品味什么作文800字:细菌也能清洁牙齿

研究者发现了对抗蛀牙的新型武器：口腔细菌合成的一种酶可以防止牙菌斑的生成。这项发现可以利用人体自身存在的对抗牙菌斑的物质，以促进牙膏的开发。

The human mouth is awash with bacteria. More than 700 species thrive in the hot, moist conditions, including Streptococcus mutans, one of the main components of plaque. Clinging to the teeth in thin layers called biofilms, S. mutans digests sugars and produces acids that can eat into enamel and cause cavities. Other bacteria are more gracious guests. In 2009, for example, scientists found that S. salivarius, a type of bacterium found on the tongue and other soft tissues in the mouth, decreases the buildup of S. mutans biofilms. 

人类的口腔遍布细菌。超过七百种细菌在口腔温暖而湿润的环境中生长繁殖，其中包括牙菌斑的主要成分之一变异链球菌。它们形成一层薄的生物膜黏附在牙齿表面，代谢糖类产酸，腐蚀牙齿的珐琅质形成蛀牙。口腔中的另细菌则是彬彬有礼的客人。例如在2009年，科学家发现了唾液链球菌，它存在于舌头和口腔其他软组织中，能够消减变异链球菌形成的生物膜。1

Hidenobu Senpuku, a biologist at the National Institute of Infectious Diseases in Tokyo, and colleagues wanted to know what substance conferred S. salivarius's cavity-fighting powers. Using chromatography, a method that divides the molecules in a mixture based on charge or size, they separated out individual proteins from samples of the microbe. The scientists then mixed each kind of protein with S. mutans cells and measured which cultures grew the smallest amount of biofilm on plates in the lab. The protein FruA, an enzyme that breaks apart complex sugars, was the most powerful biofilm blocker. 

东京市日本国家传染病研究院的生物学家Hidenbu Senpuku和他的同事想了解一下是什么物质赋予了唾液链球菌抗蛀牙的能力。研究者利用层析法——一种根据电荷或大小将混合物中的各种分子分离开来的方法，把各种不同的蛋白质从唾液链球菌的样品中分离出来。然后，研究者将每一种蛋白跟变异链球菌混合，测量哪种培养方式在培养基上形成的生物膜最薄。FruA蛋白是一种可以分解复合糖的酶，它是效力最大的生物膜阻断剂。

The researchers also found that a form of FruA, produced by the common fungus Aspergillus niger and available off-the-shelf, stymies plaque equally well. This commercial FruA worked despite the fact that its amino acid sequence is somewhat different from that of S. salivarius FruA. That might speed the development of toothpastes that include FruA, says Senpuku. 

研究者还发现有一种现成的FruA，由普通真菌黑曲霉产生的，它在防止牙斑形成方面有着同样好的效果。尽管这种商品化的FruA的氨基酸序列跟唾液链球菌FruA的氨基酸序列有一定的差异，但它确实有用。Hidenbu Senpuku表示，这样可能会使含有FruA的牙膏迅速开发出来。
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The findings, reported in Applied and Environmental Microbiology, are not a license to eat all the candy you want, however. When researchers increased the concentration of sucrose, a type of sugar, in mixtures containing S. salivarius FruA and S. mutans, the beneficial bacterium lost its ability to prevent biofilm formation. The authors write that this observation may help explain why a 1996 study found that FruA contributed to cavity formation in rats. 

这些研究结果发表在了《应用与环境微生物学》杂志上，但这并不意味着准许你去吃所有你想吃的糖。当研究人员在唾液链球菌FruA和变异链球菌的混合物中增加蔗糖的浓度之后，这种有益的细菌失去了阻止生物膜形成的能力。论文作者该提出，这项观测结果可以解释为什么1996年的一项研究发现FruA促进大鼠蛀牙的形成。

Mary Ellen Davey, a microbiologist at the Forsyth Institute in Cambridge, Massachusetts, agrees that the findings could spur the development of better toothpaste. But she says that won't be an easy task. Finding "the formulation that would 'guarantee' that the enzyme remained enzymatically active on the shelf of your favorite drug store is a big challenge," she says.

马萨诸塞州剑桥福尔塞斯研究所的微生物学家玛丽·艾伦·戴维认可该发现会促使人们开发出更好的牙膏。然而，她认为开发更高品质的牙膏并非易事。“你所面临的一大挑战是如何找到一个配方，保证牙膏中的这种酶在你最喜欢的杂货店货架上仍然具有活性”，戴维说。