Microbial labilization and diversification of pyrogenic dissolved organic matter

Abstract. With the increased occurrence of wildfires around world, interest in chemistry pyrogenic organic matter (pyOM) and its fate environment has increased. Upon leaching from soils by rain events, significant amounts dissolved pyOM (pyDOM) enter aquatic interact with microbial communities that are essential for cycling within different biogeochemical cycles. To evaluate biodegradability pyDOM, aqueous extracts laboratory-produced biochars were incubated soil microbes, molecular changes to composition pyDOM probed using ultrahigh-resolution mass spectrometry (Fourier transform–ion cyclotron resonance–mass spectrometry). Given solar irradiation significantly affects during terrestrial-to-marine export, effects photochemistry also evaluated context biodegradability. Ultrahigh-resolution revealed many (both aromatic aliphatic) compounds biodegraded. New labile produced, 22 %–40 % which peptide-like. These results indicated a portion been labilized into biomass incubations. Fluorescence excitation–emission matrix spectra some fraction these new bio-produced molecules is associated proteinaceous fluorophores. Two-dimensional 1H–1H total correlation nuclear magnetic resonance (NMR) spectroscopy identified peptidoglycan-like backbone microbially produced compounds. consistent previous observations peptidoglycans ocean nitrogen cycles where remnants biodegraded expected be observed. Interestingly, exact nature was found vary drastically among samples indicating consortium used may produce exudates based on initial pyDOM. Another potential explanation vast diversity microbes only consume low molecular-weight compounds, but they reactive oxygen species (ROS), initiate oxidative recombination reactions degrade high molecules. Some (212–308 formulas) estuarine marine (surface abyssal oceanic), 81–192 formulas attributed carboxyl-rich alicyclic (CRAM). indicate biodegradation products have an oceanic can sequestered deep ocean. The observed mediated diversification suggests contributes large complexity natural riverine systems. More broadly, our research shows substrate growth incorporated environmental food webs global carbon