Genus nameSmithella
Alternative names
NCBI taxonomy ID182623



16S gene copy number3

 In situOther
Hydrophobic cell surface

MAR–FISH image of propionate-utilizing long rod bacterium present in the anaerobic digester sludge. In situ hybridization was performed with the newly designed specific FITC-labeled SmiLR150 probe after the anaerobic digester sludge was incubated for 3 h at 0.5 mM [14C]propionate. Bar represents 10 microns. - Source:4

Fatty acids

POSNEGVariableNot assessed


Strictly anaerobic, syntrophic, propionate-oxidizing bacteria 5. Found in methanogenic environments 5. Grows syntrophically on propionate only with methanogenic bacteria which utilise and thus remove H2 and formate from the system 5 6 4. Acetate and small amounts of butyrate are formed as end products of propionate oxidation 5. This occurs via the dismutation of propionate to acetate and butyrate, followed by the syntrophic β-oxidation of butyrate to acetate, a pathway so far unique to S. propionica 7. Grows slowly on crotonate in pure culture 5. Cells appear as short and long rods in digester sludge 4.

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FISH probes

SmiSR354 6; SmiLR150 (Smithella sp. long rod) 4


 In situOther
Aerobic Heterotroph465
Nitrite Reduction
Sulphate Reduction625
Fatty Acids465
Proteins/Amino Acids

Abundance Information

 10 % percentileMedian90 % percentile
Activated Sludge000

Predominant InAD - Mesophilic


[1] - NCBI genome database, NCBI id 182623 -

[2] Tan, de Araújo E Silva, Rozycki, Nesbø, Foght - Draft Genome Sequences of Three Smithella spp. Obtained from a Methanogenic Alkane-Degrading Culture and Oil Field Produced Water. - Genome Announc 2(5): . doi:10.1128/genomeA.01085-14

[3] Embree, Nagarajan, Movahedi, Chitsaz, Zengler - Single-cell genome and metatranscriptome sequencing reveal metabolic interactions of an alkane-degrading methanogenic community. - ISME J 8(4): 757-67. doi:10.1038/ismej.2013.187

[4] Ariesyady, Ito, Yoshiguchi, Okabe - Phylogenetic and functional diversity of propionate-oxidizing bacteria in an anaerobic digester sludge. - Appl. Microbiol. Biotechnol. 75(3): 673-83. doi:10.1007/s00253-007-0842-y

[5] Liu, Balkwill, Aldrich, Drake, Boone - Characterization of the anaerobic propionate-degrading syntrophs Smithella propionica gen. nov., sp. nov. and Syntrophobacter wolinii. - Int. J. Syst. Bacteriol. 49 Pt 2(): 545-56. doi:10.1099/00207713-49-2-545

[6] Ariesyady, Ito, Okabe - Functional bacterial and archaeal community structures of major trophic groups in a full-scale anaerobic sludge digester. - Water Res. 41(7): 1554-68. doi:10.1016/j.watres.2006.12.036

[7] de Bok, Stams, Dijkema, Boone - Pathway of propionate oxidation by a syntrophic culture of Smithella propionica and Methanospirillum hungatei. - Appl. Environ. Microbiol. 67(4): 1800-4. doi:10.1128/AEM.67.4.1800-1804.2001

[8] Ito, Yoshiguchi, Ariesyady, Okabe - Identification and quantification of key microbial trophic groups of methanogenic glucose degradation in an anaerobic digester sludge. - Bioresour. Technol. 123(): 599-607. doi:10.1016/j.biortech.2012.07.108

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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

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