奈米和微米級TiO2, SiO2和Al2O3對本土水蚤、大腸桿菌、小白菜和空心菜的毒性及土壤菌相的影響

Abstract

本研究探討三種奈米級及微米級氧化材料TiO2, SiO2和Al2O3對本土水蚤 (Daphnia pulex) 、大腸桿菌 (E. coli) 和葉菜類小白菜 (Chinese cabbage) 和空心菜 (Water spinach) 的毒性，並結合核酸萃取、聚合酶鏈鎖反應 (Polymerase chain reaction, PCR) 及變性凝膠梯度電泳 (Denaturing gradient gel electrophoresis, DGGE) 等分子生物技術來探討三種奈米級材料對土壤中細菌族群結構之影響。結果發現TiO2, SiO2和Al2O3三種材料中，以Al2O3對水蚤的毒性最大，TiO2次之。奈米級和微米級粒子懸浮液對大腸桿菌的生長影響試驗中，Al2O3的毒性最大，TiO2次之，SiO2最小，奈米材料抑制程度大於微米材料。抑制情況主要發生於加入懸浮液處理的初期，時間經過越久，生長曲線有趨近於對照組之跡象。藉由電子顯微鏡的觀察，發現奈米粒子會聚集於大腸桿菌細胞周圍，但仍無法斷定是否侵入細胞體。奈米TiO2, SiO2和Al2O3懸浮液葉面施灑試驗中，發現對小白菜葉綠體合成有明顯抑制，並且產生植物逆境指標脯胺酸 (Proline) ，而在以上兩項指標中，空心菜對處理都顯示出比小白菜更高的耐受度。氧化逆境指標丙二醛 (Malondialdehyde, MDA) 的檢測結果在所有葉面施灑處理樣品中都無顯著差異。以奈米懸浮液對採集自桃園區農業改良場之坡堵系土壤 (簡稱Pu土壤) 及花蓮區農業改良場之五里林系土壤 (簡稱Wl土壤) 做菌相變化分析的試驗中，於土中添加濃度為10000和1000 mg L-1的奈米粒子懸並觀察菌相變化的試驗發現菌相變化大致在處理初期受到較嚴重影響，然而距離處理時間越長，菌相開始恢復並趨於平衡，顯示奈米懸浮液對土壤菌相的影響並不具持久性。

The effect of three nano- and micro-size materials including TiO2, SiO2 and Al2O3 on water flea, Escherichia coli, chinese cabbage, water spinach and the effect on soil bacterial community structure were studied here. Among the three materials, Al2O3 showed the highest toxicity toward water fleas . The rank of the toxicity of the three materials was Al2O3>TiO2>SiO2 for E.coli growth, nano particles showed higher toxicity than micro particles. The inhibition was obvious right after the amendment.,but would recover fastly with time. Nanoparticle gather around the surface of cells with the inspection of TEM, but whether or not the particle had enter into the cell could not be determined. In the test spraying Nano-TiO2, SiO2 and Al2O3 suspension onto the plant leaves, significant inhibition of chlorophyll on chinese cabbage was discovered, but only slight inhibition was observed on water spinach. Proline was produced more in chinese cabbage than that in water spinach after the treatment. Both no significant difference were shown on the production of MDA. It was concluded that water spinach showed more tolerance than chinese cabbage from the above indexes. Soil samples which collected from Taoyuan District Agricultural Research and Extension Center (Pu) and Hualien District Agricultural Research and Extension Center (Wl) were used in the nanoparticle (with concentrations 10000 and 1000 mg L-1) suspension incubation test. The bacterial community structure in the first 24h in most of the soil samples are quit different, but the effect wouldn’t continue for a long time.