Interactions between Saprotrophic Bacteria and the white-rot Phanerochaete chrysosporium in presence of wood Extractives

PI : Sophie Mieszkin (UMR 1136 – Interactions Arbres/Micro-organismes – IAM

Co-applicants : Eric Gelhaye (IAM), Philippe Gérardin (LERMAB)

Collaboration: Stéphane Dumarçay (LERMAB), Rodnay Sormani (IAM)

___________________________________________________

Context —

At the scale of forest ecosystems, wood degradation contributes to nutrients recycling and represents an important source of fresh organic matter for lingo-cellulolytic microorganisms. However, during wood degradation, low molecular weight compounds, called extractives, are released. These compounds are potentially toxic and may represent a barrier for microbes. If the contribution of fungal communities in term of carbon and nutrients recycling is well established, the possible role of bacterial communities but also their interactions with fungi were largely underestimated. Recent studies have shown the complexity of these interactions that can be beneficial or not to the fungal or bacterial community or to both communities. Among these studies, one carried out at the IAM laboratory highlighted that the association of the white rot fungi Phanerochaete chrysosporium RP78 with a bacterial community isolated from its mycosphere improved wood degradation. The functional potential of each bacterium forming the bacterial community was characterised, however, their behaviour in presence of wood extractives needs to be defined.

Objective — To evaluate the physiological response and the functional potential of microorganisms and the role of bacterial/fungal interactions (BFI) in presence of wood extractives.

Approach — After characterization of beech, oak and spruce extractives, bacterial and fungal growth kinetics will be performed in presence of wood extractives. Co-cultures will be performed in presence of wood extractives to monitor by surface-plating and qPCR community dynamics in order to decipher whether interactions lead to functional complementation or to competition behavior.

Expected results and impacts — The effect of wood extractives according to their origin on bacterial and fungal growth will be better characterised. Furthermore, the role of BFI on the functional potential of both microorganisms in presence of wood extractives will be highlighted. More generally, this study will improve our knowledge concerning the role of bacteria in the degradation of wood and more specifically during BFI.