Patinios Constantinos, Lanza Lucrezia, Corino Inge, Franssen Maurice C R, Van der Oost John, Weusthuis Ruud A, Kengen Servé W M
Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University and Research, Wageningen, Netherlands.
Laboratory of Bioprocess Engineering, Department of Agrotechnology and Food Sciences, Wageningen University and Research, Wageningen, Netherlands.
Front Microbiol. 2020 Oct 29;11:579844. doi: 10.3389/fmicb.2020.579844. eCollection 2020.
Esters are important flavor and fragrance compounds that are present in many food and beverage products. Many of these esters are produced by yeasts and bacteria during fermentation. While ester production in yeasts through the alcohol acyl transferase reaction has been thoroughly investigated, ester production through alcoholysis has been completely neglected. Here, we further analyze the catalytic capacity of the yeast Eat1 enzyme and demonstrate that it also has alcoholysis and thiolysis activities. Eat1 can perform alcoholysis in an aqueous environment , accepting a wide range of alcohols (C2-C10) but only a small range of acyl donors (C2-C4). We show that alcoholysis occurs in several Crabtree negative yeast species but also in engineered strains that overexpress Eat1 homologs. The alcoholysis activity of Eat1 was also used to upgrade ethyl esters to butyl esters by overexpressing Eat1 in . Approximately 17 mM of butyl acetate and 0.3 mM of butyl butyrate could be produced following our approach. Remarkably, the alcoholysis activity is 445 times higher than the previously described alcohol acyl transferase activity. Thus, alcoholysis is likely to affect the ester generation, both quantitatively and qualitatively, in food and beverage production processes. Moreover, mastering the alcoholysis activity of Eat1 may give rise to the production of novel food and beverage products.
酯类是重要的风味和香料化合物，存在于许多食品和饮料产品中。其中许多酯类是酵母和细菌在发酵过程中产生的。虽然通过醇酰基转移酶反应在酵母中产生酯类已得到充分研究，但通过醇解产生酯类却完全被忽视了。在这里，我们进一步分析了酵母Eat1酶的催化能力，并证明它也具有醇解和硫解活性。Eat1可以在水性环境中进行醇解，接受多种醇类（C2 - C10），但只接受少量的酰基供体（C2 - C4）。我们表明，醇解发生在几种克勒勃屈利阴性酵母物种中，也发生在过表达Eat1同源物的工程菌株中。通过在[具体菌株]中过表达Eat1，Eat1的醇解活性还被用于将乙酯升级为丁酯。按照我们的方法，大约可以产生17 mM的乙酸丁酯和0.3 mM的丁酸丁酯。值得注意的是，醇解活性比先前描述的醇酰基转移酶活性高445倍。因此，醇解很可能在食品和饮料生产过程中对酯类的生成在数量和质量上都产生影响。此外，掌握Eat1的醇解活性可能会带来新型食品和饮料产品的生产。
