Based on the principles and metrics of green chemistry and sustainable development, biocatalysis is both a green and sustainable technology. This is largely a result of the spectacular advances in molecular biology and biotechnology achieved in the past two decades. Protein engineering has enabled the optimization of existing enzymes and the invention of entirely new biocatalytic reactions that were previously unknown in Nature. It is now eminently feasible to develop enzymatic transformations to fit predefined parameters, resulting in processes that are truly sustainable by design. This approach has successfully been applied, for example, in the industrial synthesis of active pharmaceutical ingredients. In addition to the use of protein engineering, other aspects of biocatalysis engineering, such as substrate, medium, and reactor engineering, can be utilized to improve the efficiency and cost-effectiveness and, hence, the sustainability of biocatalytic reactions. Furthermore, immobilization of an enzyme can improve its stability and enable its reuse multiple times, resulting in better performance and commercial viability. Consequently, biocatalysis is being widely applied in the production of pharmaceuticals and some commodity chemicals. Moreover, its broader application will be further stimulated in the future by the emerging biobased economy.

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Biocatalysis is an emerging area of technology, and to date few reports have documented the economics of such processes. As it is a relatively new technology, many processes do not immediately fulfill the economic requirements for commercial operation. Hence, early-stage economic assessment could be a powerful tool to guide research and development activities in order to achieve commercial potential. This study discusses the cost contribution of the biocatalyst in processes that use isolated enzymes, immobilized enzymes, or whole cells to catalyze reactions leading to the production of chemicals. A methodology for rapidly estimating the production cost of the biocatalyst is presented, and examples of how the cost of the biocatalyst is affected by different parameters are given. In particular, it is seen that the fermentation yield in terms of final achievable cell concentration and expression level as well as the production scale are crucial for decreasing the total cost contribution of the biocatalyst. Moreover, it is clear that, based on initial process performance, the potential to reduce production costs by several orders of magnitude is possible. Guideline minimum productivities for a feasible process are suggested for different types of processes and products, based on typical values of biocatalyst and product costs. Such guidelines are dependent on the format of the biocatalyst (whole-cell, soluble enzyme, immobilized enzyme), as well as product market size and value. For example commodity chemicals require productivities in the range 2000-10000 kg product/kg immobilized enzyme, while pharmaceutical products only require productivities around 50-100 kg product/kg immobilized enzyme.

The aerobic oxidation of 5-hydroxymethylfurfural, a versatile biomass-derived chemical, is examined in water with a titania-supported gold-nanoparticle catalyst at ambient temperature (30 °C). The selectivity of the reaction towards 2,5-furandicarboxylic acid and the intermediate oxidation product 5-hydroxymethyl-2-furancarboxylic acid is found to depend on the amount of added base and the oxygen pressure, suggesting that the reaction proceeds via initial oxidation of the aldehyde moiety followed by oxidation of the hydroxymethyl group of 5-hydroxymethylfurfural. Under optimized reaction conditions, a 71% yield of 2,5-furandicarboxylic acid is obtained at full 5-hydroxymethylfurfural conversion in the presence of excess base.

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