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(第一期-8)Friendly bacteria move in mysterious ways

(2011-11-09 19:36:07)
标签:

杂谈

分类: 实用译苑

Probiotic yoghurts have only a small effect on gut bacteria.

神秘的有益菌-益生菌酸奶肠道细菌的影响其实很小 -                                

Ed Yong
艾德.杨

Probiotic yoghurts seem to have little effect on the population of bacteria in the human gut.Many yoghurts are loaded with live bacteria, and labelled with claims that consuming these microorganisms can be good for your health. But a study published today shows that such yoghurts have only subtle effects on the bacteria already in the gut and do not replace them.

益生菌酸奶似乎对人类肠道细菌没有多大影响.酸奶含有大量的活细菌.包装上声称这些微生物会对你的健康有益.但今天公布的一份研究表明,这样的酸奶对肠道已存在的细菌只有细微的影响而且不能替代他们。

Nathan McNulty, a microbiologist at Washington University in St Louis, Missouri, recruited seven pairs of identical twins, and asked one in each pair to eat twice-daily servings of a popular yoghurt brand containing five strains of bacteria.

密苏里州圣路易斯的华盛顿大学微生物学家,内森.麦克努提, 招募了七对同卵双胞胎志愿者,每一对中选一人,一日两次,吃一份含5个菌株的受大众欢迎的品牌酸奶。

By sequencing bacterial DNA in the twins' stool samples, the team showed that the yoghurt microbes neither took up residence in the volunteers' guts, nor affected the make-up of the local bacterial communities.

经过细菌DNA测序双胞胎的粪便样本,研究小组发现酸奶的微生物既没有能在肠道中驻扎,也未能对肠道中固有的菌群结构产生影响。

Jeffrey Gordon, the microbiologist at Washington University who led the study, was not surprised. "We were only giving several billion bacterial cells in total to the twins, who harbour tens of trillions of gut microbes in their intestines," he says.

领导这项研究的华盛顿大学微生物学家杰弗里·戈登对此并不惊讶。“我们只是在这对双胞胎的含有数万亿微生物的肠道内,给了总共几十亿的细菌细胞,”他说。

Murine model
鼠模型

McNulty also fed the five bacterial strains from the yoghurt to 'gnotobiotic' mice — animals raised so that the only microorganisms that their guts contain are 15 species found in humans.
麦克努提也给限菌处理的实验鼠同样喂食酸奶中的5个菌株.---培养的限菌老鼠的肠道中仅含有人类中发现的15种微生物.


As with the twins, the yoghurt bacteria did not change the composition of the rodents' resident communities. However, the activity of genes that allow the native bacteria to break down carbohydrates did increase. One of the five yoghurt strains — Bifidobacterium 双歧杆菌属animalis lactis — also showed a similar boost in its ability to metabolize carbohydrates.


和双胞胎组的实验一样,酸奶没有改变啮齿动物们的细菌群落结构。然而,原有细菌分解碳水化合物的基因活力确实增加了。5株酸奶菌株中的一株---双歧杆菌---其代谢碳水化合物的能力也同样显著增强。

The study, which was funded by the US National Institutes of Health and Danone Research, the research arm of the food company that makes some probiotic yoghurts, was published in Science Translational Medicine.

这项研究报告发表在医药科学译文杂志。其研究基金是美国国立卫生研究院和达能研究所(一所研究益生菌酸奶食品公司的研究机构)共同提供。

Companies that sell foods with added ingredients that are intended to boost health or prevent illness are under increasing pressure to substantiate the claims about their products. The pressure was increased earlier this year, when the European Food Safety Agency criticized many products, following an extensive three-year review.
出售含食品添加成分以促进健康和预防疾病的公司,为证实它们的产品功效,正在承受着越来越大的压力。今年早些时候,这种压力又增加了。欧洲食品安全局在进行了为期三年的广泛的审查后,对很多产品进行了点名批评。

The health claims are hard to test, says Gordon, because there is so much variety in the bacteria in the yoghurts and in the people who consume them, but gnotobiotic mouse models will be vital for such studies. Using the mice, he can examine the effect of probiotic foods under tightly controlled conditions, with "defined communities where all the actors and genes are known". The mouse models "provide a foundation for critically evaluating the claims from manufacturers of functional foods and probiotics", he says.

保健作用难于测试,戈登说,因为在酸奶中和消费者体内细菌种类纷繁复杂。但限菌小鼠模型这样的研究至关重要。利用老鼠,你能在严格控制的条件下测试含有益生菌的食品的功效。因为在所定义的环境中所有参与成分和基因都是我们已知的。“老鼠模型提供了一个基础平台以精细地评价厂商所声称的功能性食品及益生菌的功效”,他说。


More twins needed It's too early to be drawing conclusions, say other researchers.

需要更多的双胞胎志愿者做实验,现在得出结论还为时过早,其他的研究者说。

Dusko Ehrlich, a microbiologist at the French National Institute for Agricultural Research (INRA), thinks that the team did not look at enough twins, or sequence their bacterial genes at enough depth. "We should reserve the judgement on the effects of probiotics in humans until broader and deeper studies are carried out," he says.

在法国国家研究所(INRA)从事微生物农业研究的科学家杜司科.埃里奇认为,该研究小组未能察看足够数量的双胞胎,或者他们的细菌基因排序未能涉及足够的深度。“在益生菌对于人类的影响进行更加广泛和深入地研究之前,我们进行判断应该谨慎”他说。

Jens Walter, a microbiologist at the University of Nebraska-Lincoln calls the work an "impressive technical achievement". However, he cautions that there are limits to studying mice with human gut bacteria, because different species have their own specifically evolved sets.


詹斯沃特,一个内布拉斯加州林肯大学的微生物学家称此为“出色的技术成就”。然而,他提醒说,在小鼠身上研究人类肠道细菌也有其局限性,因为不同的物种有其自身特别的演化背景。


McNulty acknowledges the problem. But, he says, "we're always looking to refine these mouse models to be more like the human context. The fact that we see shared responses in mice and humans is good evidence that we're doing something right."
麦克努提承认有这个问题。但是,他说,“我们一直在精细调整这些小鼠模型使其变得更像人类的环境。事实上,我们看到老鼠和人类有着共同的反应。这充分的证明我们正在走的是正确的道路。”


Gordon now wants to find out exactly how the ingested microbes influence the entrenched ones. "These are very dynamic systems with a lot of cross-talk," he says. "We don't know the nature of the conversation that's occurring."


戈登现在要具体地弄清外来微生物是如何影响体内的原生菌的。"这些变幻复杂的系统间需要有大量的信息交换,”他说。“我们尚不清楚所发生的信息交换的本质。

 

 

译者:重黎

翻译时间:2011.11.9.

原文链接:http://www.nature.com/news/2011/111026/full/news.2011.614.html

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