TY - JOUR

T1 - Utilisation and transformation of organic and inorganic nitrogen by soil microorganisms and its regulation by excessive carbon and nitrogen availability

AU - Pan, Wankun

AU - Zhou, Jingjie

AU - Tang, Sheng

AU - Wu, Lianghuan

AU - Ma, Qingxu

AU - Marsden, Karina A.

AU - Chadwick, David D. R.

AU - Jones, Davey L.

PY - 2023/5

Y1 - 2023/5

N2 - The process of nitrogen (N) transformation after microbial utilisation of organic and inorganic N is unclear. 15N-glycine (Gly), 15NH4+ and 15NO3− were used to investigate the uptake, release and reutilisation of N by microorganisms over 9 days. In addition, high amounts of unlabelled carbon (C) or N were added to explore how C or N availability affects the cycling of inorganic and organic N by microorganisms. Within 15 min, 67% of the added 15N-Gly was taken up by soil microorganisms; within 1 h, 8% was released as NH4+. The released 15NH4+ was reutilised by the microorganisms within hours. Microorganisms took up 50% of the added 15NH4+ (15 min) and released 13% of the taken up NH4+ (1 h). Microorganisms prefer to take up Gly rather than NH4+ because they can directly acquire C from Gly for maintaining its growth and synthesising more complex compounds. NO3− was taken up by microorganisms within minutes but not released into the soil. NO3− was likely stored in the cytoplasm, to be used as an N source to face future N-deficient environments. When high concentrations of C or N were added, the assimilation of Gly and NH4+ increased, whereas N mineralisation and nitrification rates decreased, and the uptake of NO3− remained stable. Overall, Gly and NH4+ were taken up, released and re-taken up by microorganisms and were preferentially utilised under excess C or N sources, while NO3− was stored in the microbiome. These findings provide new insights into N uptake by microorganisms in short-term.

AB - The process of nitrogen (N) transformation after microbial utilisation of organic and inorganic N is unclear. 15N-glycine (Gly), 15NH4+ and 15NO3− were used to investigate the uptake, release and reutilisation of N by microorganisms over 9 days. In addition, high amounts of unlabelled carbon (C) or N were added to explore how C or N availability affects the cycling of inorganic and organic N by microorganisms. Within 15 min, 67% of the added 15N-Gly was taken up by soil microorganisms; within 1 h, 8% was released as NH4+. The released 15NH4+ was reutilised by the microorganisms within hours. Microorganisms took up 50% of the added 15NH4+ (15 min) and released 13% of the taken up NH4+ (1 h). Microorganisms prefer to take up Gly rather than NH4+ because they can directly acquire C from Gly for maintaining its growth and synthesising more complex compounds. NO3− was taken up by microorganisms within minutes but not released into the soil. NO3− was likely stored in the cytoplasm, to be used as an N source to face future N-deficient environments. When high concentrations of C or N were added, the assimilation of Gly and NH4+ increased, whereas N mineralisation and nitrification rates decreased, and the uptake of NO3− remained stable. Overall, Gly and NH4+ were taken up, released and re-taken up by microorganisms and were preferentially utilised under excess C or N sources, while NO3− was stored in the microbiome. These findings provide new insights into N uptake by microorganisms in short-term.

KW - Organic nitrogen uptake

KW - Inorganic nitrogen uptake

KW - C and N bioavailability

KW - Isotopic labelling

U2 - 10.1007/s00374-023-01712-w

DO - 10.1007/s00374-023-01712-w

M3 - Article

VL - 59

SP - 379

EP - 389

JO - Biology and Fertility of Soils

JF - Biology and Fertility of Soils

SN - 0178-2762

IS - 4

ER -