Biocatalysis in the pharmaceutical industry: beyond sustainability, towards efficiency

Introduction

The concept of sustainability undoubtedly occupies a prominent position in the vast scientific area, demonstrated by the impressive number of scientific papers that mention this topic in 2024 (24212 vs 4118 in 2014, source: Web of Science). Since the late 90s, the 12 guiding principles coined by Anastas and Warner have been pointing the road towards a more acceptable way to design manufacturing processes in any chemical field (1).
Whereas the optimum relies in preventing waste generation and maximizing the atom economy concept coined by Barry Trost (2), the use of catalyst moves towards this direction, demonstrated by the high number of scientific works done by the community over the year. Accordingly, it is not surprising that, from the vast realm of catalyst toolbox available to the (bio)chemist, the use of enzyme as powerful tools for exploiting the desired chemical reactions occupies a privileged position.
The unique combination of complex machines designed by Nature with the recent improvement driven by the direct evolution to “educate” enzymes to perform reaction not in their scope fosters the field to unprecedent level. Moreover, with the impressive improvement of the biological tools to engineer the enzyme allowed the consistent reduction of the random-mutation protocols and the relevant cost for the consumables needed to perform the design experiments. As a reference, today the price for plasmid production for research purposes goes lower than 100 USD (for 4 ug) and needs less than 1 week to have it ready in hand. With regards to timeframes for mutation screening, a single aminoacid random mutation screening on shake flask can be completed in less than 2 weeks and the recent application of artificial intelligence platforms promises to consistently decrease the number of experiments required to reach the desired target (3). There is vast literature about the topic that interested readers can access, such as the joint Academic and Industrial review coordinated by Prof. Bornscheuer (4). However, despite the massive improvements observed in these years in the field, the application of enzymes as catalyst for the manufacturing of goods of industrial relevance is still not heavily applied. Despite few notable examples, such as the application of PenG acylase to produce 6-aminopenicillanic acid (6-APA) and of invertase to produce syrup at tons scale, the use of enzyme at production scale remains underused due to their intrinsic problems. Among all, the limited reaction space (principally involving hydrolysis and oxidation), the high cost for development and manufacturing of the selected mutant and their stability in the reaction condition. While the scientific community is brilliantly demonstrating the ability to engineer enzymes to perform reactions that are outside their natural scope, enlarging the chemical space available, all these applications still are applied at lab scale, where the enzyme design and production are finalized to screen its ability to exploit the required reaction with the available substrates. On the other side, when the same enzyme has to move at industrial scale, “allosteric” parameters must be considered, such as their stability and catalytic activities at high substrate concentration or when immobilized to a solid support. Furthermore, their expression in the host must be robust and reproducible, in order to guarantee a sustainable and economically viable source of the desired enzyme. When coming to industrial scale, the enzymatic catalysis must compete with the existing classical chemical approaches, equalizing or surpassing their productivities.