Understanding the Secretory Pathway of A. niger: Harnessing Past Knowledge for Future Advances

Abstract

In the fight to preserve our natural ecosystems, achieve global food security, and mitigate climate change, the establishment of a circular economy is becoming increasingly paramount. In this regard, filamentous fungi present themselves as ideal candidates for the recycling of low-quality waste streams into higher-quality commodities. For over a century, Aspergillus niger has shaped microbial biotechnology, being used for the production of a wide range of industrially relevant compounds. Particularly in the past two decades, the sequencing of its genome, as well as the advent of systems biology and genome editing, has shed more light on the secretory pathway in A. niger. Nevertheless, despite its industrial importance, an inadequate understanding of protein secretion and secretory bottlenecks limits the current potential of A. niger as a biotechnological chassis. This literature review presents our current knowledge of the secretory pathway of A. niger and the engineering approaches that have been utilised to enhance protein secretion yields. In doing so, the present work identifies potential targets for future strain engineering and paves the way for the further development of A. niger as a field-defining cell factory, that can contribute to solving some of today’s greatest challenges.