植物微生物燃料電池對溫室氣體排放及相關功能性基因之影響

Effects of Plant Microbial Fuel Cell on Greenhouse Gas Emissions and Related Functional Genes

洪愷鈞(Kai-Chun Hung)

指導教授 ： 于昌平

國立臺灣大學/工學院/環境工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202003646

摘要

植物微生物燃料電池(Plant microbial fuel cell, PMFC)作為一種新興的綠色能源，具有透過植物將太陽能轉換為電力之能力，藉由系統內部產電菌與甲烷菌、脫硝菌的競爭可能有溫室氣體減量的效果。本研究之目的在於探討植物微生物燃料電池技術應用於濕地對溫室氣體(甲烷和氧化亞氮)的減量以及產電效能，並比較PMFC應用於無鹽害土和鹽害土的差異性。同時對土壤中甲烷、氧化亞氮相關功能性基因進行定量，以了解隨著PMFC系統操作土壤中的功能性菌群變化，以及功能性基因與溫室氣體排放之間的相互關係。
結果顯示無鹽害土PMFC閉路及SMFC (Sediment microbial fuel cell)閉路產生之平均電壓分別為0.21 ± 0.07 V、0.34 ± 0.08 V，PMFC電壓輸出低於SMFC，與文獻中之結果有所出入，可能與研究時期為冬季有關；鹽害土PMFC閉路、SMFC閉路產生之平均電壓分別為0.06 ± 0.04 V、0.02 ± 0.02 V，推測是高鹽度對植物和微生物造成抑制，進而影響電壓輸出。
PMFC系統在產電良好的情況下有甲烷減量的效果，減少氧化亞氮排放的能力則不明確。無鹽害土PMFC甲烷通量由閉路低於開路轉變為閉路高於開路是由於甲烷菌增加，SMFC開路的甲烷菌豐度高於閉路，與SMFC甲烷通量結果相符。鹽害土的甲烷菌豐度隨著時間有上升但幅度不大，鹽害土的甲烷菌豐度遠低於無鹽害土，驗證了鹽害土甲烷通量明顯低於無鹽害土的結果。無鹽害土與鹽害土norB、nosZ、nirK和nirS基因的豐度數量級相當，與兩者氧化亞氮通量差異不大的結果一致。本研究結果尚無法清楚解釋脫硝菌與產電菌的競爭，若要探討脫硝菌與產電菌的關係需要更進一步研究。

關鍵字

植物微生物燃料電池 ； 甲烷 ； 氧化亞氮 ； 功能性基因 ； 數位核酸偵測系統

並列摘要

Plant microbial fuel cell (PMFC), as a emerging green energy source, has the ability to convert solar energy into electricity through plants. It is hypothesized that through competition between electricity-generating bacteria and methanogens and denitrifying bacteria, greenhouse gas emissions could be reduced. The aim of this study is to explore the reduction of greenhouse gases (methane and nitrous oxide) and the power generation efficiency of PMFC technology applied to wetlands, and to compare the difference between PMFC applied to fresh and salt-affected soil. Meanwhile, by quantifying the functional genes related to methane and nitrous oxide in the soil, we can understand the functional consortium shifts as the PMFC systems operate and the correlation between functional genes and greenhouse gas emissions.
The results showed that the average voltages generated by fresh soil close circuit PMFC and close circuit SMFC (Sediment microbial fuel cell) were 0.21 ± 0.07 V and 0.34 ± 0.08 V, respectively. PMFC voltage output was lower than SMFC, which is inconsistent with the literature and may be related to the study period being winter. In salt-affected soil, the average voltages of close circuit PMFC and close circuit SMFC were 0.06 ± 0.04 V and 0.02 ± 0.02 V, respectively. The inhibition of plant and microorganism growth by high salinity may cause the low voltage output.
The PMFC system may have an effect on methane reduction under optimal operation, but the ability to reduce nitrous oxide emissions is unclear. In fresh soil, the PMFC methane flux change from close circuit lower than open circuit to the opposite was due to increased methanogens. In addition, the abundance of methanogens in open circuit SMFC is higher than that in close circuit, which is consistent with the results of SMFC methane flux. The abundance of methanogens in salt-affected soil increased slightly with time, and is much lower than that in fresh soil, which verifies that the methane flux of salt-affected soil is significantly lower than that of fresh soil. The abundances of the norB, nosZ, nirK and nirS genes of fresh soil and salt-affected soil were of the same order of magnitude, which is consistent with the little difference in nitrous oxide flux between the two. From the results of this study, the competition between denitrifying bacteria and electricity-generating bacteria cannot be clearly explained. Further research is required to provide evidence of the relationship between denitrifying bacteria and electricity-generating bacteria.

並列關鍵字

Plant microbial fuel cell ； Methane ； Nitrous oxide ； Functional gene ； Digital PCR

參考文獻

Akiyama, H., Yagi, K., Yan, X. (2005). Direct N2O emissions from rice fields: summary of available data. Glob. Bio. Geo. Chem., Cycles 19 GB 1005.

Allen, R. M., Bennetto, H. P. (1993). Microbial Fuel Cells: Electricity Production from Carbohydrates. Applied Biochemistry and Biotechnology, 39, 27-40.

Arends, J. B., Speeckaert, J., Blondeel, E., De Vrieze, J., Boeckx, P., Verstraete, W., Rabaey, K., Boon, N. (2014). Greenhouse gas emissions from rice microcosms amended with a plant microbial fuel cell. Appl Microbiol Biotechnol, 98(7), 3205-17.

Audet, J., Hoffmann, C. C., Andersen, P. M., Baattrup-Pedersen, A., Johansen, J. R., Larsen, S. E., Kjaergaard, C., Elsgaard, L. (2014). Nitrous oxide fluxes in undisturbed riparian wetlands located in agricultural catchments: Emission, uptake and controlling factors. Soil Biology Biochemistry, 68, 291-299.

Bais, H. P., Weir, T. L., Perry, L. G., Gilroy, S., Vivanco, J. M. (2006). The role of root exudates in rhizosphere interactions with plants and other organisms. Annu Rev Plant Biol, 57, 233-66.