PDF(Pubmed)
Abstract：
The ability of marine bacteria to direct their movement in response to chemical gradients influences inter-species interactions, nutrient turnover, and ecosystem productivity. While many bacteria are chemotactic towards small metabolites, marine organic matter is predominantly composed of large molecules and polymers. Yet, the signalling role of these large molecules is largely unknown. Using in situ and laboratory-based chemotaxis assays, we show that marine bacteria are strongly attracted to the abundant algal polysaccharides laminarin and alginate. Unexpectedly, these polysaccharides elicited stronger chemoattraction than their oligo- and monosaccharide constituents. Furthermore, chemotaxis towards laminarin was strongly enhanced by dimethylsulfoniopropionate (DMSP), another ubiquitous algal-derived metabolite. Our results indicate that DMSP acts as a methyl donor for marine bacteria, increasing their gradient detection capacity and facilitating their access to polysaccharide patches. We demonstrate that marine bacteria are capable of strong chemotaxis towards large soluble polysaccharides and uncover a new ecological role for DMSP in enhancing this attraction. These navigation behaviours may contribute to the rapid turnover of polymers in the ocean, with important consequences for marine carbon cycling.
摘要：
海洋细菌响应化学梯度而引导其运动的能力会影响物种间的相互作用，养分周转，和生态系统生产力。虽然许多细菌对小代谢物具有趋化性，海洋有机物主要由大分子和聚合物组成。然而，这些大分子的信号作用在很大程度上是未知的。使用原位和基于实验室的趋化性测定，我们表明，海洋细菌强烈地被丰富的藻类多糖海带多糖和藻酸盐所吸引。出乎意料的是,这些多糖比它们的寡糖和单糖成分引起更强的化学吸引力。此外，二甲基磺丙酸酯（DMSP）强烈增强了对海带蛋白的趋化性，另一种无处不在的藻类代谢产物.我们的结果表明，DMSP作为海洋细菌的甲基供体，增加他们的梯度检测能力，并促进他们获得多糖补丁。我们证明了海洋细菌能够对大量可溶性多糖具有很强的趋化性，并揭示了DMSP在增强这种吸引力方面的新生态作用。这些导航行为可能有助于聚合物在海洋中的快速周转，对海洋碳循环有重要影响。
