Engineering Aspergillus niger to obtain high added-value chitosan, a derivative of chitin present in fungal cell walls, from spent mycelial biomass.

The FunChi consortium of three SME and three academic partners from Germany, Netherlands (Leiden University and Dutch DNA), and Spain will overcome two main challenges in industrial scale fungal fermentation as required for the transition from an oil-based to a bio-based economy, namely high viscosity at high cell densities hindering stirring and oxygen transfer, and large amounts of mycelial wastes.

Both problems will be addressed by targeting the cell wall biosynthetic machinery of the model organism and industrial strain of Aspergillus niger. Viscosity will be reduced by aiming at shorter, more branched hyphae leading to micro-pelleted growth. The chitin content of the fungal cell wall will be increased and its incorporation into the complex cell wall will be modified by targeting cross-linking enzymes, so that it can be more easily extracted with better yields and higher quality in terms of polymer size and purity.

We have identified a mutant strain that matches the desired branching growth phenotype without compromising enzyme production (internal data Dutch DNA).  Moreover, another study indicates that the same mutated gene in a related species has an increased cell wall chitin content. Additional high chitin producers are currently being screened and selected from our existing cell wall stress mutant database.

The combined experience of Prof. Peter Punt in fungal fermentation and synthetic biology and Dr. Arthur Ram in fungal cell wall synthesis and morphology and partners provides an excellent knowledge platform in the quest to strain optimization for the FunChi project.

• aspergillus
• bioactive molecules
• cell wall
• chitin
• chitosan
• crh
• gene knock-out

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