Sodalis glossinidius

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A Microbial Biorealm page on the genus Sodalis glossinidius


Higher order taxa

Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacteriales; Enterobacteriaceae (1)


Sodalis glossinidius (1)

Description and significance

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.

Symbiotic lifestyle of S. glossinidius (purple) in a haemocyte of the tsetse fly. Image courtesy of Prof. Sue Welburn, University of Edinburgh.

Sodalis glossinidius is a Gram-negative, rod-shaped, filamentous bacteria. It is one of three endosymbionts for the tsetse fly (Glossina spp.), which are all maternally transmitted to progeny. (6,7) This secondary endosymbiont resides inter- and intracellularly in the midgut, fat body and haemolymph of the insect. Though endosymbionts have proven to be difficult to culture, S. glossinidius was isolated and cultured from the haemolymph of Glossinia morsitans morsitans in 1999. S. glossinidius can grow intracellularly in Aedes albopictus or axenically in media containing already enzimatically digested proteins as a nitrogen source. This microaerophilic bacterium grows optimally with 5% oxygen and 95% carbon dioxide at 25 °C. Colony morphology is uniform, with defined edges, and off-white. (7)

The tsetse fly is a vector for Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense, parasitic protozoa that cause African trypanosomiasis (commonly known as African Sleeping Sickness). (9) It is important to study S. glossinidius because it is an endosymbiont of two tsetse fly species which are vectors for Trypanosoma congolense, Trypanosoma brucei gambiense use (6)

important b/c shows insight into the evolution of an endosymbiont becoming dependent on its host

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

Though most organisms of the Family Enterobacteriaceae are able to produce catalase, S. glossinidius is not. This is thought to be why this microbe requires a microaerophilic environment. (7)

Strain M1T did produce a-galactosidase and b-N-acetylglucosaminidase. (7)

S. glossinidius has a relatively inactive biochemical profile compared to other organisms in the family Enterobacteriaceae, likely due to its path away from a free-existence. (7,3)

Interestingly, chitinase production by this micro-organism has been postulated to account for an increase in trypanosome susceptibility in laboratory colonies of G. m. morsitans known to harbour large numbers of S-endosymbionts (Welburn & Maudlin, 1991). In addition to b-N-acetylglucosa (7)

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.


Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Female tsetse fly. Image courtesy of United States Department of Agriculture.

When plated in lab, the beginning of the streak where the inoculum was heavy, produced many large colonies that merged. Toward the end of the streak, where innoculum was thinner, colonies were less abundant smaller colonies. (7) Like other microaerophilic bacteria, S. glossinidius has population-dependent growth where growth rate increases with total respiratory capacity. (7)

about if endosymbionts are gone, larvae cant develop

In the tsetse ¯y (Glossina spp.) P- and S-endosymbionts coexist in the gut lumen, with P-endosymbionts occupying specialized mycetocyte cells in the anterior portion of the insect gut and S-endosymbionts occupying midgut epithelial cells (Huebner & Davey, 1974; Pinnock & Hess, 1974). While the role of each micro-organism has not been clearly de®ned, collectively their presence is known to be essential for egg production and larval development in the insect (Nogge, 1981). Elimination of the bacterial endosymbionts with antibiotics, lysozyme and speci®c antibodies leads to reproductive abnormalities and growth retardation in the aposymbiotic host (Hill & Campbell, 1973; Nogge, 1976, 1978; Pinnock & Hess, 1974; Southwood et al., 1975). (7)

Sodalis glossinidius is one of three endosymbionts of the tsetse fly. [3]


How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Sodalis glossinidius does not cause any known diseases. bacterial uptake due to protein secretory system [5]

Sodalis glossinidius, a maternally transmitted endosymbiont of tsetse flies, maintains two phylogenetically distinct type-III secretion systems encoded by chromosomal symbiosis regions designated SSR-1 and SSR-2. Although both symbiosis regions are closely related to extant pathogenicity islands with similar gene inventories, SSR-2 has undergone novel degenerative adaptations in the transition to mutualism. Notably, SSR-2 lacks homologs of genes found in SSR-1 (3) ...mutualism so wouldn't be able to survive in another host to infect.

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

S. glossinidius has lost much of its biochemical profile.(7) Genetic material for compounds and enzymes have drifted into pseudogene status due its specialized environment, the tsetse fly.(3) There are no known biotechnological benefits to society.

Current Research

Enter summaries of the most recent research here--at least three required

Some of the recent research on Sodalis glossinidius:

"The endosymbionts of tsetse flies: manipulating host–parasite interactions" [6]


1. "Sodalis glossinidius". NCBI Taxonomy Browser. 26 August 2007. [1]

2. Akman, L., Rio, R., Beard, C., and Aksoy, S. “Genome Size Determination and Coding Capacity of Sodalis glossinidius, an Enteric Symbiont of Tsetse Flies, as Revealed by Hybridization to Escherichia coli Gene Arrays.” Journal of Bacteriology. 2001. Volume 183.15 p. 4517-4525.[2]

3. Dale, C., Jones, T., and Pontes, M. "Degenerative Evolution and Functional Diversification of Type-III Secretion Systems in the Insect Endosymbiont Sodalis glossinidius." Molecular Biology and Evolution. 2005. Volume 22.3 p. 758-766. [3]

4. Darby, A., Lagnel, J., Matthew, C., Bourtzis, K., Maudlin, I., and Welburn, S. "Extrachromosomal DNA of the Symbiont Sodalis glossinidius." Journal of Bacteriology. 2005. Volume 187.14 p. 5003-5007. [4]

5. Collazo, C., and Galán, J. "The invasion-associated type-III protein secretion system in Salmonella – a review." Gene. 1997. Volume 192.1 p. 51-59. [5]

6. Dale, C., and Welburn, S. "The endosymbionts of tsetse flies: manipulating host–parasite interactions." International Journal for Parasitology. 2001. Volume 31.5-6 p. 627-630. [6]

7. Dale, C., and Maudlin, I. "Sodalis gen. nov. and Sodalis glossinidius sp. nov., a microaerophilic secondary endosymbiont of the tsetse fly Glossina morsitans morsitans." International Journal of Systematic Bacteriology. 1999. Volume 49 p. 267–275. [7]

8. Aksoy, S., and Rio, R. "Interactions among multiple genomes: Tsetse, its symbionts and trypanosomes." Insect Biochemistry and Molecular Biology. 2005. Volume 35.7 p. 691-698. [8]

9. Maudlin, I. "African trypanosomiasis." Annals of Tropical Medicine & Parasitology. 2006. Volume 11.8 p. 679–701. [9]

Edited by Janet Melnyk, student of Rachel Larsen