Abstract

The enzymatic synthesis of alkyl ferulates is an important reaction in cosmetic and pharmaceutical chemistries, since it may allow to expand the biorefinery concept valorizing biomass wastes enriched in ferulic acid. However, robust biocatalysts for that purpose are scarce. Herein, we have immobilized the type A feruloyl esterase from Aspergillus niger (AnFaeA) as cross-linked enzyme aggregates, employing chitosan as co-feeder (ChCLEAs). High immobilization yields and relative activity recovery were attained in all assessed conditions (> 93%). Furthermore, we enhanced the thermal stability of the soluble enzyme 32-fold. AnFaeA-ChCLEAs were capable to quantitatively perform the solvent-free direct esterification of short- to medium-chain alkyl ferulates (C4-C12) in less than 24 h. By raising the operational temperature to 50 °C, AnFaeA-ChCLEAs transformed 350 mM ferulic acid into isopentyl ferulate with a space-time yield of 46.1 g of product × L^-1 × day^-1, 73-fold higher than previously reported. The overall sustainability of this alkyl ferulate production bioprocess is supported by the high total turnover number (TTN 7 × 10⁵) and the calculated green metrics (E factor = 30). Therefore, we herein present a robust, efficient, and versatile heterogeneous biocatalyst useful for the synthesis of a wide diversity of alkyl ferulates.

Key points

• CLEAs of feruloyl esterase A from A. niger using chitosan as co-feeder were obtained.

• Microenvironment of the biocatalysts allowed to obtain C1 to C18 alkyl ferulates.

• Biocatalyst at boundary conditions showed a high productivity of 46 g/L day.

中文翻译：

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黑曲霉A型阿魏酸酯酶的壳聚糖基CLEAs：阿魏酸烷基酯合成的高产生物催化剂

摘要

阿魏酸烷基酯的酶促合成在化妆品和药物化学中是重要的反应，因为它可以扩展生物精炼概念，从而使富含阿魏酸的生物质废物得到增值。然而，用于该目的的健壮生物催化剂稀少。在这里，我们已经固定了黑曲霉的A型阿魏酸酯酶（AnFaeA）作为交联酶的聚集体，采用壳聚糖作为辅助原料（ChCLEAs）。在所有评估的条件下（> 93％）都可以实现较高的固定化产率和相对活性的恢复。此外，我们将可溶性酶的热稳定性提高了32倍。AnFaeA-ChCLEAs能够在不到24小时内定量完成短链至中链烷基阿魏酸酯（C4-C12）的无溶剂直接酯化反应。通过将操作温度提高至50°C，AnFaeA-ChCLEAs将350 mM阿魏酸转化为阿魏酸异戊酯，时空产量为46.1 g产品×L ^-1 ×day ^-1，比以前报道的高73倍。高总周转数（TTN 7×10 ⁵）和计算出的绿色指标（E因子= 30）支持了该阿魏酸烷基酯生产生物工艺的总体可持续性。因此，我们在本文中提出了用于合成多种多样的烷基阿魏酸酯的稳健，有效和通用的异质生物催化剂。

关键点

•获得了使用壳聚糖作为辅助原料的黑曲霉阿魏酸酯酶A的CLEA。

•允许获得C1至C18烷基阿魏酸盐的生物催化剂的微环境。

•边界条件下的生物催化剂显示出46 g / L天的高生产率。