Sunxiuqinia elliptica

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Sunxiuqinia elliptica gen. nov., sp. nov.

Three isolates: DQHS4xT, DQHS8, DQHS15

Higher order taxa

Bacteria, Bacterioidetes/Chlorobi group, Bacteroidetes, unclassified Bacteroidetes


Genus species: elliptica

Description and Significance

Cells are strictly anaerobic, non-motile, Gram-negative, elliptical (0.4 x 0.8-0.9 μm), oxidase and catalase negative, alkaline phosphate positive. After 2-3 days, growth appeared on agar plates under aerobic conditions. Colonies were whitish to slightly pink, 1-3 mm in diameter, convex and smooth. After 4-5 days, colonies quickly changed color to orange-red. Colonies were not formed under anoxic conditions on any medium even after 2 weeks. Flexirubin pigments are not formed.

16S rRNA gene sequence analysis found that the three isolates shared very low sequence similarity (<90%) to all described species of the phylum Bacteroidetes. The closest relative of the isolates was Prolixibacter bellariivorans F2xT, sharing only 89.6 % sequence similarity. Based on the results of a polyphasic taxonomic analysis, they are considered to represent a novel species and genus of the phylum Bacteroidetes. Results from DNA-DNA hybridization experiments suggest that the strains constitute a single species; a 0.85% relatedness was revealed between the three isolates. Due to these results, the three strains are considered to represent a novel species of a new genus in the phylum Bacteroidetes, for which the name Sunxiuqinia elliptica gen. nov., sp. nov. is proposed.

Cell Metabolism

The major cellular fatty acids are iso-C17:0 3-OH (19.8–20.0 %), iso-C15:0 (16.9–17.3 %), anteiso-C17:1 B and/or iso-C17:1 I (7.4–8.7 %), C17:0 2-OH (8.4 %), anteiso-C15:0 (8.2–8.6 %) and C17:1ω6c (5.6–6.0 %).

The major respiratory quinone is menaquinone-7 (MK-7).

DNA G+C contents of the three strains: DQHS4xT – 43.4 mol%; DQHS8 – 41.8 mol%; DQHS15 – 42.1 mol%.

The following carbohydrates can be used as sole carbon sources: D-fructose, L-rhamnose, D-xylose, myo-inositol, sorbitol, trehalose, D-mannitol, ribose, raffinose, gluconate, malonate and propionate.


In API 50CH tests, acid is produced from L-arabinose, D-ribose, D-xylose, adonitol, methyl b-xyloside, L-rhamnose, D-mannitol, methyl a-D-mannoside, methyl a- D-glucoside, N-acetylglucosamine, amygdalin, arbutin, aes- culin, D-salicin, cellobiose, melibiose, sucrose, trehalose, melezitose, raffinose, starch, glycogen, gentiobiose, turanose, L-fucose and 5-ketogluconate.

Antibiotic Sensitivity and Resistance

Sensitive to (mg per disc, unless otherwise indicated) doxycycline (30), erythromycin (15), novobiocin (30), rifampicin (5), lincomycin (2), clindamycin (2) and chloramphenicol (30).

Resistant to ampicillin (10), carbenicillin (100), cefalexin (30), cipro-floxacin (5), kanamycin (30), nalidixic acid (30), neomycin (30), penicillin G (10 IU), streptomycin (10), tetracycline (30), oxacillin (1), polymyxin B (300 IU) and vancomycin (30).

Native Environment

Bacteria that belong to the phylum Bacteroidetesare considered to be important to aquatic environments, as well as displaying a worldwide distribution in marine and freshwater ecosystems.

Strains were isolated from sediment of a seashore pond home to sea cucumber culture at Jimo, Qingdao, located on the east coast of China (depth 10m; 36.50º N 120.82º E).

The three strains grow at 15–42ºC (optimum 30ºC), at a pH between 5–9 (optimum pH 7–8), with an NaCl concentration between 0.5 and 10% (optimum 3%).

Other Microbes Found in the Same or Similar Environments

Both found in seafloor sediment.

Sunxiuqinia faeciviva

Found in deep sub-seafloor sediment at a depth of 247.1m below the sea floor off the coast of the Shimokita Peninsula of Japan, in the north western Pacific Ocean. It is a facultatively anaerobic organoheterotroph of the Bacteroidetes family. Has gliding motility with thin, long rods with peritrichous fimbriae like structures. Grows at temperatures between 4-37ºC (optimal 30ºC); pH between 5.4-8.3 (optimal 7.5); 5-60g NaCl lx-1 (optimum 20-25g). G+C content is 43.2 mol%. 16S rRNA gene sequence similarity to S. elliptica is 95.5%. Strain JAM-BA0302xT

Sunxiuqinia dokdonensis

Found in deep sub-seafloor sediment at a depth of 900m below the sea floor off Seo-do in the East Sea of the Republic of Korea. It's a novel facultative anaerobe made motile by gliding; cells are Gram negative, spore forming rods. Optimal growth occurs at 30ºC, at a pH of 7, and at 0.5-7.0% NaCl. G+C content is 40.9 mol%. 16S rRNA gene sequence similarity to S. elliptica is 96.3%; sequence similarity to S. faeciviva is 97.9%. Strain DH1T.


Chang, D., Lee, J., Lee, G., Rhee, M., Lee, H., Bae, K. S., Park, D., & Kim, B. (2013). Sunxiuqinia dokdonensis sp. nov., isolated from deep sub-seafloor sediment. Journal of Microbiology, 51(6), 741-746. doi: 10.1007/s12275-013-3492-z

Takai, K., Abe, M., Miyazaki, M., Koide, O., Nunoura, T., Imachi, H., Inagaki, F., & Kobayashi, T. (2014). Sunxiuqinia faeciviva sp. nov., a facultatively anaerobic organoheterotroph of the Bacteroidetes isolated from deep subseafloor sediment. International Journal of Systematic and Evolutionary Microbiology, 63(Pt. 5), 1602-1609. doi: 10.1099/ijs.0.044065-0

Qu, L., Zhu, F., Hong, X., Gao, W., Chen, J., & Sun, X. (2011). Sunxiuqinia elliptica gen. nov., sp. nov., a member of the phylum Bacteroidetes isolated from sediment in a sea cucumber farm. International Journal of Systematic and Evolutionary Microbiology, 61(12), 2885-2889. doi: 10.1099/ijs.0.026971-0

Edited by Sydney Bradshaw, student of Rachel Larsen at the University of Southern Maine