NSF/CBET-BSF: Overcoming the Major Challenges to Algal Biohydrogen Production

氢气（H2）是一种很有前途的可再生燃料，也是一种有价值的工业气体，用于许多化学过程工业技术（例如化肥合成、石油炼制）。目前生产氢气的工业方法是天然气的蒸汽重整。这会产生二氧化碳，同时消耗甲烷，一种高价值的燃料。相比之下，光合微生物制氢利用阳光和丰富的资源（如废水或海水），避免与农业竞争粮食生产。这种技术方法在提高性能方面存在技术障碍。作为光合作用过程的一部分，分子氧，O2，形成了毒害产生氢的酶。本项目的目标是克服这些限制。将使用的策略是将藻类细胞中制造氢气的蛋白质机器与其他蛋白质连接起来，使氢气生产更有效。该项目的学习成果也将与K-12学生及其教师的外展计划分享，通过与ASU的全球可持续发展研究所合作，进行积极的学习实验室项目。两个主要的挑战限制了有效的生物H2生产：由O2的氢化酶的失活;和有限的电子流从光合机构的氢化酶。为了解决第一个挑战，假设是酶可以被附近的O2吸收机制所产生的局部微氧环境保护。将寻求几种在氢化酶附近减少O2的互补方法，包括使用嵌合蛋白，其中氢化酶与能够减少O2或活性氧物质的伴侣蛋白（例如葡萄糖氧化酶、黄二铁蛋白）连接。这些嵌合体将首先在体外进行测试，然后最有希望的嵌合体将在体内表达。快速的分子和光谱测试将用于确定工程菌株中光驱动制氢的限制。将利用几种遗传修饰来纠正电子流或H2生产活动中确定的限制。美国和以色列两个研究小组的互补专业知识将用于工程藻类细胞的创造，分析和优化。这两个小组将共同确定安排各种新组件的最佳方式，以实现持续的高水平生物制氢。

Hydrogen (H2) is a promising renewable fuel and a valuable commodity industrial gas used in many chemical process industry technologies (e.g. fertilizer synthesis, petroleum refining). The current industrial method to produce hydrogen is steam reformation of natural gas. This produces carbon dioxide while consuming methane, a high-value fuel. In contrast, hydrogen production by photosynthetic microbes makes use of sunlight and abundant resources (e.g. wastewater or seawater) and avoids competition with agriculture for food production. This technology approach has technical barriers to improved performance. As part of the photosynthesis process, molecular oxygen, O2, is formed that poisons the enzymes that produce the hydrogen. The goal of this project is to overcome these limitations. The strategy that will be used is to link the protein machines in the algal cells that make hydrogen to other proteins that could make hydrogen production more efficient. The learnings of this project will also be shared with an outreach program to K-12 students and their teachers for an active learning laboratory project by working with ASU's Global Institute of Sustainability.For industrial competitiveness, algal hydrogen production must be increased by at least 5-fold. Two major challenges limit efficient biological H2 production: inactivation of the hydrogenase enzyme by O2; and limited electron flow from the photosynthetic apparatus to the hydrogenase. To address the first challenge, the hypothesis is that the enzyme can be protected by local microoxic environments created by nearby O2 uptake mechanisms. Several complementary ways to reduce O2 at the vicinity of the hydrogenase will be pursued including use of chimeric proteins in which the hydrogenase is joined with a partner protein capable of reducing O2 or reactive oxygen species (e.g. glucose oxidase, flavodiiron protein). These chimeras will first be tested in vitro and then the most promising ones will be expressed in vivo. Rapid molecular and spectroscopic tests will be used to identify limitations to light-driven hydrogen production in the engineered strains. Several genetic modifications will be utilized to rectify identified limitations in electron flow or H2 production activity. Complementary sets of expertise in the two research groups in the US and Israel will be put to use in the creation, analysis, and optimization of the engineered algal cells. Together the two groups will determine the optimal way to arrange the various new components to make sustained high-level bio-hydrogen production a reality.