Elucidating Mechanisms of Metal Sulfide-Enabled Growth of Anoxygenic Photosynthetic Bacteria Using Transcriptomic, Aqueous/Surface Chemical, and Electron Microscopic Tools

紫色细菌通过无氧光合作用将光能转化为化学能。紫色硫细菌（PSB）是紫色细菌的一个亚群，其氧化还原态硫的过程与光合生长相耦合。虽然PSB被认为是各种生态系统中硫循环的关键驱动因素（例如，但它们的代谢能力和灵活性尚未完全了解。研究小组最近的工作证明了使用固相过渡金属硫化物（TMS）作为硫和电子供体的PSB菌株的强大自养生长。值得注意的是，这一发现揭示了PSB在直接从固相基质中清除电子方面的显着潜力，以及与TMS的密切联系，TMS自然发生在它们的小生境中，值得进一步研究。 因此，该小组将系统地研究PSB-TMS的相互作用和相关机制。这项工作可能对地球化学和生物电化学具有关键意义，通过为古代和现代金属-硫地球化学循环提供新的约束，建立细菌细胞外电子转移研究的新模型，并证明纳米颗粒光化学和微生物能量需求之间的潜在协同作用。在这项研究中要解决的主要研究问题是：（i）如果所有TMS阶段可能使光合细菌作为唯一的硫和电子供体的自养生长;（ii）什么分子机制参与了光合细菌-TMS相互作用。研究小组将使用转录组测序，透射电子显微镜结合先进的光谱和冷冻技术，以及各种水/表面化学分析工具来解决这些问题。为了最大限度地扩大其工作对社会的影响，它们将纳入协同外联和辅导活动。例如，他们将制作一系列动画短片（将在YouTube上播放），以传播这项工作的主要成果。他们还将开发一个开放获取的环境纳米科学教程。这些外展活动的长期目标是为跨学科STEM研究建立一个强大的管道，并将多样化的学生群体培养成一支有能力的STEM劳动力。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Purple bacteria convert light energy into chemical energy through anoxygenic photosynthesis. Purple sulfur bacteria (PSB) are a sub-group of purple bacteria, coupling the oxidation of reduced sulfur species to phototrophic growth. While PSB are recognized as key drivers of the sulfur cycle in various ecosystems (e.g., meromictic lakes, inland seas, and marine basins), their metabolic capability and flexibility are not fully understood. The research team's recent work demonstrated robust autotrophic growth of PSB strains using solid-phase transition metal sulfide (TMS) as sulfur and electron donors. Significantly, this finding reveals PSB’s remarkable potential in scavenging electrons directly from solid-phase substrate and close ties with TMS, which naturally occur in their niches, meriting further investigations. As such, the team will examine the PSB-TMS interactions and relevant mechanisms systematically. This work may have key implications for geochemistry and bioelectrochemistry, through providing new constraints for ancient and modern metal-sulfur biogeochemical cycles, establishing new models for bacterial extracellular electron transfer research, and demonstrating the potential synergy between nanoparticle photochemistry and microbial energy demand. The main research questions to be addressed in this study are: (i) if all TMS phases may enable the autotrophic growth of PSB as sole sulfur and electron donors; and (ii) what molecular mechanisms are involved in the PSB-TMS interactions. The research team will use a combination of transcriptomic sequencing, transmission electron microscopy coupled with advanced spectroscopy and cryo-techniques, and various aqueous/surface chemical analytical tools to resolve these questions. To maximize the impact of their work on society, they will incorporate synergistic outreach and mentoring activities. For example, they will create a series of short animation videos (to be hosted on YouTube) to disseminate the main results of this work. They will also develop an open-access Environmental Nanoscience tutorial. The long-term goal for these outreach activities is to create a robust pipeline for cross-disciplinary STEM research and to train a diverse group of students into a competent STEM workforce.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.