PhD in Biological Sciences and Applied Biotechnologies

Diversity of the fungal enzyme machinery involved in plant biomass breakdown with special reference to secreted heme-peroxidases

The main general research question addressed in this project is “what is the impact of the environment on the functional diversity of fungal communities?” The targeted function is the capacity of these microorganisms to decompose plant biomass, and more specifically lignin, one of the most abundant and highly recalcitrant plant polymers. In recent years, many studies have indeed focused on enzymes involved in lignin degradation, mainly because of their potential biotechnological applications. These enzymes are highly reactive and useful in industrial processes that require the elimination of lignin or other aromatic substrates. These enzymes are used for example for "pulp bleaching" in the paper production, for the elimination of aromatic toxic dyes used in the textile industry. The use of these enzymes is also evaluated for the production of biomass-based second-generation biofuels. However, our knowledge regarding the natural diversity of these enzymes remains fragmentary.

The first objective of the project will be to assess whether different environments, featuring different quantities and “qualities” of aromatic compounds (grassland and forest soils, wood), have selected different types of peroxidases displaying different catalytic activities. In this way it will be possible to understand the relationships between the environment and the diversity of three important gene families encoding fungal peroxidases (class II peroxidases, the dye decolourizing peroxidases and the heme-thiolate peroxidases).

Results from the first objective will allow us to address the ecological/functional contribution of the different fungal species, possessing a specific enzymatic repertoire, in organic matter degradation (second objective).

Thanks to a collaboration with the University of Dresden, the projects also aims at understanding the structure and the effective action of the identified enzymes on different potential substrates.