An ecophysiological analysis of marine facultatively lithotrophic bacteria

Drs。King和Tolli将分析Damariscotta河和缅因湾的近岸到近海样带以及近岸地点附近的潮间带沉积物中兼性养石菌和混合养石菌（FL/M）群落的意义、结构和功能。研究人员认为，FL/M群落在异养碳代谢以及一氧化碳（CO）、氢和其他还原性无机底物的动力学中发挥着重要而鲜为人知的作用。这些研究人员将利用他们最近开发的IA型和IC型细菌核酮糖-1,5-二磷酸羧化酶/加氧酶（rbcL）和CO脱氢酶（coxL）的大亚基基因的分子工具研究FL/M，并将首次应用于海洋系统的分析。CoxL将提供一些混合营养体和兼性养石生物的分布和多样性的见解；rbcL将提供关于兼性和专性养石生物的见解。最近对各种养石细菌rbcL序列和来自环境DNA的rbcL序列的分析表明，它们可以使用系统发育工具来区分兼性和专性养石细菌，从而使pi能够回答以前无法解决的关于养石群落结构的问题。此外，这些研究人员将确定FL/M群落的结构和多样性与微生物丰度、细胞呼吸活性（ETS活性）以及CO、氢、铵和硫代硫酸盐转化之间存在什么关系（如果有的话）。该研究的更广泛影响将来自于研究者在海洋生物地球化学、特定海洋微生物群体的生理学和生态学以及分子微生物生态学方面培养博士后研究助理、博士生和本科生的努力。此外，它们将有助于更好地了解缅因湾及其近岸生态系统，这两者在生态和经济上都具有区域尺度的重要性。

Drs. King and Tolli will analyze the significance, structure and function of bacterial facultative lithotroph and mixotroph (FL/M) communities along a near-shore to offshore transect in the water column of the marine Damariscotta River and the Gulf of Maine, and in intertidal sediments proximate to a near-shore sites. The investigators suggest that FL/M communities play important and poorly appreciated roles in heterotrophic carbon metabolism, as well as in the dynamics of carbon monoxide (CO), hydrogen and other reduced inorganic substrates. These researchers will investigate FL/M using molecular tools for the large sub-unit genes of form IA and IC bacterial ribulose-1,5-bisphosphate carboxylase/ oxygenase (rbcL), and CO dehydrogenase (coxL) that they have recently developed, and that they will apply for assays of marine systems for the first time. CoxL will provide insights regarding the distribution and diversity of some mixotrophs and facultative lithotrophs; rbcL will provide insights regarding both facultative and obligate lithotrophs. Recent analyses of various lithotrophic bacterial rbcL sequences and rbcL sequences from environmental DNA indicate that they can use phylogenetic tools to distinguish between facultative and obligate lithotrophs, thus allowing the PIs to answer questions about lithotrophic community structure that could not be addressed previously. In addition, these researchers will determine what relationships exist, if any, between the structure and diversity of FL/M communities and microbial abundance, cellular respiratory activity (ETS activity), and transformations of CO, hydrogen, ammonium and thiosulfate. The broader impacts of the proposed study will be derived from the investigator's efforts to train a postdoctoral research associate, Ph.D. student and undergraduate students in aspects of marine biogeochemistry, the physiology and ecology of specific groups of marine microbes and in molecular microbial ecology. In addition, they will contribute to a greater understanding of the Gulf of Maine and its near-shore ecosystems, both of which are ecologically and economically important a regional scales.