(2/2) While we rested our (speculative) conclusion on the observation of fermentation products after a pulse of simulated root exudation and estimated O2 depletion from CO2 emissions, this new paper now proved it using O2 sensors in combination with reverse Microdialysis. Really interesting read!

Thanks!

Amazing!! 🤩

Thanks to @stefangorka.bsky.social, Alex König, Erich Inselsbacher and others. See also our previous studies on reverse microdialysis to explore microbial dynamics at soil exudation hotspots: doi.org/10.1016/j.so... and doi.org/10.1016/j.so... . Funding: Austrian Science Fund @fwf-at.bsky.social 6/6

Fantastic work by first-author Dr. Julia Wiesenbauer, who also defended her PhD-thesis on Monday. Big congratulations! 😀🥳🎉. 5/6

Our results also emphasize the microbial feedback on root exudation rates. Compounds more readily taken up by microbes (such as OA in our case) can be released at higher rates by passive exudation, while compounds that accumulate at the exudation spot hinder their further (passive) exudation. 4/6

Our results challenge the prevailling assumption that sugars are readily available substrates for soil microbes. The observed microbial preference for organic acids (OA) may indicate a trade-off between rapid biomass growth and ATP yield per unit of substrate uptake. 3/6

Using reverse microdialysis in undisturbed soils we show that, compared to sugars, organic acids were i) removed quicker from the exudation spot, ii) preferentially respired by microbes and iii) led to the production of metabolic byproducts. 2/6