Earthworms and Sphingobacterium sp. are known for their strong organic compound decomposition ability and wide distribution in soil. However, interactions of soil organic matter decomposition with soil properties and whether microbial species such as Sphingobacterium sp. could assist earthworms in carbon and nitrogen transformation in soil remain poorly understood. Earthworms (Eisenia fetida, Amynthas gracilis) and Sphingobacterium sp. were introduced in non-contaminated and cadmium-contaminated soils under controlled laboratory conditions for 20 days. We examined their individual or combined effects on carbon and nitrogen forms and related enzyme activities to assess their influence on soil C and N cycling. Individual Sphingobacterium sp. inoculation led to significantly decreased organic carbon (SOC) contents, reducing it by 16.5% in non-contaminated soil and by 3.77%, in Cd-contaminated soil. It resulted in an increased microbial biomass carbon (MBC) contents, reaching 1685 ± 292 mg·kg−1 in non-contaminated soil. Individual introductions of E. fetida and A. gracilis caused a decline in SOC content in non-contaminated soil, but increased significantly dissolved organic carbon (DOC) and alkali-hydrolysable nitrogen (AN) contents by 75.8%, 53.6% and 32.9%, 20.9%, respectively. In contrast, in Cd-contaminated soil, only the significant combined effects of earthworms and Sphingobacterium sp. were linked to significant increase in SOC contents, raising by 7.22% and 9.64% in E. fetida + Sphingobacterium sp. and A. gracilis + Sphingobacterium sp. treatments, respectively. In non-contaminate soil, the combined effects of earthworm and Sphingobacterium sp. further increased DOC and AN content by 212%, 134% and 31.3%, 25.4% in the treatments of E. fetida + Sphingobacterium sp. and A. gracilis + Sphingobacterium sp., respectively; the highest ratios of DOC to SOC and AN to total Nitrogen (TN) were found in the earthworm + Sphingobacterium sp. treatments as well. In non-contaminated soil, Sphingobacterium sp. and earthworms mainly influenced β-glucosidase (BG), urease (URE), N-acetyl-β-d-glucosaminidase (NAG) activities and fluorescein diacetate hydrolysis (FDA) hydrolysis, while in Cd-contaminated soil, they mainly influenced invertase (INV), NAG, URE, and protease (PRO) activities. Principal component analysis indicated that in non-contaminated soil, the earthworm activities dominated the mineralization processes of soil carbon and nitrogen, and Sphingobacterium sp. can intensify this process when it was inoculated in soil along with earthworms. Furthermore, both earthworm species increased C and N levels by elevated INV and PRO activities in combined inoculation. However, in contaminated soil, the impact of earthworm inoculation on soil C stabilization showed a species dependent pattern. E. fetida reduced C mineralization by decreasing URE activities, while A. gracilis enhanced C stabilization by increasing INV activities and decreasing PRO activities. In conclusion, earthworms played a key role in enhancing C and N mineralization in non-contaminated soil and promoting C stabilization in contaminated soil. Both earthworm species followed similar strategies in the former process but adopted different strategies in the latter. When introduced individually, Sphingobacterium sp. was able to promote mineralization in both soils, primarily assisting earthworms in improving carbon and nitrogen mineralization in non-contaminated soil but hindering these processes in Cd-contaminated soil. These findings provide insights into the combined effects of earthworms and microorganisms on carbon and nitrogen cycling.
Authors
Li Jia, Qing Liu, Siyi Chen, Kexue Liu, Yiqing Chen, Mikael Motelica-Heino, Hesen Zhong, Menghao Zhang, Cevin Tibihenda, Patrick Lavelle, Jun Dai, Chi Zhang
- Bibliographic Reference
- Li Jia, Qing Liu, Siyi Chen, Kexue Liu, Yiqing Chen, et al.. Individual and combined effects of earthworms and Sphingobacterium sp. on soil organic C, N forms and enzyme activities in non-contaminated and Cd-contaminated soil. European Journal of Soil Biology, 2024, 120, pp.103576. ⟨10.1016/j.ejsobi.2023.103576⟩. ⟨insu-04326301⟩
- DOI
- https://doi.org/10.1016/j.ejsobi.2023.103576
- HAL Collection
- ['IRD - Institut de recherche pour le développement', 'Observatoire de Paris', "INSU - Institut National des Sciences de l'Univers", 'Bureau de Recherches Géologiques et Minières', 'CNRS - Centre national de la recherche scientifique', "Université d'Orléans", "institut des sciences de la terre d'orléans", "Observatoire des Sciences de l'Univers en région Centre", 'Université Paris-Est Créteil Val-de-Marne', "Institut d'écologie et des sciences de l'environnement de Paris", 'Sorbonne Université', 'Université Paris sciences et lettres', 'Sorbonne Université 01/01/2018', 'Faculté des Sciences de Sorbonne Université', 'Institut National de Recherche en Agriculture, Alimentation et Environnement', 'Observatoire de Paris - PSL', 'Sorbonne Université - Texte Intégral', 'Alliance Sorbonne Université', 'Institut écologie et environnement du CNRS']
- HAL Identifier
- 4329616
- Institution
- ['South China Agricultural University', 'Bureau de Recherches Géologiques et Minières (BRGM)', "Institut national des sciences de l'Univers", 'Observatoire de Paris', "Université d'Orléans", 'Institut de Recherche pour le Développement', 'Université Paris-Est Créteil Val-de-Marne - Paris 12', 'Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement']
- Laboratory
- ["Institut des Sciences de la Terre d'Orléans - UMR7327", "Institut d'écologie et des sciences de l'environnement de Paris"]
- Published in
- France
Table of Contents
- Individual and combined effects of earthworms and Sphingobacterium sp. on soil organic C N forms and enzyme activities in non-contaminated and Cd-contaminated soil 1
- Different combined effects of earthworm and Sphingobacterium 40
- Different combined effects of earthworm and 43
- Sphingobacterium sp. on soil C N forms and enzyme 43
- 1. Introduction 47
- 2. Materials and methods 50
- 2.1 Soil earthworm and strain 50
- 2.2 Experimental designs 51
- 2.3 Soil properties enzyme activity content and DTPA of Cadmium 52
- 2.4 Statistics analysis 52
- 3. Results 53
- 3.1 Earthworm survival rate and biomass 53
- 3.2 The content of carbon and nitrogen fractions 53
- 3.3 The ratio characteristics of carbon and nitrogen fractions 55
- 3.4 Response of soil enzymes activity to inoculated earthworm and 55
- Sphingobacterium 55
- 3.5 Relationships among carbon nitrogen and related enzymes activity 56
- 4. Discussion 57
- 4.1 Earthworm growth and survival 57
- 4.2 Effects of earthworms and Sphingobacterium on soil carbon and 58
- 4.3 Effect of earthworms and Sphingobacterium on soil enzyme 60
- Effect of earthworms and Sphingobacterium on the balance of soil 62
- 5. Conclusion 63
- Acknowledgements 64
- Reference 65
- Individual and combined effects of earthworms and 77
- Sphingobacterium sp. on soil organic C N forms and enzyme activities 77
- 1. Introduction 80
- 2. Materials and methods 83
- 2.1 Soil earthworms and strain 83
- 2.2 Experimental design 83
- 2.3 Soil properties carbon and nitrogen forms enzyme activities 84
- 2.4 Total and DTPA extractable Cadmium content 84
- 2.5 Statistics analysis 84
- 3. Results 85
- 3.1 The contents of carbon and nitrogen forms 85
- 3.2 The ratios of carbon and nitrogen forms 85
- 3.3 Response of soil enzyme activity to inoculated earthworms and Sphingobacterium 86
- 3.4 Earthworm survival rate and mean biomass loss 86
- 3.5 General effects of the treatments on soil C N and related enzyme activity 86
- 4. Discussion 87
- 4.1 The effects of Sphingobacterium on C mineralization 87
- 4.2 Earthworm survival growth and species-specific effects on C and N 87
- 4.3 The combined effects of earthworm and Sphingobacterium on the balance 89
- 5. Conclusion 91
- Acknowledgements 91
- Reference 91
- Table list 103
- Figure captions 106
- Figure captions 111
- Table list 117
- Supplementary Material 121
- Supplementary Material-EJSB.docx 121
- Supplementary Material 122
- EJSB-Supplementary Material.docx 122
