Phosphorus (P) is of vital importance for plant production due to the plant metabolic requirements for growth and replication. However, P is taken up by plants and microorganisms only as orthophosphate (Pi). And soil microorganisms known to be more efficient for the assimilation of available P. Therefore, P limits the productivity of plants in many terrestrial ecosystems and is often the first or second element limiting aboveground net primary productivity of forests. Although the use of fertilizers is compensating the deficiency of phosphorus but it gives a worst impact on environment. An important strategy to overcome these problems is the use of natural renewable resources such as soil microorganisms which act as a sink and a source of available phosphorus (P) by mediating key processes in the biogeochemical P cycling. They can regulate the energy transfer processes with low input. In this context the microbial loop, based upon the predation of bacteria by their predator nematodes such as bacteria feeding nematodes, is thought to play a major role in the mineralization of nutrients such as phosphorus in terrestrial ecosystems. However, little is known about the impact of bacterial predation by nematodes on P nutrition of woody plants.

My planned work is in the context of the forth-coming P crisis that will limit biomass production very soon. To face this crisis, I propose to find innovative strategies aiming at better exploiting the soil and microbial P pools. I plan to focus my research activities on using the potential microbial strains which can improve the plant growth in a cheap and renewable way as biofertilizer. My main strategy will rely on a better exploitation of the biological complexity existing between bacteria, their grazers such as bactivorous nematodes. Research aims: Does the nematodes predation of bacterial populations allow it to recycle P effectively after they have immobilized?; (ii) How bacterial predation by bacterivorous nematodes effects bacterial community composition in soil-root under natural environment?; (iii) Does bacterial predation by nematodes improves the growth of pine seedlings?