Collaborative Research: Microbial Interactions with Marine Plastic Debris: Diversity, Function and Fate

塑料海洋废弃物是第二次世界大战后在消费品中广泛使用聚合物导致的海洋生态系统的最新介绍。目前，全球每年生产的塑料为2.45亿吨，相当于地球上70亿人每人生产35公斤塑料，相当于所有人类的生物量总和。漂流浮标和物理海洋学模型表明，表面颗粒在不到60天的时间内被动地从海岸线迁移到中央环流，说明人类产生的碎片如何迅速地影响到距离陆地1 000公里以上的原始环流内部。塑料碎片被认为是有害藻类物种和持久性有机污染物的传播媒介，并为微生物提供了在环境之间移动的基质，比大多数自然漂浮基质持续时间更长。尽管塑料产量增加，但自1985年以来，没有观察到塑料积累的显著趋势。物理剪切和光降解是塑料降解的已知机制，但也涉及微生物降解。采用靶向细菌和真核生物小亚基核糖体RNA基因序列的pyrotag扩增子测序的未发表数据，以及扫描电子显微镜（SEM）数据，与塑料碎片含有微生物（包括能够降解塑料的成员）的独特关联的观点一致。“塑料圈”一词描述了附着在海洋塑料垃圾上和周围的这种独特的微生物群落，与周围海水和天然基质（如大型藻类）中的微生物不同。本项目将：（1）通过扩增子测序和比较组学结合扫描电镜和共聚焦显微镜来研究塑料圈的微生物组成;（2）描述Plastisphere的功能，其采用不依赖于培养的环境DNA基因表达方法，以及基于培养的方法来询问环境克隆和微生物分离株降解烃的能力;以及（3）确定控制上层水体中塑料碎片命运的关键生物因素。塑料现在是最丰富的海洋废弃物形式。了解塑料如何影响脆弱的开放海洋环境中食物网的基础是本提案中将解决的首要问题，并为已被确定为高优先级研究领域的新兴研究课题提供基础。了解微生物如何与北大西洋亚热带环流和北太平洋亚热带环流（地球上最大的两个生物群落）中积累的塑料碎片相互作用，将为后续研究问题提供基础，例如：微生物生物膜是否为过滤器喂养的浮游动物提供营养？大量的塑料碎片是如何影响这些脆弱生物群落的健康的？是否可以配制出一种真正可生物降解的塑料，使其对贫营养环境的影响最小？ 随着人口的增长以及第二和第三世界的经济增长，不可避免地会有更多的塑料垃圾进入海洋，并聚集在环流等汇聚区。该项目的现场部分是围绕参与海洋教育协会的本科生的独立研究项目建立的。的SEA学期研究巡航在大西洋和太平洋。除了指导SEA学期的学生谁将收集样本，并帮助这个项目全年，该项目将从事教师和学生从加勒比地区谁是在格林纳达圣乔治大学学习。美国代表性不足的少数民族将通过伙伴关系教育计划（PEP）计划、WHOI少数民族奖学金计划和伍兹霍尔生物发现MBL REU网站计划得到指导。2010年，将通过专门的“海洋塑料考察”网站向公众和K-12教师和学生进行宣传，增加一个专门讨论微生物生态学和塑料海洋废弃物在公海海洋生态系统中的作用的部分。研究团队的所有成员将通过在船上的讲座和参与，为新开发的“海洋生物多样性和保护”本科课程做出贡献。

Plastic marine debris is a recent introduction to marine ecosystems resulting from the widespread use of polymers in consumer goods after World War II. The current global annual production of plastic is 245 million tonnes or 35 kg of plastic for each of the 7 billion humans on the planet, rivaling the combined biomass of all humans. Drifter buoys and physical oceanographic models demonstrate that surface particles passively migrate from the coastline to the central gyres in less than 60 days, illustrating how quickly human-generated debris can impact the pristine gyre interiors, more than 1000 km from land. Plastic debris has been implicated as a vector for transportation of harmful algal species and persistent organic pollutants, and provides a substrate for microbes that moves between environments and lasts much longer than most natural floating substrates. Despite increases in plastic production no significant trend in plastic accumulation has been observed since 1985. Physical shearing and photodegradation are known mechanisms of plastic degradation, but microbial degradation has also been implicated. Unpublished data employing pyrotag amplicon sequencing targeting bacterial and eukaryotic small subunit ribosomal RNA gene sequences, together with Scanning Electron Microscopy (SEM) data are consistent with the notion that plastic debris harbors a unique association of microbes including members capable of degrading plastic. The term "Plastisphere" describes this unique microbial community attached to and surrounding marine plastic debris and distinct from microbes in the surrounding seawater and on natural substrates such as macroalgae.This project will: (1) characterize diversity through amplicon sequencing and comparative -omics combined with SEM and confocal microscopy to investigate the microbial composition of the Plastisphere; (2) describe function of the Plastisphere taking a cultivation-independent environmental DNA gene expression approach, as well as a cultivation-based approach to interrogate environmental clones and microbial isolates for the ability to degrade hydrocarbons; and (3) determine key biological factors that control the fate of plastic debris in the upper water column.Intellectual Merit. Plastic is now the most abundant form of marine debris. Gaining an understanding of how plastic is affecting the very foundation of the food web in delicate open ocean environments is a first order question that will be addressed in this proposal and provides a base for an emerging research topic that has been identified as a high-priority research area. Understanding how microbes interact with plastic debris that accumulates in the North Atlantic Subtropical Gyre and North Pacific Subtropical Gyre (two of the largest biomes on Earth) will provide a foundation for follow-up research questions such as: Do microbial biofilms provide sustenance for filter feeding zooplankton?; how is the abundance of plastic debris affecting the health of these delicate biomes?; and can a truly biodegradable plastic be formulated that will have minimal impact on the oligotrophic environment? With a growing human population and second and third world economic growth, it is inevitable that more plastic debris will find its way into the ocean and collect in convergence zones such as the gyres.Broader Impacts. The field component of this project is built around independent research projects by undergraduate students participating in Sea Education Association?s SEA Semester research cruises in the Atlantic and Pacific oceans. In addition to mentoring SEA Semester students who will be collecting samples and helping with this project throughout the year, the project will engage faculty and students from the Caribbean region who are studying at St. Georges University in Grenada. Underrepresented minorities in the US will be mentored through the Partnership Education Program (PEP) program, the WHOI minority fellowship program, and the MBL REU Site program in Biological Discovery in Woods Hole. Outreach to the general public and K-12 teachers and students will be delivered through a dedicated website for the "Plastics at SEA expedition" in 2010 by adding a section that specifically addresses microbial ecology and the role of plastic marine debris in open ocean marine ecosystems. All members of the research team will contribute to a newly developed undergraduate curriculum in "Marine Biodiversity and Conservation" via lectures and participation aboard ship.