微生物合成茴香醛的研究进展

Research Progress in Synthesis of p-Anisaldehyde by Microorganisms

摘要: 八角是著名的香料和中药，在食品和医药有广泛应用。广西作为八角的主产区，八角及其提取物茴香油是目前主要的产品形式，在深加工方面仍然薄弱，附加值低。茴香油中的主要成分是反式茴脑，用生物合成法将反式茴脑转化生成的茴香醛可归为天然香料，对提高广西八角产业的附加值具有重要意义。目前已经发现多种真菌、细菌可以合成茴香醛，相关的酶主要包括反式茴脑加氧酶、芳基醇氧化酶、染料脱色过氧化物酶、依赖于Mn3+的蛋白酶。菌体合成茴香醛的代谢途径、酶的反应机制也有少量报道。总体来看，虽然已经发现多种能够合成茴香醛的微生物，但相关的酶、代谢途径研究仍然偏少，微生物合成茴香醛的产量、时空产率仍然偏低，国内关于这方面的分子生物学研究尤其缺乏。由于茴香醛对微生物本身具有毒性，与茴香醛合成相关的酶仍有很多未被发现，在利用微生物合成茴香醛时，一方面发掘更多的反式茴脑加氧酶，实现酶的高效表达及固定化；另一方面，建立原位产物分离工艺，探索高效的茴香醛生物合成与分离方法，这对八角产业水平的提升具有重要的理论及应用价值。

Abstract: As a well-known spice and traditional Chinese medicine, star anise has been used widely in food and drug industry. In Guangxi, the major production region, star anise and star anise oil are main product forms with little deep processing and low added value. The main constituent of star anise is trans-anethole, and p-anisaldehyde produced from trans-anethole by biosynthesis can be considered natural flavor, which is important for improvement of added values of Guangxi star anise industry. Several microorganisms have been found to produce p-anisaldehyde, and enzymes involved include trans-anethole oxygenase, aryl-alcohol oxidase, dye-decolorizing peroxidase, and Mn3+-dependent proteinase. The synthesis pathway of p-anisaldehyde in microorganisms and enzyme reaction mechanism is also investigated by some researchers. In general, investigations of enzymes and pathways involved in p-anisaldehyde production are still inadequate, although some p-anisaldehyde producing strains have been isolated. Production yield of p-anisaldehyde by microorganisms and space-time productivity are still low, and domestic molecular biology researches on this area are especially rare. In view of the toxicity of p-anisaldehyde on microbial cells and little amount of enzymes discovered, to synthesize p-anisaldehyde using microbial cells, on the one hand, researchers should explore more trans-anethole oxygenases and realize high level expression and immobilization. On the other hand, researchers should establish process of in situ product removal for cost-effective biosynthesis of p-anisaldehyde, which has important theoretical and practical value in increasing industry level of star anise.