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To exploit the therapeutic potential of secondary metabolites from fungi, Aspergillus niger is chosen as a novel chassis. It is one of the most important microorganisms used in biotechnology, e.g. to produce extracellular (food) enzymes and citric acid. The FDA in the United States has accepted numerous enzymes from A. niger can be ‘generally regarded as safe’ (GRAS) under the condition that non-pathogenic and non-toxigenic strains and current good manufacturing practices be used in production. [1] In our project, Aspergillus niger N593, and 872.11 which are derivatives from N400 are used as our non-pathogenic industrial 'workhorses' to produce secondary metabolites.

As other filamentous fungi, Aspergillus niger should be treated carefully to avoid the formation of spore dust. However, compared with others, it rarely causes allergy or mycopathology. A few medical cases, e.g. lung infections, have been reported, but always in severely immunocompromised patients.[1] A. niger strains produce a series of secondary metabolites, but only ochratoxin A can be regarded as a mycotoxin. The strain we use has already been checked for ochratoxin A production before they are developed as production organisms. Besides, transforming Aspergillus may result in the removal of the auxotrophy marker. N593 and 872.11 stains have the pyrA auxotrophy marker. However, since we work in an ML-1 lab, there is no chance for this organism to escape. It is concluded, with these restrictions, the A. niger strain we introduce to iGEM is a safe organism.

Additionally, instead of focusing on a molecular device as the final goal, we decided to concentrate on engineering an entire chassis as well as generating devices that can be applied in future expansion of the host. We also aim to construct a promoter library that allows for fine-tuning and construction of more complicated network structures in the near future. The devices cover three fundamental processes: cellular trafficking, economy and secretion. It allows for optimization of the production host in demand for food and fuel safety.

References

1.Schuster, E., et al., On the safety of Aspergillus niger–a review. Applied Microbiology and Biotechnology, 2002. 59(4-5): p. 426-435.