Department of Agroenvironmental Sciences and Technologies, University of Bologna, Viale Fanin 42, Bologna, Italy.
J Biotechnol. 2011 Dec 20;156(4):309-16. doi: 10.1016/j.jbiotec.2011.08.014. Epub 2011 Aug 22.
Vanillin is one of the most important flavors in the food industry and there is great interest in its production through biotechnological processes starting from natural substrates such as ferulic acid. Among bacteria, recombinant Escherichia coli strains are the most efficient vanillin producers, whereas Pseudomonas spp. strains, although possessing a broader metabolic versatility, rapidly metabolize various phenolic compounds including vanillin. In order to develop a robust Pseudomonas strain that can produce vanillin in high yields and at high productivity, the vanillin dehydrogenase (vdh)-encoding gene of Pseudomonas fluorescens BF13 strain was inactivated via targeted mutagenesis. The results demonstrated that engineered derivatives of strain BF13 accumulate vanillin if inactivation of vdh is associated with concurrent expression of structural genes for feruloyl-CoA synthetase (fcs) and hydratase/aldolase (ech) from a low-copy plasmid. The conversion of ferulic acid to vanillin was enhanced by optimization of growth conditions, growth phase and parameters of the bioconversion process. The developed strain produced up to 8.41 mM vanillin, which is the highest final titer of vanillin produced by a Pseudomonas strain to date and opens new perspectives in the use of bacterial biocatalysts for biotechnological production of vanillin from agro-industrial wastes which contain ferulic acid.
香草醛是食品工业中最重要的香料之一，人们对利用生物技术从天然底物（如阿魏酸）生产香草醛非常感兴趣。在细菌中，重组大肠杆菌菌株是最有效的香草醛生产菌，而假单胞菌属菌株虽然具有更广泛的代谢多功能性，但会迅速代谢各种包括香草醛在内的酚类化合物。为了开发能够高产、高生产力地生产香草醛的健壮假单胞菌菌株，通过靶向诱变使荧光假单胞菌 BF13 菌株的香草醛脱氢酶（vdh）编码基因失活。结果表明，如果 vdh 的失活与来自低拷贝质粒的阿魏酰辅酶 A 合成酶（fcs）和水合酶/醛缩酶（ech）的结构基因的同时表达相关联，工程衍生菌株 BF13 会积累香草醛。通过优化生长条件、生长阶段和生物转化过程的参数，可提高阿魏酸转化为香草醛的效率。开发的菌株可生产高达 8.41mM 的香草醛，这是迄今为止假单胞菌菌株生产香草醛的最高终浓度，为利用含有阿魏酸的农业工业废物中的细菌生物催化剂进行生物技术生产香草醛开辟了新的前景。
