Changes in bacterial community structure and humic acid composition in response to enhanced extracellular electron transfer process in coastal sediment
Humic acids are one of the main organic matters in sediments and contribute importantly to the marine biogeochemical cycles. Extracellular electron transfer is a ubiquitous natural process and has potentials to change the macrostructure of humic acids which can act as an electron shuttle. By setting up marine sediment microbial fuel cells, the present study revealed that enhanced extracellular electron transfer process could increase the content of C and H, but decrease the O content in humic acids, which could result in an increased aromaticity and decreased polarity of humic acids, whereas no significant changes occurred to the humification degree of the humic acids. Specific bacterial groups as potential exoelectrogens including Proteobacteria (especially Pseudomonas strains) and Firmicutes were enriched under enhanced extracellular electron transfer process, indicating that they were active to exchange electrons and might play important roles during the changes of humic acids, while the relative abundance of Verrucomicrobia and Bacteroidetes was reduced during these processes. The results of the present research shed lights on the relation between exoelectrogens and the transformation of humic acids in coastal sediment, while the microbial process and mechanisms behind it require further study.
KeywordsHumic acids Extracellular electron transfer Exoelectrogens Bacterial community structure Sediment microbial fuel cell
This work was supported by the National Key Research and Development Program of China (2016YFA0601402), the Open Task of Qingdao National Laboratory for Marine Science and Technology (Grant no. QNLM2016ORP0311), 2017 President’s International Fellowship Initiative of the Chinese Academy of Sciences (CAS PIFI 2017VCA0019) supported the contribution of Robina Farooq, QIBEBT and Dalian National Laboratory For Clean Energy (DNL), CAS (Grant: QIBEBT ZZBS 201805).
Zejie Wang and Jiulong Zhao carried out the experiment and wrote the paper. Long Wang contributed to bioinformatics and statistical analysis. Lili Tang, Rui Ren, and WuxinYou helped to carry out the DNA extraction, elemental analysis, and FT-IR analysis. Robina Farooq and Yongyu Zhang contributed to the experimental design and data analysis. All authors participated in the interpretation of the results, critically revising manuscripts, and approving the final manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Nepomnyashchaya YN, Slobodkina GB, Baslerov RV, Chernyh NA, Bonchosmolovskaya EA, Netrusov AI, Slobodkin AI (2012) Moorella humiferrea sp. nov., a thermophilic, anaerobic bacterium capable of growth via electron shuttling between humic acid and Fe(III). Int J Syst Evol Microbiol 62:613–617CrossRefGoogle Scholar
- Piccolo A, Spaccini R, Drosos M, Vinci G, Cozzolino V (2018) Chapter 4—the molecular composition of humus carbon: recalcitrance and reactivity in soils. In: The future of soil carbon. Wiley, pp 87–124Google Scholar
- Schlesinger WH (1997) Biogeochemistry: an analysis of global change, 2nd edn. Houston, TexasGoogle Scholar
- Stevenson FJ (1994) Humus chemistry. Genesis, composition, reactions, 2nd edn. Wiley, New YorkGoogle Scholar
- Yang Y, Xu M (2019) Bioelectroremediation of Sediments. In: Wang AJ, Liang B, Li ZL, Cheng HY (eds) Bioelectrochemistry stimulated environmental remediation. Springer, SingaporeGoogle Scholar
- Zeng YH, Jiao NZ, Cai HY, Chen XH, Wei CL (2004) Phylogenetic diversity of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit genes of bacterioplankton in the East China Sea. Acta Oceanol Sin 23:673–685Google Scholar