Aspergillus niger is used in industrial biotechnology as cell factory for the production of chemicals, pharmaceuticals and proteins. During the last years, however, it has become clear that the morphological features of A. niger in fermentation processes are critical to maximum product output. To accomplish a basis for rational genetic engineering of the morphology of A. niger, much more basic knowledge is required to obtain a deeper insight into the molecular networks regulating the morphology of A. niger. Newly established tools such as the availability of the genome sequence of A. niger and of the corresponding Affymetrix DNA microarrays make it now feasible for the first time to study the morphogenetic program of A. niger in a genome-wide approach. In order to get first insights into the regulatory networks involved in the morphogenetic program of A. niger, we made use of two transcriptomic approaches. The first one involved the treatment of young germlings of A. niger with sub-lethal concentrations of antifungal compounds (e.g. caspofungin, inhibitor of β -1,3 glucan synthesis and fenpropimorph, inhibitor of ergosterol synthesis). The rationale behind this approach was based on the observation that A. niger adapts to the inhibitory effect in such a way that it continues to grow by the establishment of new polarity axes and formation of new germ tubes. The second approach made use of the conditional mutant strain Ramosa-1. We found out that this strain represents an excellent and easy controllable model system to study different aspects of fungal polarity, as all critical steps of hyphal morphogenesis (establishment and maintenance of new polarity axes) can be altered in Ramosa-1 by controlling the growth temperature during cultivation. Transcriptomic data from both approaches revealed that different processes seem to participate in the morphogenesis of A. niger, such as cell signalling (TOR, CWI, PIP2), cell wall biosynthesis, cytoskeletal organisation, oxidative stress response and others. The prospective elucidation of the corresponding differentially expressed genes will reveal to what extent they contribute to the morphogenesis of A. niger.
Full conference title:
9th EUROPEAN CONFERENCE ON FUNGAL GENETICS
- ECFG 9th (2008)