Table 1

Comparison of basic features of endosymbiotic and free-living bacteria (ordered by genome size)

Carsonella ruddii

Sulcia muelleri

Buchnera spp.

Mycoplasma genitalium

Blattabacterium spp.

Baumannia cicadellinicola

Wigglesworthia glossinidius


Phylum

γ-Proteobacteria

Bacteroidetes

γ-Proteobacteria

Mollicutes

Bacteroidetes

γ-Proteobacteria

γ-Proteobacteria

Role as symbiont

Obligate, primary, mutualistic

Obligate, primary, mutualistic

Obligate, primary, mutualistic

Pathogen

Obligate, primary, mutualistic

Obligate, primary, mutualistic

Obligate, primary, mutualistic

Host

Psyllids

Sharpshooters

Aphids

Human

Cockroaches

Sharpshooters

Tsetse flies

Genome size (kbp)

160

245

422–686

580

Approximately 650

686

698

GC content (%)

16.5

22.4

20.1–26.2

31.7

Approximately 32

33.2

22.5

Biological function/disease

Nutrition

Nutrition

Nutrition

Genital infections

Nutrition

Nutrition

Nutrition

Location

Intracellular in bacteriocyte

Intracellular in bacteriocyte*

Intracellular in bacteriocyte

Cell associated

Intracellular in bacteriocyte

Intracellular in bacteriocyte*

Intracellular in bacteriocyte

Transmission

Vertical

Vertical

Vertical

Horizontal

Vertical

Vertical

Vertical


Blochmannia spp.

Cadidatus Ishikawaella capsulata

Cadidatus Rosenkranzia clausaccus

Chlamydia trachomatis

Sodalis glossinidius

Escherichia coli K-12

Sorangium cellulosum


Phylum

γ-Proteobacteria

γ-Proteobacteria

γ-Proteobacteria

Chlamydiae

γ-Proteobacteria

γ-Proteobacteria

Myxobacteria

Role as symbiont

Obligate, primary, mutualistic

Obligate, primary, mutualistic

Obligate, primary, mutualistic

Pathogen

Facultative, secondary, commensal

Commensal

Environment

Host

Carpenter ants

Stinkbugs

Stinkbugs

Human

Tsetse flies

Mammalian intestine

Free-living

Genome size (kbp)

705–792

820–830

900–960

1,043

4,170 (972 pseudogenes)

4,639

13,034

GC content (%)

27.4–29.6

38.9 (groEL)§

36–38 (groEL)§

41.3

54

51

71.4

Biological function/disease

Nutrition

Unknown

Unknown

Ocular, lung and genital infections

Influences parasite load (Trypanosoma) of host

Location

Intracellular in bacteriocyte

Extracellular in midgut crypts

Extracellular in midgut crypts

Intracellular

Facultative intracellular

Extracellular

Extracellular

Transmission

Vertical

Vertical

Vertical

Horizontal

Horizontal/vertical

Horizontal


*S. muelleri lives with B. cicadellinicola in the same bacteriocyte. The genome size of S. glossinidius is comparable to that of free-living Enterobacteriaceae, but it is in an early state of degeneration, as exemplified by the massive presence of pseudogenes and a coding capacity of only 51%. §The GC content of the groEL genes is presented for the stinkbug endosymbionts. In the other sequenced endosymbionts the groEL gene has the highest GC content, indicating that the overall GC content of the stinkbug endosymbionts is probably significantly lower.

Feldhaar and Gross Journal of Biology 2009 8:31   doi:10.1186/jbiol129