Microbial interactions on particulate organic matter: from community structure to function

对于海洋细菌来说，海洋是一片广阔的沙漠，其间点缀着富含有机碳的动物和藻类组织碎片的营养热点。海洋细菌定居并消耗这些热点，将它们转化为溶解的营养物质，并向大气中释放二氧化碳。这一过程对全球碳循环有着巨大的影响，但其动态和效率完全取决于在这些微观热点范围内展开的鲜为人知的生态过程。该研究旨在确定和量化这些微观尺度的生态过程，特别是关于营养热点海洋细菌物种之间的相互作用如何影响海洋中碳周转的动态和效率。为此，本项目将采用新技术培养生活在营养热点的海洋细菌，并测量它们的种间相互作用及其对生态系统功能的影响。该项目将直接培养2名本科生和1名博士。学生。该项目的研究结果将通过一系列播客传播给广大受众，重点关注微生物在微观尺度上的复杂生命如何影响生物地球化学循环。这些将由麻省理工学院的本科生和研究生开发。本研究的主要假设是，微生物相互作用频繁发生在营养热点地区，对有机质周转速度产生重大影响，从而影响全球碳循环。为了验证这一想法，由海洋环境中常见的生物聚合物组成的海洋模型粒子将被用作天然微生物群落的支架。这项技术将使研究人员能够以可控和定量的方式研究群落动态和功能。本工作将确定在颗粒附着群落中活跃的主要生态物种及其在颗粒消耗过程中的功能作用。这项研究还将确定群落中细菌之间的相互作用如何影响降解率和有机物转化为生物量、二氧化碳和其他形式的溶解碳扩散到水柱中的效率。

For marine bacteria the ocean is a vast desert punctuated by hotspots of nutrients originating from fragments of animal and algal tissue rich in organic carbon. Marine bacteria colonize and consume these hotspots, turning them into dissolved nutrients and releasing CO2 to the atmosphere. This process has tremendous implications for the global carbon cycle, but its dynamics and efficiency are fully determined by poorly understood ecological processes that unfold at the scale of those microscopic hotspots. The research aims to identify and quantify those micro-scale ecological processes, in particular with respect to how interactions between species of marine bacteria on nutrient hotspots impact the dynamics and efficiency of carbon turnover in the ocean. To this end, this project will use novel techniques to cultivate marine bacteria that live on nutrient hotspots and to measure their interspecies interactions as well as their effect on ecosystem function. This project will directly train two undergraduate students and one PhD. student. The findings of this project will be communicated to a broad audience via a series of podcasts focused on how the complex life of microbes at micro-scales impact biogeochemical cycles. These will be developed by undergraduate and graduate students at MIT.The main hypothesis behind this research is that microbial interactions, frequently occurring on nutrient hotspots, have a significant impact on the rate of organic matter turnover, thereby affecting the global carbon cycle. To test this idea, model marine particles composed of biopolymers frequently found in marine environments will be used as scaffolds for natural microbial communities. This technique will allow the researchers to study community dynamics and function in a controlled and quantitative fashion. This work will identify the main ecological species active in the particle-attached communities as well as their functional roles during particle consumption. The research will also determine how interactions between bacteria in the community impact the degradation rate and the efficiency with which organic matter is turned into biomass, CO2 and other forms of dissolved carbon that diffuse into the water column.