Fourier transform ion cyclotron resonance (FT ICR) mass spectrometry data

Understanding dissolved organic matter (DOM) transformation is crucial for
comprehending soil biogeochemical cycling. However, the extent that soil
microbes mediate DOM transformation at the molecular level, and whether
this is regulated by soil management practices such as fertilization
remain largely unknown. We investigated soil DOM transformations under
long-term fertilization using Fourier-transform ion cyclotron resonance
mass spectrometry, high-throughput sequencing, and machine learning.
Fertilization greatly promoted transformation potential of DOM molecules.
Notably, organic fertilization increased the mean transformation number of
DOM molecules by 260% compared to no-fertilization, while chemical
fertilization increased it by 193.33%. Machine learning indicated that
intrinsic DOM molecular characteristics (aromaticity index, oxygen/carbon,
and hydrogen/carbon ratios) could predict transformation potential,
especially for medium- or low-transformation-potential molecules. However,
high-transformation-potential DOM molecules were more influenced by soil
microorganisms that contributed to DOM transformation (e.g.,
Desulfobacterota). Our study provides a parameter to characterize
potential transformation capacity of DOM molecules, the effects of
different fertilization treatments on this potential, and highlights
microbial contributions to molecular transformation processes, identifying
the key microbial groups.