Hard to digest

　　不好消化(陳繼龍 編譯)

　　Jun 2nd 2006

　　From The Economist print edition

　　BACTERIA, like people, can be divided into friend and foe. Inspired by evidence that the friendly sort may help with a range of ailments[1], many people c________① bacteria in the form of yogurts and dietary supplements.(1) Such a smattering[2] of artificial additions, however, represents but a drop in the ocean. There are at least 800 types of bacteria living in the human gut. And research by Steven Gill of the Institute for Genomic Research in Rockville, Maryland, and his colleagues, published in this week's Science, suggests that the collective genome of these organisms is so large that it contains 100 times as many genes as the human genome itself.

　　細(xì)菌和人一樣也有敵我之分。有益的細(xì)菌有助于防治多種疾病已經(jīng)得到證實(shí)，這使得許多人都食用細(xì)菌制成的酸奶以及補(bǔ)品。然而，人為地補(bǔ)充這么一點(diǎn)點(diǎn)，只能是杯水車薪。人消化道內(nèi)生活著至少800種細(xì)菌。馬里蘭州洛克威爾基因組研究中心的史蒂文·吉爾及其同事們在本周《科學(xué)》雜志上發(fā)表的一篇研究報告認(rèn)為，這些生物體有著龐大的宏基因組，所包含的基因總數(shù)是人類基因組的100倍。

　　Dr Gill and his team were able to come to this conclusion by extracting bacterial DNA from the faeces of two volunteers. Because of the complexity of the samples, they were not able to reconstruct the e_______② genomes of each of the gut bacteria, just the individual genes. But that allowed them to make an estimate of numbers.

　　吉爾博士和他的研究小組是通過提取兩位志愿者糞便中的細(xì)菌DNA后得出這一結(jié)論的。鑒于標(biāo)本的復(fù)雜性，他們無法重建消化道所有細(xì)菌的全部基因組，而只構(gòu)建了個別基因。但這使得他們能夠?qū)�基因總�?shù)作出估計。