Abstract

In the present work, different hydrolases were adsorbed onto polypropylene beads to investigate their activity both in short-esters and polyesters synthesis. The software MODDE® Pro 13 (Sartorius) was used to develop a full-factorial design of experiments (DoE) to analyse the thermostability and selectivity of the immobilized enzyme towards alcohols and acids with different chain lengths in short-esters synthesis reactions. The temperature optima of Candida antarctica lipase B (CaLB), Humicola insolens cutinase (HiC), and Thermobifida cellulosilytica cutinase 1 (Thc_Cut1) were 85 °C, 70 °C, and 50 °C. CaLB and HiC preferred long-chain alcohols and acids as substrate in contrast to Thc_Cut1, which was more active on short-chain monomers. Polymerization of different esters as building blocks was carried out to confirm the applicability of the obtained model on larger macromolecules. The selectivity of both CaLB and HiC was investigated and best results were obtained for dimethyl sebacate (DMSe), leading to polyesters with a Mw of 18 kDa and 6 kDa. For the polymerization of dimethyl adipate (DMA) with BDO and ODO, higher molecular masses were obtained when using CaLB onto polypropylene beads (CaLB_PP) as compared with CaLB immobilized on macroporous acrylic resin beads (i.e., Novozym 435). Namely, for BDO the Mn were 7500 and 4300 Da and for ODO 8100 and 5000 Da for CaLB_PP and for the commercial enzymes, respectively. Thc_Cut1 led to polymers with lower molecular masses, with Mn < 1 kDa. This enzyme showed a temperature optimum of 50 °C with 63% of DMA and BDO when compared to 54% and 27%, at 70 °C and at 85 °C, respectively.

Highlights

  • Plastic has succeeded to enter in each and every aspect of our lives, providing a cheap, lightweight, and inexpensive material having outstanding properties

  • In order to study their thermostability and selectivity in synthesis reactions, MODDE® Pro 13 (Sartorius) was adopted as software to develop a full-factorial design of experiment (DoE), in which enzyme transesterification activity to obtain flavor esters was investigated

  • Results showed that both Candida antarctica lipase B (CaLB) and Humicola insolens cutinase (HiC) expressed their selectivity towards long-chain alcohols and acids, while their optimum temperature were found at 85 ◦C and 70 ◦C, respectively

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Summary

Introduction

Plastic has succeeded to enter in each and every aspect of our lives, providing a cheap, lightweight, and inexpensive material having outstanding properties. The annual European production has been steady in the past decade, the global production is constantly increasing and reached 368 million tons in 2019 [5]. All these issues, in combination with the major problems that have emerged in the last 40 years, such as climate change, depletion of oil fields, and environmental pollution, highlight the importance of moving towards more sustainable, bio-based, and environmentally friendly processes across a wide range of different industries

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