Research themes - Molecular Microbiology
- 1. Filamentous fungi and their way of life
Growth and morphology of filamentous fungi is characterized by extreme polarization, resulting in long, elongated cells called hyphae. Hyphal growth is accompanied by polarized secretion of extracellular enzymes at the hyphal tip and by a highly controlled synthesis of the cell wall.
In our research we study polarized cell growth, secretion, cell wall biosynthesis and the developmental program of the biotechnologically important fungus Aspergillus niger. Special emphasis is on fungal morphology as it is very important during large scale cultivation in bioreactors.
We use different omic and cell biological tools to uncover the interconnection of these processes and to understand their roles during the life cycle of A. niger. The knowledge generated, we use to genetically engineer A. niger to further improve it as a host for protein and metabolite production.
- 2. Not knee-deep in garbage! The crucial role microorganisms play in the global carbon-cycle
Without microorganisms dead plant and animal matter would pile up around us. Bacteria and fungi play a vital role in the global carbon cycle by degrading the complex polymers derived from dead plants and animals, and releasing simple monomers which are recycled.
We use molecular biology and transcriptomics technologies which are available for Aspergillus niger to focus on both regulation of the production of polysaccharide degrading enzymes and uptake of monomeric carbon sources. Advances in this field are used to improve industrial processes where A. niger is used as a cell factory for the production of proteins and metabolites.
Phanerochaete chrysosporium is a lignin-degrading fungus which produces many interesting enzymes. Work is being undertaken to establish a genetic transformation system which is necessary for detailed molecular analyses of this organism.
- 3. This seat is taken! How microbes defend themselves or attack unloved neighbors
To understand microbial defense mechanisms, different microbes are studied within the group. Growth strategies (biofilms) as well as defense mechanisms are studied (production of toxins, antibiotics…).
The growing resistance of microbes to antibiotics requires new therapeutics. Extracts from medicinal plants are screened for new anti-microbial peptides that have a high activity against microbial biofilms.
Besides bacterial infections/biofilms, also fungal infections are hard to treat. The development of new antifungal peptides is another focus. A screening system was developed in Aspergillus niger to select for cell wall stress-inducing compounds. Development of synthetic peptides to fight off bacterial and fungal infections is an interesting alternative to infectious control. Studies on fungal development during infection of zebrafish help us understand the infection process and gives us the ability to interfere in these processes.
Pseudomonas strains are well known for their ability to perform biological control. They produce antibiotics, compete for nutrients etc. Mechanisms of biological control are studied extensively. Isolation of endophytic bacteria and the characterization of their lifestyle in plants sheds light on their beneficial influence on plant growth and control of plant crops.
- 4. Small bugs make things better: what microbes can offer to modern biotechnology
Within the research group, we focus on gaining further insight in processes related to improved protein production in fungi. The very specific filamentous growth phenotype and its role in protein production are fascinating aspects of fungal life. To date surprisingly little fundamental research has been carried out towards several already early on identified bottlenecks for fungal protein production; (i) general protein folding and secretion, (ii) specific proteolysis, and (iii) secretion of cofactor dependent proteins (e.g. peroxidases and laccases). In our research we aim to close these gaps in our understanding.
Furthermore, we study the potential of cyanobacteria as new biofuel-generating factories. Cyanobacteria, also known as blue-green algae, obtain their energy through photosynthesis and thus play an important role in the global carbon cycle. Presently, our studies on cyanobacteria are focused on understanding and improving their lipid metabolism - lipids, which in the future could replace a considerable amount of fossil fuels.