNA-DNA relatedness between strain IMCC1731T and E. ginsengisoli Gsoil 085T was 47±4 %. The DNA G+C content of strain IMCC1731T was 37.7 mol%. The predominant cellular fatty acids were summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c) and iso-C15 : 0. Based on the physiological and chemotaxonomic characteristics, DNA-DNA relatedness and 16S rRNA gene phylogeny, stain IMCC1731T is considered to represent a novel species of the genus Emticicia, for which the name Emticicia fontis sp. nov. is proposed. The type strain is IMCC1731T (=KCTC 52248T=JCM 31373T).

Comparative analysis of bacteria associated with different mosses by 16S rRNA and 16S rDNA sequencing

To understand the differences of the bacteria associated with different mosses, a phylogenetic study of bacterial communities in three mosses was carried out based on 16S rDNA and 16S rRNA sequencing. The mosses used were Hygroamblystegium noterophilum, Entodon compressus and Grimmia montana, representing hygrophyte, shady plant and xerophyte, respectively. In total, the operational taxonomic units (OTUs), richness and diversity were different regardless of the moss species and the library level. All the examined 1183 clones were assigned to 248 OTUs, 56 genera were assigned in rDNA libraries and 23 genera were determined at the rRNA level. Proteobacteria and Bacteroidetes were considered as the most dominant phyla in all the libraries, whereas abundant Actinobacteria and Acidobacteria were detected in the rDNA library of Entodon compressus and approximately 24.7% clones were assigned to Candidate division TM7 in Grimmia montana at rRNA level. The heatmap showed the bacterial profiles derived from rRNA and rDNA were partly overlapping. However, the principle component analysis of all the profiles derived from rDNA showed sharper differences between the different mosses than that of rRNA-based profiles. This suggests that the metabolically active bacterial compositions in different mosses were more phylogenetically similar and the differences of the bacteria associated with different mosses were mainly detected at the rDNA level. Obtained results clearly demonstrate that combination of 16S rDNA and 16S rRNA sequencing is preferred approach to have a good understanding on the constitution of the microbial communities in mosses.

Emticicia paludis sp. nov., isolated from wetland freshwater

A novel bacterium, designated HMF3850T, was isolated from freshwater collected from the Gyeong-an wetland, Republic of Korea. Cells were Gram-stain-negative, aerobic, straight rods, non-motile, and oxidase- and catalase-positive. Growth was observed at pH 6.0-8.0 and at 10-30 °C on R2A agar. Comparative analysis of 16S rRNA gene sequences revealed that strain HMF3850T is a member of the genus Emticicia, sharing highest sequence similarities with Emticicia aquatica HMF2925T (96.7 % 16S rRNA gene sequence similarity), Emticicia sediminis JBR12T (95.0 %), Emticicia ginsengisoliGsoil 085T (94.9 %) and Emticicia oligotrophica DSM 17448T (94.7 %). The major fatty acids were iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The predominant respiratory quinone was MK-7. The major polar lipids were phosphatidylethanolamine, phosphatidylinositol, one unidentified aminophospholipid, two unidentified aminolipids and eight unidentified polar lipids. The DNA G+C content was 38.5 mol %. On the basis of the evidence presented in this study, strain HMF3850T represents a novel species of the genus Emticicia, for which the name Emticicia paludis sp. nov. is proposed. The type strain is HMF3850T (=KCTC 42851T=CECT 9087T).