Genus nameThiothrix
Alternative namesEikelboom Type 021N group I, II, III
NCBI taxonomy ID1030



16S gene copy number2-4

 In situOther
Hydrophobic cell surface10

Identification of Thiothrix by fluorescence in situ hybridization (FISH). A. Phase-contrast micrograph showing a filament with sulphur (S) globules. B. The same filament without S globules after ethanol treatment. C. The same filament after hybridization with the probe for gamma Proteobacteria labelled with FLUOS. D. The same filament after hybridization with the specific Thiothrix probe labelled with Cy3. Bar= 5 microns. - Source:3

Aerobic heterotroph
Nitrite reduction
Fatty acids
Proteins/Amino acids

POSNEGVariableNot assessed


Thiothrix are filamentous organisms, some of which have the Eikelboom type 021N morphotype 4. Ocassionally abundant in municiple activated sludge plants with nutrient removal but common in industrial plants. Has been associated with severe bulking problems and occasionally foaming 3. They are aerobic heterotrophs, which can also exhibit mixotrophic and chemolithoautotrophic activity under aerobic conditions 3 5. Bacteria in this genus can oxidize reduced sulfur compounds, namely sulfide and thiosulfate, and produce intracellular sulfur globules when grown in the presence of these 3. Most Thiothrix with the type 021N morphology do not reduce sulfur under anaerobic conditions 3. In situ the organism is physiologically active with nitrate as an electron acceptor under anaerobic conditions, although it is unlikely that these organisms denitrify 3.

Show full entry

Distribution plant/process configuration

Very common in industrial plants 7.


A number of species have been isolated Thiothrix eikelboomii, T. nivea, T. unzii, T. fructosivorans, T. defluvii. There is also considerable morphological diversity of filaments within the group including the Eikelboom type 021N see images 6.

FISH probes

[G123T] 6 (more specific probes also available)


 In situOther
Aerobic Heterotroph3589
Nitrite Reduction8
Sulphate Reduction9
Fatty Acids34589
Proteins/Amino Acids812

Abundance Information

 10 % percentileMedian90 % percentile
Activated Sludge00.10.3

Predominant InInfluent


[1] - NCBI genome database, NCBI id 1030 -

[2] Lapidus, Nolan, Lucas, Glavina Del Rio, Tice, Cheng, et al. - Genome sequence of the filamentous, gliding Thiothrix nivea neotype strain (JP2(T)). - Stand Genomic Sci 5(3): 398-406. doi:10.4056/sigs.2344929

[3] Nielsen, de Muro, Nielsen - Studies on the in situ physiology of Thiothrix spp. present in activated sludge. - Environ. Microbiol. 2(4): 389-98.

[4] Aruga, Kamagata, Kohno, Hanada, Nakamura, Kanagawa, et al. - Characterization of filamentous Eikelboom type 021N bacteria and description of Thiothrix disciformis sp. nov. and Thiothrix flexilis sp. nov. - Int. J. Syst. Evol. Microbiol. 52(Pt 4): 1309-16. doi:10.1099/00207713-52-4-1309

[5] Howarth, Unz, Seviour, Seviour, Blackall, Pickup, et al. - Phylogenetic relationships of filamentous sulfur bacteria (Thiothrix spp. and Eikelboom type 021N bacteria) isolated from wastewater-treatment plants and description of Thiothrix eikelboomii sp. nov., Thiothrix unzii sp. nov., Thiothrix fructosivorans sp. nov. and Thiothrix defluvii sp. nov. - Int. J. Syst. Bacteriol. 49 Pt 4(): 1817-27. doi:10.1099/00207713-49-4-1817

[6] Kanagawa, Kamagata, Aruga, Kohno, Horn, Wagner, et al. - Phylogenetic analysis of and oligonucleotide probe development for eikelboom type 021N filamentous bacteria isolated from bulking activated sludge. - Appl. Environ. Microbiol. 66(11): 5043-52.

[7] van der Waarde, Krooneman, Geurkink, van der Werf, Eikelboom, Beimfohr, et al. - Molecular monitoring of bulking sludge in industrial wastewater treatment plants. - Water Sci. Technol. 46(1-2): 551-8.

[8] Chernousova, Gridneva, Grabovich, Dubinina, Akimov, Rossetti, et al. - Thiothrix caldifontis sp. nov. and Thiothrix lacustris sp. nov., gammaproteobacteria isolated from sulfide springs. - Int. J. Syst. Evol. Microbiol. 59(Pt 12): 3128-35. doi:10.1099/ijs.0.009456-0

[9] Larkin, J.M., and Shinabarger, D.L. (1983) Characterisation of Thiothrix nivea. Int. J. Syst. Evol. Microbiol. 33(4): 841-846. - Larkin And Shinabarger 1983 -

[10] Nielsen, Mikkelsen, Nielsen - In situ detection of cell surface hydrophobicity of probe-defined bacteria in activated sludge. - Water Sci. Technol. 43(6): 97-103.

[11] Tandoi, V., Caravaglio, N., Di Dio Balsamo, D., Majone, M., and Tomei, M.C. (1994) Isolation and physiological characterisation of Thiothrix sp. Wat. Sci. Technical. 29(7): 261-269. - Tandoi Et Al 1994 -

[12] Wilchek, Oka, Topper - Structure of a soluble super-active insulin is revealed by the nature of the complex between cyanogen-bromide-activated sepharose and amines. - Proc. Natl. Acad. Sci. U.S.A. 72(3): 1055-8.

Hide details

comments powered by Disqus

The online MiDAS field guide is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.


The MiDAS taxonomy is a manual curation of the Silva database and is redistributed for non-commercial use only.


Citing MiDAS: McIlroy S.J., Saunders A.M., Albertsen M., Nierychlo M., McIlroy B., Hansen A.A., Karst S.M., Nielsen J.L., Nielsen P.H. (2015) MiDAS: the field guide to the microbes of activated sludge. Database, Vol. 2015

Contact us at