• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Modes of hydrogen production in the photosynthetic bacterium, Rhodospirillum rubrum.
【24h】

Modes of hydrogen production in the photosynthetic bacterium, Rhodospirillum rubrum.

机译：在光合细菌红景天菌中产氢的方式。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Photosynthetic microorganisms are becoming a major agricultural venue for renewable energy production. A novel concept of photosynthetic co-cultivation was proposed for the functional integration of complementary light-absorption and metabolism in purple photosynthetic bacteria and unicellular green algae, for enhanced hydrogen production. It was shown that the purple bacterium Rhodospirillum rubrum and green alga Chlamydomonas reinhardtii can grow harmoniously in the same medium. Furthermore, the light intensity perceived was shown to influence the constituency, favoring green algae at increasing intensities, and vice versa. With higher light, significant algal-derived oxygen was found to inhibit photosynthesis in purple bacteria, which instead flourished aerobically. Hydrogen was not evolved on account of the oxygen produced by algal photosynthesis and from ammonia nutrients required for the algae. Ammonia repression of the bacterial nitrogenase/hydrogenase was circumvented through use of a mutant of R. rubrum with constitutive expression of nitrogenase. An algal mutant with a decreased light-harvesting antenna was found to be more amenable for co-cultivation, as a balanced constituency was obtainable at higher light intensities.;Additional experiments were performed to investigate the merit of a fed-batch technique for purple bacterial hydrogen production, whereby stationary phase cells are treated as non-growing industrial catalysts. Inoculated cultures evolved hydrogen during exponential growth and continued to evolve at high rates for 70 h after growth had ceased. Upon replenishment of the electron donor, succinate, cultures resumed hydrogen evolution without further growth. However, rates and yields were lower with successive succinate additions than those observed during the initial growth phase. Supplementation of cultures with varying amounts of growth medium, given with the succinate replenishment, partially restored the hydrogen production rate and yield, and caused a proportional increase in biomass. Thus, while growth is not required for hydrogen production, this work establishes the necessity for cell growth in order to maintain maximal rates, suggesting the industrial suitability of a semi-continuous culture strategy.;The oxygen self-repression of hydrogen production in green algae can be addressed by sulfur-deprivation; thus it was investigated what effect such sulfur-deprivation might have upon hydrogen-producing purple bacterial cultures. The removal of sulfur nutrients halted growth in R. rubrum, with reductant and energy redirected toward storage polymer formation (poly-beta-hydroxybutyrate (PHB) and polysaccharides), some accumulating extracellularly. Hydrogen production ceased altogether, and the nitrogenase enzyme was shown to exhibit a prompt decline in activity, protein levels, and mRNA transcripts. This shift from hydrogen to polymer production was shown to be reversible upon replenishment of sulfur nutrients, suggesting the design of a photobiological system for alternating the processes of H2 and PHB production.
机译：光合微生物正在成为可再生能源生产的主要农业场所。提出了一种光合作用的新概念，用于紫色光合作用细菌和单细胞绿藻中互补光吸收和新陈代谢的功能整合，以提高产氢量。结果表明，紫色细菌Rhodospirillum rubrum和绿藻莱茵衣藻Chlamydomonas reinhardtii可以在同一培养基中和谐生长。此外，已显示感知到的光强度会影响选区，在强度增加时偏爱绿藻，反之亦然。在较高的光照下，发现大量藻类衍生的氧气会抑制紫色细菌的光合作用，而紫色细菌却有氧地繁盛。由于藻类光合作用产生的氧气以及藻类所需的氨养分无法释放出氢气。通过使用具有组成型表达固氮酶的R. rubrum突变株，可避免细菌固氮酶/氢化酶的氨抑制。发现具有减少集光触角的藻类突变体更适合共培养，因为在较高的光强度下可以获得平衡的组成。;进行了另外的实验，以研究分批补料技术对紫色细菌的优点。产生氢气，从而将固定相电池视为不增长的工业催化剂。接种的培养物在指数生长过程中会释放出氢气，并在生长停止后持续70 h继续高速生长。补充电子给体琥珀酸酯后，培养物恢复了氢的释放而没有进一步的生长。但是，连续添加琥珀酸盐的速率和产量要低于初始生长期。在补充琥珀酸的情况下补充不同数量的生长培养基，可以部分恢复氢气的产生速度和产量，并导致生物量成比例增加。因此，尽管不需要生产氢气来生长，但这项工作确立了细胞生长的必要性，以维持最大速率，这表明了半连续培养策略的工业适用性。绿藻中氧气对氢气生产的自我抑制可以通过减少硫磺来解决；因此研究了这种脱硫对产氢紫色细菌培养物可能产生的影响。硫营养素的去除阻止了R. rubrum的生长，还原剂和能量重新定向到存储聚合物的形成（聚-β-羟基丁酸酯（PHB）和多糖），其中一些在细胞外积聚。完全停止了氢气的产生，并且显示了固氮酶的活性，蛋白质水平和mRNA转录物迅速下降。补充硫养分后，这种从氢到聚合物生产的转变被证明是可逆的，这表明设计用于交替生产H2和PHB的光生物系统。

著录项

  • 作者

    Melnicki, Matthew Ross.;

  • 作者单位

    University of California, Berkeley.;

  • 授予单位 University of California, Berkeley.;
  • 学科 Alternative Energy.;Chemistry Biochemistry.;Biology Plant Physiology.;Biology Microbiology.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 183 p.
  • 总页数 183
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号