Role of Bacteria in Detrital Marine Foodwebs: Mechanisms inBacteria-Organic Matter Interactions

建议继续研究异养浮游细菌利用海洋中颗粒有机物（POM）和溶解有机物（DOM）的机制。该项目还在研究浮游上层和中上层地区进入细菌的有机物通量的大小和模式，以确定异养细菌如何影响海洋生物生产的垂直运输。本研究将重点研究细菌利用1-50 μ m小碎屑的机制和速率。该项目将使用实验室生产的、具有良好特征的“模型碎屑”，包括被杀死的浮游植物、微鞭毛虫和绿藻蓝藻。他将研究细菌在聚甲醛上的定植生长速率，并将研究细菌将聚甲醛水解成可利用DOM的酶机制；确定细菌细胞大小、生长速度和有机物水解模式的变化，这是POM附着或释放的结果。PI询问一个定植的粒子是否会成为DOM和细菌的点源（“婴儿机器”）。一个假设将被验证，即牢固附着于聚甲醛是细菌的一种生存/扩散策略；它们通过后生动物的肠道存活下来，并在粪便颗粒中茁壮成长。在现场工作中使用统一ı14C！标记碎屑，PI将测量各种大小范围的碎屑的周转时间，生化成分和来源。提出的研究将有助于在生态系统背景下建立细菌-有机物相互作用的机制框架。这一知识对于阐明浮游细菌在海洋有机物通量中的作用应该是有价值的。

Research is proposed to continue the study of the mechanisms whereby heterotrophic bacterioplankton utilize particulate organic matter (POM) and dissolved organic matter (DOM) in the sea. The PI is also studying the magnitude and patterns of organic matter flux into bacteria in both the epipelagic and the mesopelagic zones to determine how heterotrophic bacteria may influence the vertical transport of biogenic production in the sea. The research will focus on studying the mechanisms and rates of bacterial utilization of small detritus (1-50 um). The PI will use laboratory produced and well-characterized "model detritus" consisting of killed phytoplankton, microflagellates, and chroococoid cyanobacteria. He will study colonization growth rates of bacteria on POM and will examine enzymic mechanisms whereby bacteria hydrolyze POM into utilizable DOM; determine shifts in bacterial cell-size, growth rate, and modes of organic matter hydrolysis as a consequence of attachment to, or release from, POM. The PI asks whether a colonized particle becomes a point-source of DOM as well as of bacteria ("baby-machine"). A hypothesis will be tested that firm attachment to POM is a survival/dispersal strategy of bacteria; they survive the passage through metazoan gut and thrive in the fecal pellets. In field work using uniformly ı14C! labeled detritus, the PI will measure the turnover times of detritus of a broad size range, biochemical composition, and origins. The research proposed will contribute towards developing a mechanistic framework for bacteria-organic matter interactions in an ecosytem context. This knowledge should be of value in elucidating the role of bacterioplankton in organic matter fluxes in the oceans.