ABSTRACT

Lignin obtained from renewable biomass is a potential feedstock for the synthesis of various value-added chemicals through efficient biocatalytic routes. The ligninolytic enzymes-assisted depolymerization of lignin to vanillin constitutes the most commercially attractive and promising approach in green chemistry as vanillin constitutes the second most prevalent flavoring agent. Thus, in the present work, immobilized laccase and versatile peroxidase, and further, a co-immobilized laccase and versatile peroxidase system on magnetic silica microspheres (MSMS) were developed to generate a robust biocatalytic system that mediates the depolymerization of lignin obtained from Casuarina equisetifolia biomass. The depolymerization of lignin by free and immobilized laccase showed a vanillin yield of 24.8% and 23%, respectively, at pH 4.0 in 6 h at 30°C against a vanillin yield of 20% and 21.7% with the free and immobilized versatile peroxidase, respectively, at pH 5.0°C and 50°C. Comparatively, the system with the co-immobilized laccase and versatile peroxidase exhibited a 1-fold and 1.2-fold higher vanillin yield than the free and immobilized laccase system, respectively. On comparing with the versatile peroxidase system, the co-immobilized biocatalytic system displayed 1.3-fold and 1.2-fold increased vanillin yield than the free and immobilized versatile peroxidase system, respectively, at a pH of 6.0 in 6 h at 30°C with an enzyme concentration of 1 U/ml. The reusability studies of the co-immobilized biocatalytic system exhibited that both the enzymes retained up to 40% of its activity till sixth cycle.

Implications: The waste biomass of Casuarina equisetifolia is widely available around the coastal regions of India which does not have any agricultural or industrial applications. The present work exploits the lignocellulosic content of the Casuarina biomass to extract the lignin, which provides a renewable alternative for the production of the commercially high-valued compound, vanillin. This work also integrates a co-immobilized biocatalytic process comprising of laccase and versatile peroxidase leading to an environmentally benign enzymatic process for the depolymerization of lignin to vanillin.

摘要

从可再生生物质中获得的木质素是通过有效的生物催化途径合成各种增值化学品的潜在原料。木质素分解酶辅助的木质素解聚为香草醛构成了绿色化学中最具商业吸引力和前景的方法，因为香草醛构成了第二大最普遍的调味剂。因此，在本工作中，开发了在磁性二氧化硅微球（MSMS）上固定化漆酶和多功能过氧化物酶的系统，并进一步开发了一种固定化漆酶和多功能过氧化物酶系统以产生强大的生物催化系统，该系统介导了木麻黄的木素解聚。生物质。游离和固定化的漆酶对木质素的解聚反应显示，在pH值为4.0的条件下，在30°C下6小时内，香草醛的收率分别为24.8％和23％，而游离和固定的通用过氧化物酶的香草醛收率为20％和21.7％，分别在pH 5.0°C和50°C下。相比之下，具有固定化漆酶和通用过氧化物酶的系统分别比游离和固定漆酶系统的香草醛收率高1倍和1.2倍。与多功能过氧化物酶体系相比，在30°C下6 h的pH值为6.0时，固定化的生物催化体系的香草醛收率分别比游离和固定化多功能过氧化物酶体系高1.3倍和1.2倍。酶浓度为1 U / ml。

含义：木麻黄的废生物质在印度的沿海地区广泛存在，没有任何农业或工业应用。本工作利用木麻黄生物质中的木质纤维素含量来提取木质素，木质素为生产商业上有价值的化合物香草醛提供了可再生的选择。这项工作还整合了由漆酶和通用过氧化物酶共同固定的生物催化过程，从而导致了木质素解聚为香兰素的对环境无害的酶促过程。