耐銦細菌對水稻幼苗中銦轉運之影響

Effect of the indium-tolerant bacteria on the translocation of indium in rice seedlings

林建宏(Jian-Hong Lin)

指導教授 ： 林乃君

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/NTU202101384

摘要

高科技產業日漸發展，為人類生活帶來更多便利，然而伴隨而來的可能會有新興汙染物的汙染，如鎵和銦。先前研究調查發現新竹科學園區之排放廢水含有 0.05~10.0 μg L-1 的銦。前人研究注重在銦對動物與植物的影響，然而對微生物之影響研究反而不多，故我們想從銦是否對微生物有毒害，及土壤中是否具有耐銦之微生物開始了解，繼而利用水稻幼苗建立之接近無菌栽培系統來探討這些微生物對植體中銦轉運之影響。利用增殖培養之方式，在平鎮與三坑子土系中共分離到 59 支能夠抗鎵、銦或鉈能力之菌株，且其中多株菌株具有能夠同時耐受兩種以上重金屬之能力；再透過培養基測試各菌株之促進植物生長 (plant growth-promoting, PGP) 能力，發現有 23 支菌具螯合鐵之能力， 10 支菌具有溶磷能力，而 36 支菌具有降解尿素之能力，但僅有 5 支菌可產生植物荷爾蒙中的吲哚乙酸 (indole acetic acid, IAA)。從銦轉運效率上升的水稻植株根部分離根圈菌與內生菌，一共分離出 9 支根圈菌和 2 支內生菌，其中 In200/SE R-2 與 In200/SE R-6 具有產生鐵載體之螯合鐵能力；In200/SE R-3、In200/SE R-4 與 In50/SE R-2 具有溶磷之能力；In200/SE R-2、In200/SE R-6、In50/SE R-1 與 In50/SE R-2 具有產生尿素酶之能力；In200/SE R-5、In200/SE R-6、In50/SE E-1、 In50/SE E-2 與 In50/SE R-1 對 200 mg/L 之銦有良好耐受性。在開蓋近無菌土壤系統中，添加Bacillus sp. E1 於土壤中且在 50 mg/L 之銦處理下，可以使水稻之地上部銦濃度累積量增加，從轉運係數 (translocation factor, TF) 值來看，In50/E1 組之 TF 值為 0.072 較 In50 組之 TF 值 0.037 來的高，表示 E1 具有增加銦在水稻中轉運之能力。除此之外，Bacillus sp. E1 菌體能夠吸附銦，量可達到約 8.37 mg/g cells。然而，E1 對水稻植體中銦之轉運增加的實際機制為何以及吸附銦的機制為何，仍需等待進一步之研究探討。本研究發現土壤中具有能夠幫助植物將銦轉運到地上部，且能吸附銦的細菌，未來應可將此菌株用於發展提升植生復育效率上，使植物吸收更多重金屬並轉運到地上部；此外，也可用在銦之回收利用，減少為了銦而過度開採造成環境之破壞。

關鍵字

銦 ； 水稻 ； 耐銦細菌 ； 轉運因子

並列摘要

The development of high-tech industry brought more convenience to human life, but the pollution of rare earth elements such as gallium and indium might be accompanied. Previous research found that the wastewater from Hsinchu Science Park contained 0.05-10.0 μg L-1 indium. Compared to abundant studies on the effects of indium on animals and plants, fewer reports on the effects of indium on microorganisms were published. Therefore, I would like to know whether indium is toxic to microorganisms, whether there are indium-tolerant microorganisms in soil, and whether microorganisms can affect translocation of indium in planta. By means of enrichment culture, 59 strains were found to be able to resist gallium, indium or thallium, and many strains were able to withstand more than two kinds of heavy metals simultaneously. Through the PGP ability tests, 23 strains could produce siderophores, while 10 bacteria had the ability to dissolve phosphate. Thirty-six bacteria had the ability to produce urease, but only 5 bacteria could produce IAA. In the experiment of isolating rhizospheric and endophytic bacteria, 11 rhizobacteria were isolated, including 9 rhizospheric and 2 endophytic bacteria, of which In200/SE R-2 and In200/SE R-6 had ability to produce siderophore. In200/SE R-3, In200/SE R-4 and In50/SE R-2 had phosphate solubilizing ability. In200/SE R-2, In200/SE R-6, In50/SE R- 1 and In50/SE R-2. The results showed that the enzyme production capacity was good, and In200/SE R-5, In200/SE R-6, In50/SE E-1, In50/SE E-2 and In50 /SE R-1 were well tolerated to 200 mg/L indium. In open, nearly aseptic soil system, addition of Bacillus sp. E1 to soil containing 50 mg/L indium could increase the accumulation of indium in the upper part of rice seedlings. The TF value of the In50/E1 group was 0.072, higher than that of the In50 group, indicating that E1 has the ability to promote indium translocation in rice. In addition, indium could be adsorbed on E1, and the amount adsorbed was about 8.37 mg/g cells. However, the mechanism of E1 increasing indium transport and how it adsorbs indium remains to be investigated. In the future, E1 can be used to enhance efficiency of phytoremediation as well as materials to recover indium from e-wastes, thus protecting our environment from damages caused by over exploitation of indium.

並列關鍵字

Indium ； Oryza sativa ； Indium-tolerant bacterium ； Translocation factor

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