PTE考生目前最大的问题之一就是练习题缺乏。除了有限的基本官方书（PLUS，Testbuilder, OG）之外,就没有题了。很多英语基础不是很扎实的同学很难找到练习材料。墨尔本文波雅思PTE培训学校专门为墨尔本，悉尼PTE考生准备了适合PTE听力阅读练习的科学60秒。各位PTE同学可以练习PTE听力中的summarise spoken text和PTE口语中的retell lecture，PTE听力口语-科学60秒-Frosty Moss练习记笔记技巧和复述。废话少说，下面开始：
60秒科学：Microbiome-Studies-Contaminated-by-Sequencing-Supplies
听力内容：
60秒科学节目（SSS）是科学美国人网站的一套广播栏目，英文名称：Scientific American – 60 Second Science,节目内容以科学报道为主，节目仅一分钟的时间，主要对当今的科学技术新发展作以简明、通俗的介绍，对于科学的发展如何影响人们的生活环境、健康状况及科学技术，提供了大量简明易懂的阐释。
In this age of cheap DNA technology, scientists are sequencing every sample they can get their hands on. They’ve ID’d the microbes in mosquito guts, coral mucus and frog skin; in polar ice; even floating in the Earth’s atmosphere. But it turns out some of the bugs reported to belong to those unusual microbiomes could unfortunately be contaminants, from non-sterile lab reagents and DNA extraction kits. So says a study in the journal BMC Biology.
Researchers sequenced a pure sample of just one type of bacteria. But depending which kit they used, which reagents, which lab, their results contained DNA from up to 270 different bacterial strains. Many of those contaminating strains are commonly found on human skin(a lab technician’s, maybe?). Or in soil or water. Which could explain why one recent study turned up soil bacteria in samples of breast cancer tissue, the researchers say. Another study found that infants’ throat bacteria change as they get older. But these researchers say the changing bacterial communities in that study were due not to age but to changing the brand of DNA kit over time.
Study author Alan Walker, of the University of Aberdeen, says contamination is only a problem if you’re working with samples that aren’t already rich in bacteria. “If you’re doing fecal work, for example, this probably doesn’t concern you, because there’s enough DNA coming from the actual sample that it’ll drown out any of the background contamination.” His recommendation for scientists? Alongside the actual samples, try sequencing nothing¡to see what sort of shadow microbiome is already lurking in your lab.
