Spent coffee grounds as a cheap and renewable feedstock for the immobilization of candida rugosa lipase (CRL)

Spent coffee grounds as a cheap and renewable feedstock for the immobilization of Candida Rugosa Lipase (CRL) Viviana Chiappini1*, Paolo Amadoro1, Anna Maria Girelli1 1Department of Chemistry, La Sapienza University, Rome, Italy *viviana.chiappini@uniroma1.it Enzyme immobilization is a vastly used tool to enhance the stability and the reusability of biocatalysts, allowing the development of greener chemical and industrial processes. One of the main factors that defines the success of the immobilization is the nature of the support. Considering that synthetized specific supports may be very expensive, the scientific attention has been focused on the development of cheaper supports with the proper characteristics for a good immobilization [1]. In this context, lignocellulosic waste materials, such as spent coffee grounds (SCG), represent a great opportunity considering their large availability, inexpensiveness, and chemical-physical properties (large surface area, high porosity, high rigidity, and presence of active functional groups). In particular, spent coffee grounds, thanks to their very variable pore size, possess a opened structures with high adsorption capacity, large surface area and great pore volume, to the point that they have been exploited for adsorbents production [2,3]. It is common knowledge that porous materials like SCG are especially useful in the immobilization of proteins, such as enzymes, compared to non-porous materials. Therefore, also considering the possibility to reuse a waste material which would contribute to environmental pollution if not properly disposed, using SCG as support appeared to be a good choice for the synthesis of an efficient biocatalyst. The aim of this study was to investigate the possibility to use SCG as a solid carrier for the immobilization of Candida Rugosa Lipase (CRL). With this purpose it was pretreated and digested to eliminate lignin and make the cellulose more available for binding reaction with the lipase. The materials were characterized by SEM, IR, and elemental analysis. Subsequentially two different kinds of lipase covalent immobilization methods were evaluated: (i) binding after periodate oxidation of the support and (ii) binding after activation of the support with glutaraldehyde (GLU). The optimal immobilization conditions were determinated for each method and the yield, efficiency and recovery of each one were compared. 1. [1] A.M. Girelli, M.L. Astolfi, F.R. Scuto, Chemosphere, 2020, 244, 125368. 2. [2] J. Roh, H.N. Umh, C.M. Yoo, S. Rengaraj, B. Lee, Y. Kim, Korean Journal of Chemical Engineering, 2012, 29, 903-907. 3. [3] A. V. Buntić, M.D. Pavlović, D.G. Antonović, S.S. Šiler-Marinković, S.I. Dimitrijević-Branković, Heliyon, 2016, 2, e00146.