Genomic analysis reveals key aspects of prokaryotic symbiosis in the phototrophic consortium “Chlorochromatium aggregatum”
Year: 2013
Type: article
Abstract: BACKGROUND: 'Chlorochromatium aggregatum' is a phototrophic consortium, a symbiosis that may represent the highest degree of mutual interdependence between two unrelated bacteria not associated with a eukaryotic host. 'Chlorochromatium aggregatum' is a motile, barrel-shaped aggregate formed from a single cell of 'Candidatus Symbiobacter mobilis", a polarly flagellated, non-pigmented, heterotrophic bacterium, which is surrounded by approximately 15 epibiont cells of Chlorobium chlorochromatii, a non-motile photolithoautotrophic green sulfur bacterium. RESULTS: We analyzed the complete genome sequences of both organisms to understand the basis for this symbiosis. Chl. chlorochromatii has acquired relatively few symbiosis-specific genes; most acquired genes are predicted to modify the cell wall or function in cell-cell adhesion. In striking contrast, 'Ca. S. mobilis' appears to have undergone massive gene loss, is probably no longer capable of independent growth, and thus may only reproduce when consortia divide. A detailed model for the energetic and metabolic bases of the dependency of 'Ca. S. mobilis' on Chl. chlorochromatii is described. CONCLUSIONS: Genomic analyses suggest that three types of interactions lead to a highly sophisticated relationship between these two organisms. Firstly, extensive metabolic exchange, involving carbon, nitrogen, and sulfur sources as well as vitamins, occurs from the epibiont to the central bacterium. Secondly, 'Ca. S. mobilis' can sense and move towards light and sulfide, resources that only directly benefit the epibiont. Thirdly, electron cycling mechanisms, particularly those mediated by quinones and potentially involving shared protonmotive force, could provide an important basis for energy exchange in this and other symbiotic relationships.
Source: Genome biology
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $5,490
Awards: G1286236842, G1286251239, G1632040200, Microbial Genome Sequencing: Complete Genome Sequences of Green Bacteria, G1863003419, G222768804, G30714459, G3083819904, G3770551199, G419881185, G42916606, G4501827968, LIGHT ENERGY TRANSDUCTION IN GREEN SULFURE BACTERIA, LIGHT ENERGY TRANSDUCTION IN GREEN SULFUR BACTERIA, G498139845, LIGHT ENERGY TRANSDUCTION IN GREEN SULFURE BACTERIA, G5648016710, LINKING BIOENERGETICS AND PHYSICOCHEMICAL ENVIRONMENT WITH THE DISTRIBUTION AND DIVERSITY OF HYDROGENASES IN MICROBIAL COMMUNITIES SUPPORTED BY GEOTH, G650090426, G6652958823, G7205239661, G834277795, G8595358412, G969889393
OpenAlex ID: W2157887530