Making and breaking DMS by salt marsh microbes - populations and pathways, revealed by stable isotope probing and molecular techniques

盐沼微生物制造和破坏 DMS - 通过稳定同位素探测和分子技术揭示的种群和途径

基本信息

批准号：
NE/H008586/1
负责人：
Andrew Johnston
金额：
$ 19.04万
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：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH008586%2F1
关键词：
Making breaking DMS salt marsh

项目摘要

There is an evocative gas, called dimethyl sulfide - DMS for short - which most of us have smelled, since it is a component of the smell of the seaside. But it is far more important than that. Around 300 million tons are made each year by marine microbes, around 10% of which escapes into the atmosphere. Not only does this bring back memories of days by the sea, but DMS is chemically modified in the air to compounds that cause clouds to form over the oceans, affecting weather and climate. And, when it rains, these compounds come back to earth in a major step in the global circulation of the essential element sulfur. And one more thing. Even in tiny amounts, DMS attracts different marine animals - fish, penguins and tiny crustaceans all swim, fly or paddle towards it as fast as they can. The reason is that they know that where there is DMS there is food. This is because DMS is a by-product of biochemical processes that occur when different microbes devour another sulfur-containing molecule, with a ridiculously long name - dimethylsulfoniopropionate. This DMSP is made in prodigious amounts by tiny plankton organisms in the oceans, by seaweeds and by a very few land plants that live by the sea. At UEA, we discovered how microbes make the DMS and in Warwick, the ways in which other marine microbes can further transform this gas are studied. We use molecular biology, gene cloning and DNA sequencing to identify the genes in a whole range of microbes that let them undertake these reactions. For both processes, we found that some very unexpected organisms can make or can break down DMS and that they can do this in completely different and surprising ways. Most of these studies are on purified strains that we grow in the lab. This lets us identify the genes and their individual functions, but it does not tell us which are the most important pathways and which of the microbes are the key players in natural environments. This is because the great majority of bacteria that live 'out here' in the natural world have never been cultured. Luckily, some very recent techniques let us study such 'difficult' microbes. One neat trick, invented by Professor Murrell, is to feed natural populations of microbes with a version of the substrate that is chemically identical to the normal one but which is, literally, heavier. So, in our case, we will use forms of DMS and DMSP in which the carbon atoms have an atomic weight of 13, not the more conventional 12. When a microbe digests such a heavy molecule, the heavy carbon is incorporated into its molecules, including DNA. By purifying this heavy DNA from the light form and by looking for signature sequences in the genes, the microorganisms and fungi that used the DMS or the DMSP can be identified and the mechanisms by which they do so can be inferred. We will do these experiments on mud from the salt marshes of North Norfolk. These are home to the grass Spartina, one of the few land plants that makes DMSP. This plant is also important because it is has been spread by human hand across the world and is now a serious pest on many coasts all over the world, killing off many native species. Not surprisingly, there is a lot of DMSP around Spartina roots, which teem with bacteria and fungi that consume or make DMS. We will therefore conduct a census of these microbes, some of which may be new to science. Our findings should relate to other hotspots for DMS and DMSP, such as corals and the massive blooms of plankton in the oceans. Although very small, the sheer numbers of microbes mean that they affect our environment more than most of us realise. Given the environmental consequences of the DMS gas, it is important to know which types of bacteria and fungi that affect its production and destruction and which of the various potential pathways are involved. This may help us model how environmental changes such as climate change alter the balance of these processes.

有一种令人回味的气体，称为二甲基硫化物-DMS的短 - 我们大多数人都闻到了，因为它是海边气味的组成部分。但这远不止于此。海洋微生物每年约有3亿吨，大约有10％逃到大气中。这不仅会带回海上的日子记忆，而且DMS在空气中进行化学修饰，从而使云层在海洋上形成，从而影响天气和气候。而且，当下雨时，这些化合物又回到了地球，这是基本元素硫的全球循环循环。还有一件事。即使量很少，DM也吸引了不同的海洋动物 - 鱼，企鹅和小甲壳类动物都尽可能快地游泳，飞或划桨。原因是他们知道有DM的地方有食物。这是因为DMS是生物化学过程的副产品，当不同的微生物吞噬另一个含硫的分子时，它具有荒谬的长名 - 二甲基磺胺丙二二硫酸盐。该DMSP是由海洋中的微小浮游生物，海藻和少数居住在海边的陆地植物中的小浮游生物制成的。在UEA，我们发现了微生物如何制造DMS和Warwick，其他海洋微生物可以进一步改变这种气体的方式。我们使用分子生物学，基因克隆和DNA测序来鉴定整个微生物中的基因，使它们进行这些反应。对于这两个过程，我们都发现，一些非常出乎意料的生物可以制造或可以分解DM，并且可以完全不同且令人惊讶的方式来做到这一点。这些研究大多数是关于我们在实验室中生长的纯化菌株。这使我们能够识别基因及其个体功能，但是它并不告诉我们哪种是最重要的途径，哪些是自然环境中的主要参与者。这是因为在自然界中生活的大多数细菌从未被培养。幸运的是，一些最近的技术让我们研究这种“困难”微生物。穆雷尔教授发明的一个整洁的窍门是用一种与普通的底物相同的底物喂养自然的微生物种群，但从字面上看，这是更重的。因此，在我们的情况下，我们将使用DMS和DMSP的形式，其中碳原子的原子重量为13，而不是更常规的12。当微生物消化这样的重分子时，将重碳掺入其分子中，包括DNA。通过从光形式净化这种重的DNA并通过寻找基因中的签名序列，可以鉴定使用DMS或DMSP的微生物和真菌，并且可以推断出它们的机制。我们将对北诺福克盐沼泽的泥浆进行这些实验。这些是草spartina的所在地，这是制造DMSP的少数土地植物之一。这种植物也很重要，因为它已经通过人类的手遍布世界各地，现在在世界各地的许多海岸上都是严重的害虫，杀死了许多本地物种。毫不奇怪，Spartina根部周围有很多DMSP，这些DMSP与细菌和真菌一起食用或制造DMS。因此，我们将对这些微生物进行普查，其中一些微生物可能是科学的新知识。我们的发现应与DMS和DMSP的其他热点有关，例如珊瑚和海洋中浮游生物的大量盛开。尽管很小，但微生物的数量却意味着它们比我们大多数人意识到的要影响更多。鉴于DMS气体的环境后果，重要的是要知道影响其生产和破坏的细菌和真菌类型，以及涉及哪些潜在途径的哪种。这可能有助于我们建模环境变化（例如气候变化）如何改变这些过程的平衡。