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Functional and molecular biodiversity of the bacterial production of the climate-changing gas dimethyl sulphide.

改变气候的气体二甲硫醚的细菌生产的功能和分子生物多样性。

基本信息

批准号：
NE/E018033/1
负责人：
Andrew Johnston
金额：
$ 35.55万
依托单位：
University of East Anglia
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FE018033%2F1
关键词：
Functional molecular biodiversity bacterial production

项目摘要

We've all been to the seaside and we've all been told by a knowing parent to 'breathe in that ozone', because it's 'good for you'. Well, firstly, it's not ozone and second, it's not terribly good for you. That distinctive aroma is, in fact another gas, called dimethyl sulphide (DMS) and it has been known since 1971 that it is hugely important, with some 30 million tons of it being liberated into the air, world wide, every year. And once in the atmosphere it has other major effects, being the 'seed' that sets off cloud formation over the oceans. Indeed, the production of this molecule is on such a scale that it has major effects on the world's climate, thanks to its effect on the cloud cover over the oceans. Yet, despite all this, we have only very recently begun to understand, at a molecular level, how this process occurs. This is all the more surprising since we have known for some time that many marine bacteria, some of which are easy to grow on the lab, can liberate DMS if supplied with the key precursor molecule, called Dimethylsulphiopropionate - DMSP for short. Not a compound one reads about every day, yet there are over two billion tonnes of it in the world's oceans, seas and seashores. That's the weight, give or take, of another seaside symbol, the Blackpool Tower - 70,000 times over. Amazing. The DMSP is used by the great masses of marine plant life - seaweeds and microscopic plankton - as a buffer, or osmo-protectant, against the saltiness of the sea, and against other stresses. When these plants die, some of the DMSP that escapes from them is used as food by some marine bacteria and, when they do so, they convert some of it to that DMS gas in the process. We recently isolated one such DMSP-consuming bacterium, called Marinomonas, from the Norfolk coast. We used various molecular techniques to get our hands on some of the genes that are involved. By looking at their sequences, we could guess what the genes might be doing and, so far, it looks as if the mechanisms are very different from those hypothetical ones that had been proposed before. We also saw that very similar genes exist in some other, very unexpected, types of bacteria, such as those that live, symbiotically, on the roots of land plants. So the extent of DMS production by bacteria may be far wider and varied than we had thought. It was also very striking that other bacteria that are known to make the DMS gas from DMSP do not contain the gene that we discovered in 'our' strain of Marinomonas. So, there must be some fundamentally different ways in which different bacteria can break down DMSP. We now plan to sample all sorts of environments that are known to be very rich in DMSP and to isolate DMSP-degrading bacteria in a search for these 'novel' forms of DMS emission. These environments will range from the mouths of giant clams, to the roots of some plants in Hawaii, to the open seas (especially when they have just had a massive 'bloom' of tiny plankton cells that liberate huge amounts of DMSP in their death throes) and also the root surfaces of some of the land plants that exude DMSP. We will also look for the genes in some of the bacterial species that are already known to be DMS producers, but which do not have the genes that we had identified in Marinomonas. All this will let us amass a genetic inventory of the different ways in which this climate-changing process occurs in different bacteria. So, in the not-too-distant future, we, and others, can use this information to make molecular tools that will allow us to investigate, even more thoroughly, the biodiversity that underpins the smell of the seaside.

我们都去过海边，我们都被一位知情的父母告知要“呼吸臭氧层”，因为它“对你有好处”。嗯，首先，它不是臭氧，其次，它对你不太好。事实上，这种独特的气味是另一种气体，称为二甲基硫（DMS），自1971年以来，人们就知道它非常重要，每年全世界约有3000万吨二甲基硫被释放到空气中。一旦进入大气层，它就会产生其他主要影响，成为引发海洋上空云层形成的“种子”。事实上，这种分子的生产规模如此之大，以至于它对世界气候产生了重大影响，这要归功于它对海洋上空云层的影响。然而，尽管如此，我们直到最近才开始在分子水平上了解这一过程是如何发生的。这更令人惊讶，因为我们已经知道一段时间了，许多海洋细菌，其中一些很容易在实验室中生长，如果提供关键的前体分子，称为二甲基硫基丙酸-DMSP简称，可以释放DMS。并不是每天都会读到的化合物，但世界海洋和海岸中却有超过20亿吨的化合物。这是另一个海滨象征，布莱克浦塔的重量，大约是它的7万倍。棒了DMSP被大量的海洋植物--海藻和微小的浮游生物--用作缓冲剂，或者说是植物保护剂，以抵御海水的盐度和其他压力。当这些植物死亡时，一些从它们中逃逸出来的DMSP被一些海洋细菌用作食物，当它们这样做时，它们在这个过程中将其中一些转化为DMS气体。我们最近从诺福克海岸分离出了一种这样的消耗DMSP的细菌，叫做海洋单胞菌。我们使用了各种分子技术来获得一些相关的基因。通过观察它们的序列，我们可以猜测这些基因可能在做什么，到目前为止，看起来这些机制与以前提出的假设机制非常不同。我们还发现，非常相似的基因存在于其他一些非常意想不到的细菌类型中，例如那些共生地生活在陆地植物根部的细菌。因此，细菌产生二甲硫醚的程度可能比我们想象的要广泛得多。同样令人惊讶的是，其他已知能从DMSP中产生DMS气体的细菌并不含有我们在“我们的”海洋单胞菌菌株中发现的基因。因此，不同的细菌分解DMSP的方式肯定有本质上的不同。我们现在计划对已知DMSP含量非常丰富的各种环境进行采样，并分离出DMSP降解细菌，以寻找这些“新”的DMS排放形式。这些环境的范围将从巨蛤的嘴，到夏威夷的一些植物的根部，到公海（特别是当它们刚刚有一个巨大的"绽放"的微小浮游生物细胞，释放出大量的DMSP在他们的垂死挣扎），也是一些陆地植物的根表面，散发出DMSP。我们还将在一些已知是DMS生产者的细菌物种中寻找基因，但这些细菌物种不具有我们在海洋单胞菌中发现的基因。所有这些将使我们积累一份基因清单，了解这种气候变化过程在不同细菌中发生的不同方式。所以，在不久的将来，我们和其他人可以利用这些信息来制造分子工具，使我们能够更彻底地调查支撑海边气味的生物多样性。