古菌作为生命的第三种形式，是一类极其重要的微生物资源。极端嗜盐古菌-地中海富盐菌能以较低的生产成本，高效合成生物可降解材料PHBV(聚羟基丁酸羟基戊酸酯)，它由3HB和3HV两种单体组成，其中3HV含量约为10 mol%。本项目拟以地中海富盐菌为研究对象，针对该菌合成的PHA存在单体种类和比例单一这一问题展开深入系统的研究。拟采用发酵工程、代谢工程和代谢流分析的技术手段，通过量化PHA的单体供应，实现该菌智能合成单体种类[3HB，3HV和4HB（4-羟基丁酸）]和单体比例可控的、材料性能优良的新型短链PHA (scl-PHA)，并对它们在组织工程领域的高附加值应用进行初步研究。此外，综合运用多种分子生物学方法和检测手段，在该菌中激活或重建PHA重要前体4HB的新型合成途径。最终，本研究不仅将实现新型scl-PHA在古菌中的低成本合成，而且会拓宽我们对极端古菌生理代谢多样性及功能的认知。

Archaea, as the third domain of life, is a very valuable microbial resource. Haloferax mediterranei can effectively produce a biodegradable material-PHBV [poly(3-hydroxybutyrate-co-3-hydroxyvalerate)] with low production cost.PHBV is composed of two monomers, 3HB and 3HV, and the 3HV molar ratio of PHBV from H. mediterranei is about 10 mol%. This project will focus on solving the question that the monomer variety and content of PHA from H. mediterranei is fixed. We aim to synthesize scl-PHA (short-chain-length PHA) with controllable monomers (3HB, 3HV and 4HB) by H. mediterranei to gain excellent materials via fermentation and metabolic engineering.The metabolic fluxes of monomer supplying for PHA synthesis will be quantified to achieve this aim. The material properties of all the novle scl-PHA will be characterized in detail, and scl-PHA preliminary high-value application in the tissue engineering area will be carried out.The unique and novel biosynthetic pathway of 4HB will be activited or reconstructed in H. mediterranei using multiple molecular biology-based methods. This project will not only realize the biosynthesis of novel scl-PHA with low cost by archaea, but also will enrich our knowledge about the diversity and functions of physiology and metabolism in extreme archaea.