Vast Amounts of Sugars Discovered Underneath Seagrass Meadows in the Ocean

在海洋中的海草草地下面发现了大量的糖

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Lush meadows of the seagrass Posidonia oceanica in the Mediterranean. Scientists at the Max Planck Institute of Marine Microbiology predict that their findings are relevant for many marine environments with plants, including other seagrass species, mangroves, and saltmarshes. Credit: HYDRA Marine Sciences GmbH

地中海海草 POSIDONIA OCEANICA草地郁郁葱葱。马克斯普朗克海洋微生物学研究所的科学家预测，他们的发现与许多有植物的海洋环境有关，包括其他海草物种、红树林和盐沼。图片来源：HYDRA Marine Sciences GmbH

Sweet Spots in the Sea: Mountains of Sugar Under Seagrass Meadows

Seagrass beds are underwater oases. Now scientists have discovered vast amounts of sugars underneath seagrass meadows. This sheds new light on how plants store carbon in the ocean.

海中的甜点：海草草地下的糖山

海草床是水下绿洲。现在，科学家们在海草草地下面发现了大量的糖。这为植物如何在海洋中储存碳提供了新的思路。

Seagrasses form lush green meadows in many coastal areas around the world. These marine plants are one of the most efficient global carbon sinks on the planet: One square kilometer of seagrass stores almost twice as much carbon as forests on land, and 35 times as fast. Now scientists from the Max Planck Institute for Marine Microbiology in Bremen, Germany, have discovered that seagrasses release massive amounts of sugar into their soils, the so-called rhizosphere. Sugar concentrations underneath the seagrass were at least 80 times greater than previously measured in marine environments.

海草在世界各地的许多沿海地区形成了郁郁葱葱的绿色草地。这些海洋植物是地球上最有效的全球碳汇之一：一平方公里的海草储存的碳几乎是陆地森林的两倍，速度是陆地森林的 35 倍。如今，来自德国不来梅的马克斯普朗克海洋微生物研究所的科学家们发现，海草会将大量的糖分释放到海草的土壤中，即所谓的根际。海草下的糖浓度至少比之前在海洋环境中测量的高 80 倍。

“To put this into perspective: We estimate that worldwide there are between 0.6 and 1.3 million tons of sugar, mainly in the form of sucrose, in the seagrass rhizosphere,” explains Manuel Liebeke, head of the Research Group Metabolic Interactions at the Max Planck Institute for Marine Microbiology. “That is roughly comparable to the amount of sugar in 32 billion cans of coke!”

“从这个角度来看：我们估计全球有 0.6 到 130 万吨糖，主要以蔗糖的形式存在于海草根际，”马克斯普朗克海洋微生物研究所代谢相互作用研究小组负责人 Manuel Liebeke 解释说。“这大约相当于 320 亿罐可乐中的糖量！”

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Beautiful to look at, hard to sample: Measuring metabolites like sucrose and polyphenols in seawater is difficult. The scientists from the Max Planck Institute for Marine Microbiology in Bremen had to develop a special method to deal with the large amounts of salt in seawater that make measurements of metabolites so difficult. Credit: HYDRA Marine Sciences GmbH

外观精美，取样困难：测量海水中的蔗糖和多酚等代谢物很困难。不来梅马克斯普朗克海洋微生物学研究所的科学家们不得不开发一种特殊的方法来处理海水中的大量盐分，因为盐分使得代谢物的测量变得如此困难。图片来源：HYDRA Marine Sciences GmbH

Polyphenols keep microbes from eating the sugar

Microorganisms love sugar: It is easy to digest and full of energy. So why isn’t the sucrose consumed by the huge community of microbes in the seagrass rhizosphere? “We spent a long time trying to figure this out,” says first author Maggie Sogin, who led the research off the Italian island of Elba and at the Max Planck Institute for Marine Microbiology.

多酚可防止微生物吃糖

微生物爱糖：容易消化，且充满能量。那么，为什么海草根际中庞大的微生物群落没有消耗蔗糖呢？“我们花了很长时间试图弄清楚这一点，”第一作者 Maggie Sogin 说，他在意大利厄尔巴岛和马克斯普朗克海洋微生物学研究所领导了这项研究。
“What we realized is that seagrass, like many other plants, release phenolic compounds to their sediments. Red wine, coffee, and fruits are full of phenolics, and many people take them as health supplements. What is less well known is that phenolics are antimicrobials and inhibit the metabolism of most microorganisms. “In our experiments, we added phenolics isolated from seagrass to the microorganisms in the seagrass rhizosphere – and indeed, much less sucrose was consumed compared to when no phenolics were present.”

“我们意识到海草和许多其他植物一样，会将酚类化合物释放到沉积物中。红酒、咖啡、水果都富含酚类物质，很多人都把它们当作保健品。 鲜为人知的是，酚类物质是抗菌剂，会抑制大多数微生物的新陈代谢。“在我们的实验中，我们将从海草中分离出来的酚类物质添加到海草根际的微生物中；事实上，与不存在酚类物质时相比，消耗的蔗糖要少得多。”