Soil fungi remain active and invest in storage compounds during drought independent of future climate conditions

Abstract

Microbial growth is central to soil carbon cycling. However, how microbial communities grow under climate change is still largely unexplored. In an experiment simulating future climate conditions (increased atmospheric CO2 and temperature) and drought, we traced 2H or 18O applied via water-vapor exchange into fatty acids or DNA, respectively, allowing to measure community- and group-level adjustments in soil microbial physiology (replication, storage product synthesis, and carbon use efficiency, CUE). We show, that while overall community-level growth decreased by half during drought, fungal growth remained stable demonstrating an astonishing resistance of fungal activity against soil moisture changes. In addition, fungal investment into storage triglycerides increased more than five-fold under drought. CUE (the balance between anabolism and catabolism) was unaffected by drought but decreased in future climate conditions. Our results highlight that accounting for different growth strategies can foster our understanding of soil microbial contribution to C cycling and feedback to climate change.

Revisiting soil fungal biomarkers and conversion factors: Interspecific variability in phospholipid fatty acids, ergosterol and rDNA copy numbers

“…Combinations of these data with stable isotope probing and sequencing data provide interesting avenues for future in depth microbial community analyses, and a better resolution for fungal guilds (i.e., saprobes, pathogens and mycorrhizae; Nuccio et al, 2022). A combined analysis of different biomarkers (including also RNA (active), NLFA (storage) and amino sugars (necromass)) would aid for a precise quantification of fungi in soil, in addition to interesting insights into the physiological status of soil fungi under different conditions (Canarini et al, 2023).…”

Beyond Growth: The Significance of Non-Growth Anabolism for Microbial Carbon-Use Efficiency in the Light of Soil Carbon Stabilisation

“…Although we still lack procedures to quantify all types of storage compounds, protocols are readily available for key lipid forms of microbial energy storage (Mason-Jones et al, 2022) including triacylglycerides (Banfield et al, 2017;Gorka et al, 2023;Mason-Jones et al, 2023) and polyhydroxyalkanoates (Mason-Jones et al, 2019). In conjunction with 13 Cor 2 H-labelling, these protocols allow the quantification of small changes in microbial storage over a short time and in combination with substrate-specific and substrate-independent CUE, respectively (Canarini et al, 2023;Mason-Jones et al, 2023). Saccharide storage compounds (i.e.…”