...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Applied Microbiology >Syntrophic Propionate Oxidation via Butyrate: a Novel Window of Opportunity under Methanogenic Conditions
【24h】

Syntrophic Propionate Oxidation via Butyrate: a Novel Window of Opportunity under Methanogenic Conditions

机译：通过丁酸的共生丙酸氧化：产甲烷条件下的新型机会窗口

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Gan and colleagues (1) recently observed that upon the application of [~(13)C]propionate to anoxic paddy soil, label was concurrently incorporated in Smithella spp. and Syntrophomonas spp. Smithella spp. utilize propionate in a nonrandomizing pathway in which propionate is first dismutated to acetate and butyrate before being degraded via -oxidation (2, 3), while Syntrophomonadaceae are known butyrate degraders (4). This led the authors to raise the possibility of a trophic interaction between propionate- and butyrate-oxidizing syntrophs in the degradation of propionate in methanogenic ecosystems: when cultivated on propionate, Smithella propionica indeed produces (small amounts of) butyrate (2, 3).What the authors did not discuss though are the intriguing thermodynamic and energetic consequences of the Smithella pathway, consequences that may be of practical importance as propionate degradation is often a critical step in methanogenic bioreactors (5, 6). In the classical propionate degradation route, 3 mol of hydrogen (or formate) is produced per mol of substrate degraded (7, 8); for the alternative route via the Smithella pathway, the analogous ratio is 1. Consequently the windows of opportunity of the two pathways are different: there is a significant range of conditions under which propionate oxidation via the Smithella route is exergonic, whereas the classical pathway would be endergonic (Fig. 1A). Figure 1B illustrates this for the prevalent concentrations in the experiments of Gan and colleagues (1), where propionate and acetate are in the range of 10 mM and 1 mM, respectively. Unfortunately the authors did not provide data for H_(2). However, there is an intriguing report on propionate degradation in the literature that provides such data. Krylova and Conrad (9) reported apparently endergonic propionate oxidation in a methanogenic paddy soil, which they explained by assuming that propionate was degraded within microbial aggregates in which syntrophic propionate degraders were shielded from thermodynamically unfavorable H_(2) by methanogenic bacteria consuming H_(2). Figure 1C offers an alternative explanation and illustrates that propionate degradation via the Smithella pathway would be exergonic in this soil. This line of thinking has potential biotechnological applications, as the low thermodynamic sensitivity toward H_(2) of the Smithella pathway may lead to strategies to improve the precarious stability of propionate degradation in methanogenic waste treatment systems. Whether butyrate will be an important extracellular intermediate in such strategies remains to be seen.
机译：Gan及其同事（1）最近观察到，在将[〜（13）C]丙酸酯施用于缺氧水稻土后，Smithella spp中同时掺入了标签。和Syntrophomonas spp。 Smithella spp。在非随机途径中利用丙酸酯，其中丙酸酯先被歧化为乙酸酯和丁酸酯，然后再通过氧化被降解（2、3），而风湿单胞菌科则是已知的丁酸酯降解剂（4）。这导致作者提出了在产甲烷生态系统中丙酸酯和丁酸酯氧化的同养菌在丙酸酯降解中进行营养相互作用的可能性：在丙酸酯上种植时，丙酸史密氏菌确实产生（少量）丁酸酯（2、3）。尽管作者没有讨论的是史密斯拉途径的有趣的热力学和能量学结果，但由于丙酸酯降解通常是产甲烷生物反应器中的关键步骤，因此可能具有实际意义的结果（5、6）。在经典的丙酸酯降解途径中，每摩尔降解的底物会产生3摩尔的氢（或甲酸盐）（7、8）。对于通过史密斯拉途径的替代途径，类似比率为1。因此，这两种途径的机会窗口是不同的：在很大的条件下，通过史密斯拉途径的丙酸氧化是能运动的，而经典途径会呈阴性（图1A）。图1B说明了Gan和同事（1）实验中的普遍浓度，其中丙酸盐和乙酸盐的范围分别为10 mM和1 mM。不幸的是，作者没有提供H_（2）的数据。但是，在提供此类数据的文献中，有关于丙酸盐降解的有趣报道。 Krylova和Conrad（9）报道了在产甲烷的稻田土壤中明显的丙二酸丙二酸氧化，他们通过假设丙酸在微生物聚集体中被降解而解释，其中营养性丙酸降解物被热源不利于H_（2）的产甲烷细菌从热力学不利的H_（2）屏蔽。 ）。图1C提供了另一种解释，并说明了通过Smithella途径的丙酸酯降解将在该土壤中发挥作用。这种思路具有潜在的生物技术应用，因为对史密斯拉途径的H_（2）的低热力学敏感性可能会导致提高产甲烷废物处理系统中丙酸酯降解的不稳定稳定性的策略。丁酸酯在这种策略中是否将是重要的细胞外中间体尚待观察。

著录项

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