Cyclic Glucan Biosynthesis and Phospholipid Metabolism of Bradyrhizobium

慢生根瘤菌的环葡聚糖生物合成和磷脂代谢

• 批准号: 8803247
• 负责人: Karen Miller
• 金额: $ 21万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-07-15 至 1991-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8803247&HistoricalAwards=false
• 关键词: Cyclic; Glucan; Biosynthesis; Phospholipid; Metabolism

The long-term objective of the proposed research is to gain a further understanding of rhizobial bacteroid differentiation, a process essential for the development of effective nitrogen-fixing nodules on the roots of leguminous plants. Several lines of evidence have indicated that the cell- envelope composition of the Rhizobiaceae provides an essential function in this important microbial-plant symbiosis. The experimental plan will focus upon the characterization of the phospholipid and cyclic glucan oligosaccharide content of the cell-envelope of species of Bradyrhizobium. In addition, the phospholipid metabolism of the bradyrhizobia will be examined as well as the enzymic activities associated with the biosynthesis of the cyclic glucans of these bacteria. Experiments are based upon preliminary studies by the applicant that have indicated that the phospholipid metabolism of species of the Rhizobiaceae is intimately linked to the biosynthesis of the cyclic glucans of these bacteria. An important aspect of the proposed studies will be the examination of bradyrhizobial phospholipid and cyclic glucan content before, during, and after the induction of nitrogen-fixation in free-living microaerobic cultures.%%% The availability of water and a source of combined or fixed nitrogen represent the two most limiting factors in agricultural productivity. Because crop plants are not able to fix nitrogen, it must be provided in fixed form. This may be accomplished through the use of industrially synthesized nitrogen fertilizer, however, this synthetic process represents a very costly one in terms of the expenditure of fossil fuels. An alternative mechanism for acquiring fixed nitrogen has evolved in which certain plants are able to participate in a complex symbiotic relationship with nitrogen-fixing bacteria. The symbiotic relationship between leguminous plants and members of the family Rhizobiaceae represents not only an important source of globally fixed nitrogen, but also the most well-studied example of such symbiosis. The overall goal of this project is to gain further understanding of rhizobial bacteroid differentiation - a process essential for the successful development of nitrogen- fixing nodules on the roots of leguminous plants.***//

拟议的研究的长期目标是进一步了解根瘤菌细菌分化，这对于开发有效的豆科植物根部有效固氮结节至关重要。 几条证据表明，根茎科的细胞膜组成在这一重要的微生物植物共生中提供了重要功能。 实验计划将集中于dradyrhizobium物种细胞 - 层状磷脂和环状葡萄糖寡糖含量的表征。 此外，将检查勃雷氏菌的磷脂代谢，以及与这些细菌环状葡萄糖的生物合成有关的酶活性。 实验是基于申请人的初步研究，表明rhizobiaceae物种的磷脂代谢与这些细菌的环状葡萄糖的生物合成密切相关。 拟议的研究的一个重要方面是检查在自由活动的微培养物中氮含氮之前，之中和之后，在氮固定之前的研究之前，检查水的可用性以及合并或固定的两种最具限制性的农业生产率。 由于作物植物无法固定氮，因此必须以固定形式提供。 这可以通过使用工业合成的氮肥来实现，但是，就化石燃料的支出而言，这种合成过程代表了非常昂贵的过程。 获取固定氮的另一种机制已经进化，其中某些植物能够与固氮细菌一起参与复杂的共生关系。 豆科植物与家族根瘤科成员之间的共生关系不仅代表了全球固定氮的重要来源，而且还代表了这种共生的最深入的例子。 该项目的总体目的是进一步了解根瘤菌细菌分化 - 这对于成功发展豆科植物根部的氮结节至关重要。*** //