References 參考資料: [1] Logan, A. (2020, April 3). Explained: Cement vs. concrete — their differences, and opportunities for sustainability. MIT News. https://news.mit.edu/2020/explained-cement-vsconcrete-understanding-differences-and-sustainabilityopportunities-0403 [2] Khaiyum, M. Z., Sarker, S., & Kabir, G. (2023). Evaluation of Carbon Emission Factors in the Cement Industry: An Emerging Economy Context. Sustainability, 15(21), 15407. https://doi.org/10.3390/su152115407 [3] Dhami, N. K., Reddy, M. S., & Mukherjee, A. (2013). Biomineralization of calcium carbonates and their engineered applications: a review. Frontiers in microbiology, 4, 314. https://doi.org/10.3389/ fmicb.2013.00314 [4] Konstantinou, C., & Wang, Y. (2023). Unlocking the Potential of Microbially Induced Calcium Carbonate Precipitation (MICP) for Hydrological Applications: A Review of Opportunities, Challenges, and Environmental Considerations. Hydrology, 10(9), 178. https://doi. org/10.3390/hydrology10090178 [5] Carter, M. S., Tuttle, M. J., Mancini, J. A., Martineau, R., Hung, C., & Gupta, M. K. (2023). Microbially Induced Calcium Carbonate Precipitation by Sporosarcina pasteurii: a Case Study in Optimizing Biological CaCO3 Precipitation. Applied and Environmental Microbiology, 89(8). https://doi.org/10.1128/aem.01794-22 [6] Nanyang Technological University. (2022, May 13). Urine, bacteria, and calcium: A green and simple recipe for biocement. https://www.ntu.edu.sg/news/detail/urinebacteria-and-calcium-a-green-and-simple-recipe-forbiocement [7] Xie, J., Yang, Y., Yang, L., & Sun, Y. (2024). Effect of Calcium Carbonate Deposition Induced by Microorganisms and Plant Urease on Sand Reinforcement. Polish Journal of Environmental Studies, 33(3), 2877-2889. https://doi. org/10.15244/pjoes/173166 [8] Melton, L. (2022). How to grow cement. Nature Biotechnology, 40, 286. https://doi.org/10.1038/s41587-02201264-8 [9] Elgendy, I. M., Elkaliny, N. E., Saleh, H. M., Darwish, G. O., Almostafa, M. M., Metwally, K., Yahya, G., & Mahmoud, Y. A. (2024). Bacteria-powered self-healing concrete: Breakthroughs, challenges, and future prospects. Journal of Industrial Microbiology and Biotechnology, 52. https:// doi.org/10.1093/jimb/kuae051 [10] Fahimizadeh, M., Abeyratne, A. D., Lee, S. M., Singh, R. K. R., & Pasbakhsh, P. (2020). Biological Self-Healing of Cement Paste and Mortar by Non-Ureolytic Bacteria Encapsulated in Alginate Hydrogel Capsules. Materials, 13(17), 3711. https://doi.org/10.3390/ma13173711 [11] Anbu, P., Kang, C., Shin, Y., & So, J. (2016). Formations of calcium carbonate minerals by bacteria and its multiple applications. SpringerPlus, 5, 250. https://doi.org/10.1186/ s40064-016-1869-2 [12] Gupta, S., Roy, S., Datta, S., & Datta, S. (2024). Feasibility of Bio-Cementation as a Potential Method for Mitigation of Landslides. Geo-Congress 2024. https://doi. org/10.1061/9780784485316.065 生物水泥的驚人特性 生物水泥最令人驚嘆的特點之一,在於可以透過控制 反應時間、溫度和骨材成分等參數調整其物理特性 [8], 使我們能精準製造具備理想密度、滲透性和結構性能的 生物水泥,以滿足特定的工業需求。 此外,生物水泥還能具有自我修復功能 [9, 10]。某些 細菌產生的孢子能在材料內部長期保持休眠狀態,一旦 出現裂縫,水分和氧就會進入結構內「喚醒」孢子並啟動 修復程序,由內而外合成新的碳酸鈣以填補裂縫。然而, 由於未必每個菌種都能存活於極鹼的環境中,所以研究 人員正尋找合適的保護載體,以提高細菌孢子在混凝土 中的存活率。 以基因工程探索未來方向 為了提高碳酸鈣的產量,科學家正研究透過基因工程 改造S. pasteurii。可能的方向包括將尿素運輸系統移 植至細菌中,若該細菌本身已含有尿素運輸系統,就可以 透過改善現有系統以增加細胞內的尿素濃度 [5]。科學家 亦可以改良S. pasteurii 尿素酶的結構,以提高該酶的 效率 [5];或是透過過量表達尿素酶基因(即增加該基因 的轉錄和轉譯),從而提高這種生物催化劑的濃度 [9]。 生物水泥的潛在用途 生物水泥的自我修復特性使其有望成為未來基建的 理想材料。透過將細菌注入橋樑和城市建築,我們就能 利用細菌主動填補縫隙,防止水分進入並腐蝕內部的鋼 筋結構 [9]。 因此,生物水泥亦是強大的結構修復工具。老舊的水 壩和隧道等大型水底建築往往需承受來自周圍水體的巨 大水壓 [4],將生物水泥注入已發現的裂縫可以鞏固結構, 所產生的不透水碳酸鈣可以有效減弱,甚至截斷建築內 外的水流,防止結構性崩潰 [4, 11]。 另一個可能用途是土壤穩定(soil stabilization)。 鬆散的土壤容易導致侵蝕和山泥傾瀉,微生物誘導碳酸 鈣沉澱作用透過將鬆散的砂粒黏在一起,展現了其預防 土壤侵蝕和山泥傾瀉的潛力,儘管成效亦取決於土壤類 型和斜坡形狀 [4, 7, 12]。 結語 畢竟大自然也花了數百萬年雕琢其獨特工藝,透過改 派細菌上場,我們也許就能建造具自我修復能力的智慧 城市,同時減少消耗稀缺資源。這不是正為「石屎森林」 一詞賦予全新意義嗎? 5
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