9n98-2026-01-15_09_37_56-lepori-et-al-2025-who-is-who-in-necromass-formation-and-stabilization-in-soil-the-role-of-fungi-and-bacteria-as-complementary-playe.pdf
9n98-2026-01-15_09_37_56-lepori-et-al-2025-who-is-who-in-necromass-formation-and-stabilization-in-soil-the-role-of-fungi-and-bacteria-as-complementary-playe.pdf
Who is who in necromass formation and stabilization in soil? The role of fungi and bacteria as complementary players of biogeochemical functioning
Abstract
Abstract
Multiple global change drivers have caused a large carbon debt in our soils. To remedy this debt, understanding the role of microorganisms in soil carbon cycling is crucial to tackle the carbon soil loss. Microbial carbon use efficiency is a parameter that captures the formation of microbially-derived soil organic matter. While it is known that biotic and abiotic drivers influence carbon use efficiency, it remains unclear whether bacteria, fungi and their interactions influence the formation of microbially-derived soil organic carbon and its persistence in soils. Here, we combined the inoculation of distinct communities grown at different moisture levels to manipulate the formation of microbial necromass in a model soil. In a follow-up experiment, we then evaluated the persistence of this previously formed microbially-derived carbon to decomposition. While we show that necromass formation reflects the microbial community composition, the soil organic carbon formed within the most complex community of bacteria and fungi seems to be more resistant to decomposition compared to the soil organic carbon formed within the simpler communities bacteria and fungi simple community, bacteria only and fungi only communities. Moreover, fungal necromass proved to be more thermally-stable than bacterial necromass, if this necromass is formed with both bacteria and fungi present. Our findings reveal that although abiotic factors can influence microbial physiology, the biological origin of microbially-derived carbon and the co-occurrence of fungal and bacterial growth were the stronger drivers explaining soil organic matter persistence in these soils, suggesting the importance of microbial succession in soil organic carbon stabilization.