Biocomplexity:Coupled Biogeochemical Cycling of Sulfur and Carbon in Anoxgenic Acidic Sulfidic Thermal Springs (AASTS)in Relation to Microbial Composition of Phototrophic Mats

限制环境中的生命及其与生物地球化学循环和矿化的相互作用对于理解现代和古代生物地球化学循环以及生物工程系统中类似的相互作用至关重要。厌氧，酸性，硫化物，温泉（aast）代表了地球上最早的生物的潜在重要环境，而居住在其中的光养生物（如绿硫细菌）是地球上最早的光合作用者的极好候选者。如果类似aast的环境在地球早期更为广泛，那么嗜热绿硫细菌对全球碳和硫的生物地球化学循环的古意义可能是巨大的，对其他元素/金属循环和矿化的影响也可能非常重要。了解aast中的光养群落也可能对废物处理和能源生产具有实际意义。该孵化项目的长期目标是模拟(i)硫、碳和其他营养物质的耦合生物地球化学循环与（ii） aast中光养群落代谢活动之间的联系。工作假设是，光养群落的存在和生物多样性是这些环境中耦合地球化学循环的涌现特性。aast中碳和硫的循环以及其他环境参数（如pO2、pH、T）稳定了群落组成，进而影响下游微生物群落可利用的碳和硫化合物的分布。本孵化项目旨在建立aast的基本微生物学和生物地球化学特征，为两者相互作用的定量建模奠定基础。对aast的紧急特性，特别是微生物群落与非生物环境之间的非线性相互作用和反馈进行建模，需要对微生物多样性进行绝对估计，并对关键生命维持成分（例如硫和碳）的通量进行量化。为了实现这一目标，传统的微生物学和基于16S rrna的分子技术被用来表征菲律宾最近发现的两个由嗜热绿硫细菌居住的aast的微生物组成。同时，在相同的aast中开展了硫、碳和整体地球化学循环的实地研究，重点研究了硫和碳的形态特征，并利用分离物种稳定的S、C和H同位素组成和选择的生物标志物来研究这些组分在这些独特微生物栖息地中的循环。研究伴生热水中无机硫和碳的同位素组成将有助于评估这些微生物群落中S利用和C固定的大小和顺序。最后，将对aast中微生物分布和结构与S和C耦合循环的关系进行初步建模。初始模型将研究aast水柱中的物种通量、运输和转化，特别关注地球化学通量与微生物发生、组成和分布之间的相互作用。本项目旨在培养面向本科生、研究生、国际合作者和公众的跨学科科学研究和教育。重点包括在aast中开发基于网络的多层次生物复杂性虚拟学校，以及为菲律宾和美国合作者举办的同一主题研讨会。鉴于全球认识到出于基本和生物技术原因需要保护和了解独特的微生物系统，因此制定了在研究和教育方面建立强有力的国际伙伴关系的计划。

Life in restrictive environments and its interaction with biogeochemical cycling and mineralization are of paramount importance for understanding modern and ancient biogeochemical cycles, as well as similar interactions in bioengineered systems. Anaerobic, acidic, sulfidic, thermal springs (AASTS) represent potentially important settings for the earliest organisms on Earth, and the phototrophs inhabiting them (e.g., green sulfur bacteria) are excellent candidates for Earth's earliest photosynthesizers. If environments similar to AASTS were more widespread on the early Earth, the paleo-significance of thermophilic green sulfur bacteria for the global biogeochemical cycling of carbon and sulfur could be immense, and its implications to other element/metallic cycling and mineralization could also be very significant. Understanding phototrophic communities in AASTS could also have practical implications for waste treatment and energy production. The long-term goal of this incubation project is to model the linkage between (i) coupled biogeochemical cycling of sulfur, carbon and other nutrients and (ii) the metabolic activities of phototrophic communities in AASTS. The working hypothesis is that the existence and biodiversity of phototrophic communities are emergent properties of the coupled geochemical cycles in these environments. The cycling of carbon and sulfur in AASTS, along with other environmental parameters (e.g., pO2, pH, T), stabilizes the community composition, which in turn affects the distribution of carbon and sulfur compounds available to microbial communities downstream. This incubation project is specifically designed to establish the basic microbiological and biogeochemical characteristics of AASTS, and lay the foundation for quantitative modeling of the interactions between the two. Modeling of emergent properties of AASTS, specifically the non-linear interactions and feedback between the microbial community and the abiotic environment, requires absolute estimates of microbial diversity and quantification of fluxes of crucial life-sustaining components (e.g., sulfur and carbon). To accomplish this goal classical microbiological and 16S rRNA-based molecular techniques are being utilized to characterize the microbial composition of two recently discovered AASTS inhabited by thermophilic green sulfur bacteria in the Philippines. In parallel, field studies of sulfur, carbon and overall geochemical cycling in the same AASTS are being carried out, focusing on characterizing sulfur and carbon speciation, and using stable S, C and H isotope compositions of isolated species and select biomarkers to study the cycling of these components in these unique microbial habitats. Examining the isotope composition of inorganic sulfur and carbon species in the associated thermal waters will allow the assessment of the magnitude and sequence of S utilization and C fixation in these microbial communities. Finally, preliminary modeling of coupled S and C cycling in relation to the microbial distribution and structure in AASTS will be performed. The initial model will examine species fluxes, transport and transformation in the water column of AASTS, specifically focusing on the interaction between geochemical fluxes and microbial occurrence, composition and distribution. This project plans to foster interdisciplinary scientific research and education for undergraduates, graduate students, international collaborators and the public. Highlights include development of a web-based multi-level Virtual School on Biocomplexity in AASTS and workshops for the Philippine and US collaborators on the same topic. Given the global recognition of the need to preserve and understand unique microbial systems for fundamental and biotechnical reasons, plans are incorporated for strong international partnerships in research and education.