Collaborative Research: Biological controls on reactive oxygen species in the oligotrophic ocean

人们一直认为，光氧化的发色溶解有机物是超氧化物（O2-）和过氧化氢（H2 O2）的主要来源;然而，有迹象表明，生物来源可能发挥重要的，如果不是占主导地位，在这些活性氧（ROS）的生产中的作用。 由于这些活性氧的存在下，在开放的海洋可以影响铁，铜，锰的氧化还原循环，从而影响其生物利用度和H2 O2已被证明可以抑制生长的原绿球藻生态型的混合层，重要的是要了解生物控制O2-和H2 O2。 为此，科罗拉多矿业学院和哈佛大学的科学家将检验以下假设：（1）暗生物生产是H2 O2和O2-对贫营养表层沃茨的重要贡献;（2）生物生产和分解速率的时空变化有助于观察到的H2 O2浓度的变化;（3）贫营养沃茨中H_2O_2的生物产生是通过O_2-的形成进行的，并且由O_2-生成H_2O_2的产量取决于主要的汇反应（例如与金属）O2-;（4）NADH的活性（烟酰胺腺嘌呤二核苷酸）氧化酶，其来自遗传学和生态学上不同的细菌群，包括蓝细菌和异养生物，是海洋沃茨ROS的重要来源。 为了检验前三个假设，在贫营养沃茨的亚热带北太平洋进行了一系列的实地观测，以建立生物生产率的H2 O2和O2-，并评估其关系的光化学生产和H2 O2浓度在真光层。 此外，还将进行实验室研究，以检查在不同的O2-汇的存在下，从O2-的H2 O2的化学计量产量。对于假设4，将鉴定参与ROS产生的微生物的多样性，以及所涉及的蛋白质，这将使得能够解释说明生物活性对ROS产生的可变贡献的区域的群落水平转录组数据。主要提议者计划在科罗拉多科学专业发展会议上就地球化学循环的重要性发表演讲。 如果成功收到，她建议将此材料开发成一个为期一天的研讨会，并通过科罗拉多矿业学校教师提高计划提供。 科罗拉多矿业学院的一名博士后和一名研究生以及哈佛大学的一名博士后、一名研究生和一名本科生将作为该项目的一部分得到支助和培训。

It has been assumed that photo-oxidation of chromophoric dissolved organic matter is the primary source of superoxide (O2-) and hydrogen peroxide (H2O2); however, there are indications that biological sources may play a significant, if not dominant, role in the production of these reactive oxygen species (ROS). Because the presence of these ROS in the open ocean can affect the redox cycling of iron, copper, and manganese which thereby influencing their bioavailability and H2O2 has been shown to inhibit the growth of Prochlorococcus ecotypes in the mixed layer, it is important to understand the biological controls on O2- and H2O2. For this reason, scientists at the Colorado School of Mines and Harvard University will test the following hypotheses: (1) dark biological production is an important contribution of H2O2 and O2- to oligotrophic surface waters; (2) spatial and temporal variations in biological production and decomposition rates contribute to the observed variability in H2O2 concentrations; (3) biological production of H2O2 in oligotrophic waters proceeds via formation of O2-, and the yield of H2O2 from O2- is variable depending on the major sink reactions (e.g. with metals) of O2-; and (4) activities of NADH (nicotinamide adenine dinucleotide) oxidase enzymes from a phylogenetically and ecologically diverse group of bacteria, including cyanobacteria and heterotrophs, are significant sources of ROS to marine waters. To test the first three hypotheses, a series of field observations in oligotrophic waters of the subtropical North Pacific will be carried out to establish biological production rates of H2O2 and O2- and assess their relationship to photochemical production and H2O2 concentrations in the euphotic zone. In addition, laboratory studies will also be conducted to examine the stoichiometric yield of H2O2 from O2- in the presence of different O2- sinks. For hypothesis 4, the diversity of microorganisms involved in ROS production will be identified, as well as the proteins involved which will enable the interpretation of community-level transcriptomic data for regions illustrating variable contributions of biological activity to ROS production.As regards broader impacts, the lead proponent plans to present a lecture at the Colorado Science Conference for Professional Development on the importance of biogeochemical cycles. If successfully received, she proposes to develop this material into a one day workshop and offer it via the Colorado School of Mines Teacher Enhancement Program. One postdoc and one graduate student from the Colorado School of Mines and one postdoc, one graduate student, and one undergraduate student from Harvard University would be supported and trained as part of this project.