A role for rare soil bacteria in ecosystem functions

The microbial life in soil is highly diverse with an estimated species number of 104-106 species per gram soil of which the majority is supposed to be rare. In spite of their low abundance they have been found to support important biogeochemical processes, such as denitrification, and contribute to the stability of ecosystem functions under changing environmental conditions. Moreover a study by Hol et al. (2010) has shown that rare soil bacteria can influence plant performance and suggests that they might prime plant defenses against herbivore attack. In my research I address the hypotheses that rare soil microbes provide distinct and vulnerable ecological functions, insure ecosystem processes under environmental changes and disturbances and potentially affect plant performance and herbivore resistance. For this purpose I will first attempt the cultivation of low abundant soil bacteria and their identification by combined high-throughput- and Sanger-sequencing to subsequently test isolates for their ability to degrade specific substrates. On the long term isolated strains will also be investigated for their effect on plant performance and induction of plant resistance to herbivore and pathogen attack. Changes in abundance will be monitored to assess their contribution to ecosystem stability under environmental changes, such as are likely to occur in changed land-use and global warming. This will greatly enhance knowledge about the role of rare bacterial species in ecosystems and the changes in ecosystem processes to be expected in the future.