Emerging Technologies（在线收听）

Emerging Technologies

2

Bacterial factories

By Erika Jonietz

In the valleys of central China, a fernlike weed called sweet wormwood grows in fields formerly dedicated to corn. The plant is the only source of artemisinin, a drug that is nearly 100 percent effective against malaria. But even with more farmers planting the crop, demand for artemisinin exceeds supply, driving its cost out of reach for many of the 500 million afflicted with malaria every year. Bioengineer Jay Keasling aims to solve the supply problem—and drastically reduce the cost of treatment—by mass-producing the compound in specially engineered bacteria.

Keasling’s efforts are an example of metabolic engineering, a field in which researchers try to optimize the complex processes whereby a cell produces or breaks down a particular substance. These processes rely on the stepby-step direction of genes. Changing even one gene can alter the outcome. Most metabolic engineering has previously focused on modifying a cell’s natural processes by inserting, mutating or deleting a few key genes. According to James Collins, a biological engineer at Boston University, “what Jay is doing is a bit more radical”: creating entirely new metabolic pathways by integrating multiple genes from different organisms into a host microbe.

Ultimately, Keasling believes, new technologies for analyzing and understanding cellular pathways will enable researchers to engineer microbes to produce a huge range of chemicals, from drugs to plastics. Unlike conventional chemical engineering, bacteria do their job cleanly, without requiring or producing environmentally harmful compounds. “We’ve got all these great tools,” Keasling says. “Now we can start to put these to use to solve this one particular problem: how to engineer a cell to do the kinds of chemistries that you want it to do.”

Vocabulary Focus

drastically (adv) [5drAstikli] severely and suddenly or with very noticeable effects

optimize (v) [5Cptimaiz] to make something as good or effective as possible

integrate (v) [5inti^reit] to combine two or more things in order to become more effective

Specialized Terms

malaria (n) 疟疾 a disease cause by the bite of a particular type of mosquito, which causes periods of fever, coldness and shaking, and is common in many hotter parts of the world

mutate (v) 使突变 to permanently change a gene in order to develop new physical characteristics

microbe (n) 微生物 a very small living thing, especially one which causes disease and which is too small to see without a microscope

新兴科技

2

细菌工厂

中国中部的山谷，一种名为香苦蒿、貌似羊齿植物的草丛生长在昔日的玉米田间。青蒿素是治疗疟疾几乎百分之百有效的良药，而香苦蒿就是其唯一来源。不过，纵然已有较多的农民种植香苦蒿，青蒿素仍然供不应求，使得价格飙涨，超出每年罹患疟疾5亿人口中许多人的负担范围。生物工程师杰伊·吉斯林一心想解决供应短缺问题，以大幅降低治疗成本，她的方法是利用特别设计的细菌，大量生产青蒿素这一化合物。

吉斯林的努力是代谢工程的一例。代谢工程领域的研究人员设法尽可能改善细胞生产或分解特定物质的复杂过程，这些过程依赖各基因的逐步引导，即使只改变一个基因也可能影响整个结果。多数的代谢工程之前均致力于植入、删除一些关键基因或使关键基因突变，以更改细胞的自然生产及分解过程。波士顿大学生物工程师詹姆斯·科林斯说：“杰伊的做法更激进一点”，将来自不同有机体的多个基因整合至宿主微生物，好创造出崭新的代谢路径。

吉斯林相信，用于分析及了解细胞路径的新技术最终可使研究人员设计出微生物，进而生产从药品到塑料等广大范围的化学制品。与传统化学工程不同的是，细菌的代谢工程较为干净，不需要也不会产生对环境有害的化合物。吉斯林说：“我们有这些很棒的方法，现在可以开始用它们来解决这个问题：如何设计一个细胞来做你希望它完成的化学程序。”