A team of researchers dug into 60 different people’s belly buttons and turned up bacterial diversity and microbial mystery. All in all, they identified more than 2, 000 species of bacteria as well as two species of archaea, the ancient predecessors of bacteria. Some of the species frequently occurred in multiple belly buttons, while others were confined to just a few participants. According to The Scientist:
Each volunteer harbored an average of 67 different types of bacteria, and the vast majority of the 2, 188 species found were only present in six or fewer belly buttons. One of the volunteers, Dunn said, had not bathed in years, which yielded a belly button sample that not only had bacteria present, but two species of archaea, which were rare in the study.
The researchers are stumped over what causes this diversity and difference. Writing in Scientific American’s guest blog, the study’s lead author, Rob Dunn, ponders the mystery:
We began to more seriously wonder what explained the differences from one person to the next. We were finding hundreds and then thousands of species, many of which appear new to science. They included strange species, such as one species found on my body that appears to prefer to break down pesticides.
One can imagine many factors that influence which bacteria are on your skin; whether you were born c-section or vaginally, gender, age, weight, whether you are an innie or an outie, whether you live in a city or the country, what climate you live in, whether or not you have a dog, and maybe even where you grew up or where your mother lived when she was pregnant with you.
一个繁茂的细菌群落正生长在你的肚脐里
一组研究人员探查了60个人的肚脐后，发现了其中细菌的多样性和神秘性。总的来说，他们辨认出了2000多种细菌，还有2种古生菌（细菌的古老前辈）。其中一些细菌频繁地出现在多人的肚脐中，其他的细菌则只在少数几个参与者的肚脐中现身。据《科学家》杂志介绍：
共发现了2188种细菌，平均每位志愿者携带67种。这些细菌中的绝大部分只在6位或者更少的志愿者的肚脐中出现。一位名为邓恩的志愿者自称几年没有洗澡，在他的肚脐中不仅发现了细菌，还发现了在研究中很罕见的2种古生菌。
研究人员正在探求造成如此多样性和差异性的原因。这项研究的首席作者——罗布·邓恩，在《科学美国人》的特邀博客上写道：
我们开始更严肃地探求造成此差异性的原因。我们发现了成百上千的细菌种类，其中很多种类在科学界是首次被发现。这些首次亮相的细菌中有一些很特别，比如在我的肚脐里找到的一种细菌似乎更喜欢分解杀虫剂。
关于哪些细菌会出现在你的皮肤上，你可以猜想出许多会产生影响的因素：你是自然生产的还是剖腹产的，你的性别、年龄、体重，你的肚脐是内凹的还是外凸的，你住在城市还是乡村，你的居住地的气候，你是否养狗，甚至于你在哪里长大或者你的母亲在怀着你的时候住在哪里。
研究团队从北美各地采集到了600多个新的肚脐样本，他们正寄望于由这些样本获取到的数据能够解开这个谜团。值得一提的是，他们还没有触及潜伏在我们鼻子、眉毛、脚趾甲和腋窝中的细菌森林呢，至少现在还没有。
