喜欢雨的味道吗?

喜欢雨的味道?

If you've lived outside a major city, the smell is instantly recognisable – the earthy scent of petrichor as rain hits dry soil. Now, new research has uncovered why it's not just us humans who are attracted to this incredibly pleasant odour.

如果你住在大城市以外的地方，你会立刻闻到一种叫petrichor的泥土味，那是雨水打在干燥的土壤上的味道。现在，新的研究揭示了为什么不仅仅是我们人类会被这种令人难以置信的香味所吸引。

That luscious smell we can detect after rain comes from an organic compound called geosmin, which is produced by microbes, including the bacteria genus Streptomyces.

雨后我们能闻到的甜美气味来自一种叫土臭素的有机化合物，它是由包括链霉菌属在内的微生物产生的。

We also know that Streptomyces releases geosmin when they die, and that humans and other creatures are particularly attuned to it. The question, of course, is - why does this happen?

我们也知道链霉菌死后会释放土臭素，而人类和其他生物对土臭素尤其敏感。当然，问题是，为什么会这样?

An international team of researchers set out to explain why bacteria produce geosmin, and whether any other creatures were able to enjoy the smell as much as we do.

一个国际研究小组着手解释为什么细菌会产生土臭素，以及其他生物是否能像我们一样享受这种气味。

To investigate possible roles of geosmin and other Streptomyces volatile organic compounds in the context of soil ecosystems, we asked whether the smell of Streptomyces spp. might attract soil-dwelling arthropods, the international team of researchers wrote in their new paper.

“为了研究土臭素和其他链霉菌的挥发性有机化合物在土壤生态系统中的可能作用，我们提出了这样一个问题:链霉菌的气味是否会吸引住在土壤中的节肢动物，”国际研究团队在他们的新论文中写道。

And that's exactly what they found.

这正是他们所发现的。

In a network of field traps baited with Streptomyces coelicolor colonies, we found significant attraction of springtails (Collembola) compared with control traps.

“在一个以彩色链霉菌菌落为诱饵的田间诱捕网中，我们发现与对照诱捕相比，弹尾具有显著的吸引力。”

The team did a number of experiments both in the field and in the lab to see the effects of geosmin and another compound called 2-methylisoborneol (2-MIB) on forest creatures, particularly springtails - tiny arthropods with a tail-like appendage, which live in organic materials such as leaf litter on a forest floor.

团队做了很多实验场和在实验室看到geosmin的影响和另一种化合物称为2-methylisoborneol (2-MIB)森林生物,特别是跳虫——微型节肢动物尾巴肢,它生活在有机材料,如落叶在森林的地面上。

Turns out that springtails are big fans of geosmin. They can sense it with their antennae, are attracted to it, and will feed on the Streptomyces producing it.

事实证明，弹尾虫是土臭素的超级粉丝。它们可以用它们的触须感知它，被它吸引，并以产生它的链霉菌为食。

But why would a bacterium go to so much effort just to be slurped up by an arthropod? Although producing a nice smell to get eaten might sound like a bad time for most, Streptomyces actually has a plan.

但为什么细菌要费这么大力气才能被节肢动物吃下去呢?虽然对大多数人来说，产生一种好闻的味道来吃听起来不是一个好时机，但链霉菌确实有一个计划。

Streptomyces acts, in a lot of ways, like a fungus. It looks a lot like a filamentous fungus, and when it is ready to reproduce, it creates spores, which can spread newborn bacteria far and wide.

链霉菌在很多方面都像真菌。它看起来很像丝状真菌，当它准备繁殖时，它会产生孢子，这些孢子可以将新生的细菌传播到四面八方。

But it does need a vector for that spread, which is where the springtails come in.

但它确实需要一个传播的矢量，这就是弹尾的作用。

[A springtail] feeds on the Streptomyces colonies and disseminates spores both via faecal pellets and through adherence to its hydrophobic cuticle, the team explains.

“(弹尾虫)以链霉菌菌落为食，通过粪球和附着在疏水性表皮上传播孢子。”研究小组解释说。

The results indicate that geosmin and 2-MIB production is an integral part of the sporulation process, completing the Streptomyces life cycle by facilitating dispersal of spores by soil arthropods.

“结果表明，土臭素和2-MIB的产生是孢子形成过程中不可或缺的一部分，通过促进土壤节肢动物孢子的扩散，完成了链霉菌的生命周期。”

Next time you smell the rain, you can enjoy the fact that what you're smelling is an entire circle of life in its own little way.

下次当你闻到雨的味道时，你就会享受到这样一个事实:你所闻到的是一个完整的生命循环。

The research has been published in Nature.

这项研究发表在《自然》杂志上。