Collaborative Research: MIP: Bacterial Interactions and Processes that Regulate Biodiversity on Marine Organic Particles

海水中细菌的丰度和多样性在毫米尺度上有所不同，富含有机物的颗粒代表了微生物活动的“热点”。值得注意的是，附着在颗粒上的细菌在基因上与周围水中的细菌不同。定植在颗粒上的细菌利用物种特有的酶，以不同的速率分解有机成分。由于海洋下沉颗粒是影响全球碳通量的主要机制，因此细菌对海洋颗粒的代谢活动是生物地球化学循环的重要因素。然而，关于调节海洋颗粒上和周围微生物多样性的变量，人们知之甚少。本研究将探讨海洋微生物定殖颗粒之间的微尺度多样性和相互作用的控制机制。一个特别的焦点将是微生物的竞争，以及远洋细菌种群结构受到抗生素生产影响的可能性。实验将在分子、单个细菌细胞、联合体和群落水平上量化细菌拮抗相互作用的影响。模型粒子的定殖微生物自然组合将测量响应荧光标记的拮抗菌株。在接近拮抗细菌的敏感菌株的生长和呼吸将被测量，以量化单细胞水平上的相互作用。拮抗细菌产生的分子将被鉴定并测试它们对单个菌株和自然细菌联合体的粒子定植的影响。这是第一次深入研究细胞-细胞拮抗相互作用作为微观尺度因素参与构建海洋微生物群落。对悬浮颗粒上微生物多样性的认识将会进一步加深，对表面定植的相互作用和特定适应将会有更好的了解。这一努力将进一步融合海洋细菌化学生态学、微生物多样性和生物地球化学循环之间的联系。本科生和研究生将在化学生态学和分子微生物生态学方面进行交叉训练，未来的教师将在为期一年的实习中学习分子和微生物的技术和概念。

Bacterial abundance and diversity in ocean waters varies at the millimeter scale, and organic-rich particles represent "hot spots" for microbial activity. Remarkably, the bacteria found attached to particles are genetically distinct from those in the surrounding water. Bacteria that colonize particles employ species-specific enzymes that breakdown the organic content at different rates. Since sinking particles in the ocean represent a major mechanism influencing global carbon flux, bacterial metabolic activity on marine particles is an important factor in biogeochemical cycling. However, little is known regarding the variables that regulate microbial diversity on and around marine particles. This study will investigate mechanisms controlling micro-scale diversity and interactions among marine microorganisms colonizing particles. A specific focus will be microbial competition, and the possibility that pelagic bacterial population structures are influenced by the production of antibiotics. Experiments will be conducted to quantify the effects of bacterial antagonistic interactions at the molecular, single-bacteria cell, consortia, and community levels. The colonization of model particles by microbial natural assemblages will be measured in response to fluorescence-tagged antagonistic strains. Growth and respiration of sensitive strains in close proximity to antagonistic bacteria will be measured to quantify interactions at the single-cell level. Molecules produced by antagonistic bacteria will be identified and tested for their effects on particle colonization by single strains and natural consortia of bacteria. This is the first, in depth investigation to probe cell-cell antagonistic interactions as a micro-scale factor involved in structuring marine microbial communities. Knowledge of microbial diversity on suspended particles will be advanced, and the interactions and specific adaptations involved in surface colonization will be better understood. This endeavor will further fuse connections between marine bacterial chemical ecology, microbial diversity, and biogeochemical cycling. Undergraduate and graduate students will be cross-trained in chemical ecology and molecular microbial ecology, and future teachers will learn molecular and microbiological techniques and concepts during one-year internships.