Volatile and Dissolved Organic Carbon Sources Have Distinct Effects on Microbial Activity, Nitrogen Content, and Bacterial Communities in Soil

• Published in: Microbial ecology Vol. 85; no. 2; pp. 659 - 668
• Main Authors: McBride, Steven G., Osburn, Ernest D., Lucas, Jane M., Simpson, Julia S., Brown, Taylor, Barrett, J. E., Strickland, Michael S.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.02.2023; Springer Nature B.V
• Subjects: Biological activity; Biomedical and Life Sciences; Carbon; Carbon compounds; Carbon sources; Community composition; Composition; Dissolved organic carbon; Ecology; Geoecology/Natural Processes; Glucose; Life Sciences; Low molecular weights; Microbial activity; Microbial Ecology; Microbiology; Microorganisms; Moisture content; Moisture effects; Molecular weight; Nature Conservation; Nitrogen; Organic compounds; Organic soils; Oxalic acid; Prokaryotes; Proteobacteria; Soil; Soil chemistry; Soil Microbiology; Soil microorganisms; Soil moisture; Soil water; Substrates; VOCs; Volatile compounds; Volatile organic compounds; Water content; Water Quality/Water Pollution; α-Pinene; Dissolved organic carbon; Microbial community composition; Amplicon sequencing
• ISSN: 0095-3628; 1432-184X
• DOI: 10.1007/s00248-022-01967-0

Variation in microbial use of soil carbon compounds is a major driver of biogeochemical processes and microbial community composition. Available carbon substrates in soil include both low molecular weight-dissolved organic carbon (LMW-DOC) and volatile organic compounds (VOCs). To compare the effects of LMW-DOC and VOCs on soil chemistry and microbial communities under different moisture regimes, we performed a microcosm experiment with five levels of soil water content (ranging from 25 to 70% water-holding capacity) and five levels of carbon amendment: a no carbon control, two dissolved compounds (glucose and oxalate), and two volatile compounds (methanol and α-pinene). Microbial activity was measured throughout as soil respiration; at the end of the experiment, we measured extractable soil organic carbon and total extractable nitrogen and characterized prokaryotic communities using amplicon sequencing. All C amendments increased microbial activity, and all except oxalate decreased total extractable nitrogen. Likewise, individual phyla responded to specific C amendments—e.g., Proteobacteria increased under addition of glucose, and both VOCs. Further, we observed an interaction between moisture and C amendment, where both VOC treatments had higher microbial activity than LMW-DOC treatments and controls at low moisture. Across moisture and C treatments, we identified that Chloroflexi, Nitrospirae, Proteobacteria, and Verrucomicrobia were strong predictors of microbial activity, while Actinobacteria, Bacteroidetes, and Thaumarcheota strongly predicted soil extractable nitrogen. These results indicate that the type of labile C source available to soil prokaryotes can influence both microbial diversity and ecosystem function and that VOCs may drive microbial functions and composition under low moisture conditions.