Rhizopus microsporus
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| Tiegh. |
Rhizopus microsporus is a species of mushroom . Some strains of this Zygomycota ,which mainly lives in the soil,canenter intoa symbiosis with bacteria of the genus Burkholderia that grow intracellularly.
The mold is only capable of vegetative reproduction in the presence of the bacteria, during which the bacteria are secreted into the spores. The bacteria produce the toxin rhizoxin, which causes the symptoms of rice seedling rot. This inhibits the growth of the rice roots, which impairs the development of the plants and often leads to death. The nutrients released from the dead plants are absorbed by the two symbiotic partners and used for their own growth. Rhizoxin inhibits cell division in the seedlings by binding to the β- tubulin units and thereby preventing their polymerisation . Therefore a new cytoskeleton cannot be built; Cell division is prevented. Since the toxin acts in most eukaryotic cells, research is being conducted into the use of this substance in the treatment of cancer .
The fungus itself is resistant to the toxin because its β-tubulin has a mutation at the 100th amino acid position, so that rhizoxin can no longer bind here. This mutation was probably a basis for the development of the symbiosis between Rhizopus and Burkholderia.
Other examples of a symbiosis between fungi and bacteria are blue - green algae , in which cyanobacteria live extracellularly. Cyanobacteria of the genus Nostoc live in an endosymbiosis with the fungus Geosiphon pyriformis .
The variety Rhizopus microsporus var. Oligosporus is used to produce tempeh .
Individual evidence
- ↑ Partida-Martinez LP et al. (2007): Endosymbiont-Dependent Host Reproduction Maintains Bacterial-Fungal Mutualism. Current Biology, Vol. 17, p. 773-777
- ↑ Partida-Martinez LP & Hertweck C (2005): Pathogenic fungus harbors endosymbiotic bacteria for toxin production. Nature, vol. 437, p. 884-888
- ↑ Schmitt I, Partida-Martinez LP, Winkler R, Voigt K, Einax E, Dölz F, Telle S, Wöstemeyer J, Hertweck C (2008): Evolution of host resistance in a toxin-producing bacterial-fungal alliance. ISME J. 2, 632-641