在砷及銅污染土壤根圈中的微生物結構及活性

Microbial structure and activities in rhizospheric soils contaminated with arsenic and copper

曾思穎(Shi Wing Chen)

指導教授 ： 許正一

國立臺灣大學/生物資源暨農學院/農業化學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202103191

摘要

本研究在臺灣北部某一砷、銅污染場址中進行實地調查，探討污染土壤中的根圈微生物特性。採集該污染場址中的三種優勢植物，分別為毛葉腎蕨(Nephrolepis hirsutula)，台灣蘆竹(Arundo formosana Hack.)和長葉腎蕨(Nephrolepis biserrata (Sw.) Schott) ，並採集其根圈土壤與附近之非根圈土壤。採集的土壤一部分進行土壤物化性質分析（pH值，有机碳和有效性砷及銅），另一部分鮮土則用於分析微生物的群落結構特性，包括磷脂脂肪酸 (phospholipid fatty acids, PLFA) 、16S rRNA，和β-葡萄糖苷酶，酸性磷酸單酯酶和尿素酶三種酵素活性。實驗結果顯示，該場址土壤中砷和銅的全量最高分別達411 mg/kg及5404 mg/kg 。同時，根圈中的有机碳含量和EDTA萃取之有效性銅均明顯 (P < 0.05) 比非根圈土壤高，而根圈中的NaH2PO4萃取之有效砷的濃度卻降低了87%至93%，因此植物的生長增加了其根圈中的有效性銅的濃度，卻減少了有效性砷的濃度。微生物之PLFA在根圈及非根圈土壤中並沒有明顯的變化。冗餘分析結果顯示微生物PLFA與活性與土壤有效性砷及pH值呈負相關，而與有機碳呈正相關。16S rRNA的分析結果顯示，無論是非根圈或根圈土壤，其主要菌門皆為變形菌門、放線菌門、浮黴菌門、綠彎菌門、酸桿菌門及疣微菌門，佔了土壤中總菌群的90%。在微生物酵素活性方面，台灣蘆竹根圈中的β-葡萄糖苷酶、酸性磷酸單酯酶和尿素酶均顯著 (P < 0.05) 高於非根圈土壤。相較於非根圈土壤，根圈中微生物的PLFA雖然沒有顯著改變，但由於根圈土壤的有機碳增加、有效性砷減少，導致根圈中β-葡萄糖苷酶，酸性磷酸單酯酶和尿素酶的活性增加。

關鍵字

砷 ； 銅 ； 根圈 ； 磷脂脂肪酸 ； 16S rRNA ； 酵素活性 ； 植生穩定

並列摘要

This study conducted a field survey at an arsenic and copper contaminated site in northern Taiwan to characteristize the microbial structures and their enzyme activities in the soils. Three dominant plants at the site, namely Nephrolepis hirsutula，Arundo formosana Hack. and Nephrolepis biserrata (Sw.) Schott, were sampled. Additionally, the rhizosphere and bulk (non-rhizosphere) soils were collected to measure physiochemical properties (pH, organic carbon, and available arsenic and copper) by air-dried samples. Moreover, the fresh soil sample was used to analyze the microbial community structure including phospholipid fatty acids (PLFA) and 16S rRNA and enzymes activities such as β-glucosidase, acid phosphomonoesterase and urease. The experimental results showed that the total concentration of arsenic and copper in the soil of the study site was 411 mg/kg and 5404 mg/kg, respectively. Also, the organic carbon content in the rhizosphere and the bioavailable copper extracted by EDTA were significantly higher (P < 0.05) than in the bulk soil. The concentration of the bioavailable arsenic extracted by NaH2PO4 in the rhizosphere soil was reduced by 87% to 93%. Thus, the plant growth increased the available copper but reduced the available arsenic in the rhizophere. There is no difference significantly of microbial PLFA between rhizosphere and bulk soils. Redundancy analysis results show that the enzymes activity of microbial and PLFA are negatively correlated with soil bioavailable arsenic and pH, and positively correlated with organic carbon. The analysis results of 16S rRNA showed that the main bacteria phyla in bulk and rhizosphere soil are Proteobacteria, Actinomycetes, Planctomycetes, Chloroflexi, Acidobacteria and Verrucomicrobia. These six phyla of bacteria account for about 90% of the total bactera in the soil. In terms of microbial enzyme activities, β-glycosidase, acid phosphomonoesterase, and urease in the rhizosphere soil of A. formosana Hack. were significantly higher than those in the non-rhizosphere soil (P < 0.05). The PLFA of microorganisms in the rhizosphere was comparable to that in the bulk soil, but the organic carbon was higher and the bioavailable arsenic declined in the rhizophere. However, the activities of β-glucosidase, acid phosphomonoesterase and urease were higher in the rhizosphere relative to the bulk soil.

並列關鍵字

arsenic ； copper ； rhizosphere ； phospholipid fatty acid (PLFA) ； 16S rRNA ； enzyme activity ； phytostabilization

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