Tracing the mineralization rates of C, N and S from cysteine and methionine in a grassland soil: A 14C and 35S dual-labelling study. (February 2023)

• Record Type: Journal Article
• Authors: Wang, Deying; Chadwick, David R.; Hill, Paul W.; Ge, Tida; Jones, Davey L.
• Is Part Of: Soil biology and biochemistry. Volume 177(2023)
• Publication Date: 2023-02
• Subjects: Dissolved organic sulphur -- Nutrient availability -- Radioisotope tracers -- 14C tracer -- 35 -- Grassland soil; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2022.108906
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: Sulphur-containing amino acids (i.e. Cysteine (Cys) and methionine (Met)) constitute an important proportion of the soil organic sulphur. However, detailed information regarding the microbial transformation of Cys and Met at a molecular level remain poorly characterized. To trace the fate of carbon (C) and sulphur (S) derived from Cys and Met in an agricultural grassland soil, a 14 C and 35 S dual-isotopic labelling approach was adopted. We also investigated whether their mineralization was affected by manipulating C (added as glucose), nitrogen (N), phosphorus (P) and S (added as NH4 NO3, KH2 PO4 and K2 SO4 ) availability in soil solution. Our results showed that over a 7-day incubation period, 67.2–89.2% of the 14 C derived from Cys and Met was respired as 14 CO2, 2.7–19.5% had been immobilized in the soil microbial biomass; while the recovery of 35 S in soil solution ranged from 6.4 to 9.9%, with the reminder retained in the soil microbial biomass. Overall, our results indicated that soil microbial communities possess a high capacity to utilize Cys and Met. Furthermore, using the 14 C and 35 S dual-labelling technique, we found that C and S derived from Cys and Met were microbially mineralized and immobilized at different rates, indicating that the cycles of these two elements were temporally decoupled at the molecular level. The addition of glucose-C increased 14 CO2 respiration from Cys and Met after 7 d, while in comparison inorganic N, P and S addition had less effect on 14 C and 35 S partitioning. Graphical abstract: Schematic presentation of carbon, nitrogen and sulphur partitioning from two S-containing amino acids in grassland soils after 7-d incubation. a: labelled amino acid uptake into soil microbial biomass; b: subsequent microbial mineralization. ( 35 SFE : ( 35 S in the 0.01 M CaCl2 extract of fumigated soils - 35 S uf ) × 100/0.35/ 35 SO (%)). Image 1 Highlights: 67.2–89.2% of 14 C derived from Cys and Met were respired as 14 CO2 in 168 h. 92.2–93.6% of 35 S derived from Cys and Met retained in soil microbial biomass. N from Cys and Met was firstly released as NH4 +, then rapidly converted to NO3 − . Glucose addition led to significant increase in 14 CO2 respiration from Cys and Met.