Helmholtz Centre for Environmental Research, Department Environmental Microbiology, Leipzig, Germany.
Microb Cell Fact. 2010 Feb 25;9:13. doi: 10.1186/1475-2859-9-13.
Nowadays a growing demand for green chemicals and cleantech solutions is motivating the industry to strive for biobased building blocks. We have identified the tertiary carbon atom-containing 2-hydroxyisobutyric acid (2-HIBA) as an interesting building block for polymer synthesis. Starting from this carboxylic acid, practically all compounds possessing the isobutane structure are accessible by simple chemical conversions, e. g. the commodity methacrylic acid as well as isobutylene glycol and oxide. During recent years, biotechnological routes to 2-HIBA acid have been proposed and significant progress in elucidating the underlying biochemistry has been made. Besides biohydrolysis and biooxidation, now a bioisomerization reaction can be employed, converting the common metabolite 3-hydroxybutyric acid to 2-HIBA by a novel cobalamin-dependent CoA-carbonyl mutase. The latter reaction has recently been discovered in the course of elucidating the degradation pathway of the groundwater pollutant methyl tert-butyl ether (MTBE) in the new bacterial species Aquincola tertiaricarbonis. This discovery opens the ground for developing a completely biotechnological process for producing 2-HIBA. The mutase enzyme has to be active in a suitable biological system producing 3-hydroxybutyryl-CoA, which is the precursor of the well-known bacterial bioplastic polyhydroxybutyrate (PHB). This connection to the PHB metabolism is a great advantage as its underlying biochemistry and physiology is well understood and can easily be adopted towards producing 2-HIBA. This review highlights the potential of these discoveries for a large-scale 2-HIBA biosynthesis from renewable carbon, replacing conventional chemistry as synthesis route and petrochemicals as carbon source.
如今，对绿色化学品和清洁技术解决方案的需求不断增长，促使该行业努力寻求基于生物的构建块。我们已经确定含叔碳原子的 2-羟基异丁酸（2-HIBA）是合成聚合物的一种有趣的构建块。从这种羧酸出发，通过简单的化学转化，几乎可以获得所有具有异丁烷结构的化合物，例如商品甲基丙烯酸以及异丁烯二醇和氧化物。近年来，已经提出了生物技术生产 2-HIBA 酸的方法，并在阐明其基础生物化学方面取得了重大进展。除了生物水解和生物氧化外，现在可以采用生物异构化反应，通过新型钴胺素依赖性 CoA-羰基mutase 将常见代谢物 3-羟基丁酸转化为 2-HIBA。最近在阐明地下水污染物甲基叔丁基醚（MTBE）在新型细菌 Aquincola tertiaricarbonis 中的降解途径的过程中发现了后一种反应。这一发现为开发完全基于生物技术的 2-HIBA 生产工艺奠定了基础。mutase 酶必须在能够产生 3-羟丁酰-CoA 的合适生物系统中具有活性，3-羟丁酰-CoA 是众所周知的细菌生物塑料聚羟基丁酸酯（PHB）的前体。与 PHB 代谢的这种联系是一个巨大的优势，因为其基础生物化学和生理学已经得到很好的理解，可以很容易地应用于生产 2-HIBA。这篇综述强调了这些发现从可再生碳大规模生产 2-HIBA 的潜力，取代了传统化学作为合成路线和石化产品作为碳源。
