Pass the Bacteria, Please!

　　请把细菌递给我

　　Bacteria are terribly good for you. So say the promoters of a rapidly growing industry in “probiotic” products. The title “probiotic” (for life) is technically reserved for those food products containing living cultures of “good” microorganisms. Just how good are they? It depends on to whom you are listening.

　　“Microbic marketing” is highly competitive; many brands of yogurts, many yogurt drinks, and many capsules of live bacteria are on display －all promising to be good for you! Promotions are intense, and the questions are many. Do healthy people need cultures of bacteria when they already have a crowd of fine bacteria at work? How valid are the claims that probiotic products increase the health of intestinal cells, degrade toxins, or prevent cancer? There is yet no scientific consensus, and for now, consumers must decide for themselves.

　　The recent interest in probiotic products has grown out of a concern for the side effects of antibiotics in the 1950s. Since antibiotics are not very selective as to which bacteria they attack, those prescribed for a toothache can quickly wipe out a whole population of intestinal microbes. Bacteria contained in fermented-milk products appeared to be effective in restoring populations of the beneficial bacteria after such a catastrophe. In the development of probiotic products, different species of Lactobacilli and Bifidobacteria are selected according to their abilities to produce yogurt, to survive passage through the digestive tract, and to establish themselves in their new environment by out-competing potentially unfriendly microbes for space and nutrients. This last criterion is not always easy to measure.

　　Cultures of yogurt, according to the National Yogurt Association, must contain at least 100 million live bacteria per gram. (Check to see how many bacteria are in one serving of your favorite yogurt.) It’s a big number, but it is impossible to know how many will loiter in your digestive system. Research now is underway to determine whether probiotic products might take the place of controversial antibiotics in livestock feed, or if bacterial/antibacterial compounds might be useful as food preservatives. Probiotics is about using bacteria to control other bacteria!

　　“前生命期”产品的产业在迅速发展，它的倡导者说细菌对你是大有好处的。“前生命期”这一名称是指包含“有益的”微生物培养菌的食品。它们的益处到底有多大呢？这取决于你在听谁说。

　　“微生物产品营销”的竞争非常激烈。许多种品牌的酸奶、酸奶饮料和多种真菌胶囊都在展示之中——它们都被说成会对你的身体有好处。促销活动密集，而留给人们的疑问也是很多的。健康人的体内有众多有益的微生物在活动。那么他们是否还需要培养菌呢？有人声称“前生命期”产品会促进大肠内细胞的健康生长，使毒素降解并防止癌症的发生。这种说法的可靠性有多大呢？对于这些问题，科学界还没有统一的认识。消费者必须自己做出决定。

　　人们最近对“前生命期”产品的兴趣来源于50年代开始的对抗生素副作用的担心。因为抗生素对它要对抗的细菌没有很大的选择性，为治牙疼而开出抗生素可能会很快杀死一大批大肠中的细菌。在这场劫难过后，含在发酵奶产品中的细菌似乎能有效地恢复那些有益的细菌的数量。在开发“前生命期”产品的过程中，根据它们能制造酸奶的能力，人们选择不同种的乳酸杆菌素和双线菌素，想使它们通过消化道后仍然能够存活下来。并且在新的环境里，它们通过与可能有害的细菌争夺营养和空间得以立足。但有害和有益的最终标准并不是那么好确定的。

　　根据美国国家酸奶协会的说法，每一克酸奶中的培养菌至少含有一亿个真菌。（查看一下，在你最喜欢吃的酸奶中，每一份中含多少真菌）。这个数字是很大的，但你不可能知道有多少真菌只是在你的消化系统中闲逛。人们现在正在进行研究，目的是要确定“前生命期”产品是否能够取代有争议的牲畜饲料中的抗生素，或者细菌或抗菌化合物是否可以用在食物防腐剂当中。前生论是研究用细菌来控制细菌的科学。

　　Bacteria Bonus

　　Under the right conditions, bacteria can grow very fast indeed. It has been calculated that with sufficient food, one cell of E. coli bacteria could theoretically produce a mass of bacteria greater than the mass of the Earth in just three days! It誷 no surprise that between one-third and one-half of our feces are composed of bacteria!

　　细菌的好处

　　在合适的条件下，细菌可以生长得很快。据估算，如果有足够的食物，大肠杆菌的一个细胞理论上可以在三天内产生出一大群细菌，比地球的体积还要大。所以，我们的粪便中的1/3到1/2是细菌。这一点也不奇怪。

　　Enzyme—Any of numerous proteins produced by living organisms that function to start or speed up a reaction without being modified in the process.