IntroductionBy definition, biocatalysis is the use of natural catalysts to mediate chemical transformations in applications for which they did not naturally evolve. However, biocatalysis encompasses a continuum of two distinct but closely related subfields: biotransformation and fermentation. Here, we will focus on the application of biocatalysts as biotransformants and review the history and scope of biocatalysis in biochemical engineering. The use of biocatalysts offers great promise in synthetic chemistry processes, but exploiting its potential for industrial applications has depended heavily on advances in biotechnological innovations, both to improve our understanding of how biocatalysts work and to evolve new engineering strategies. As a result, biocatalysis has become a key tool over the past decade to expand applications in the biochemical industry. Evolution of Biocatalysis The use of enzyme catalysts that mediate fermentation for the production and preservation of food products is known to predate recorded history. Among others, a milestone in the field of enzyme technology was the use of cell-free yeast extracts (now known as zymase enzyme) for the fermentation of sugar by Eduard Buchner: this debunked the often cited idea according to which the presence of living cells is a necessary requirement for biotransformation[1][2]. The paradigm shift towards biocatalysis in synthetic chemistry originated in the production of (R)-mandelonitrile from benzaldehdye and hydrocyanic acid in the presence of a bitter almond emulsion extract (a mixture of enzymes containing oxynitrilases) by Rosenthaler, the first demonstration of modern biocatalysis [1] [3] [4] [32]. Like ...... half of the document ...... 01, March 2008.[28] M. Njoroge and C. Masimirembwa, “Biotransformation and biocatalysis: roles and applications in antimalarial discovery,” Futur. Med. Chemistry, vol. 4, pp. 2325–2336, 2012.[29] S. M. Thomas, R. Dicosimo, and V. Nagarajan, “Biocatalysis: Applications and Potential for the Chemical Industry,” Trends Biotechnol., vol. 20, no. 6, pp. 238–242, 2002.[30] M. Alcalde, M. Ferrer, FJ Plou and A. Ballesteros, “Environmental biocatalysis: from enzyme remediation to new green processes.” Trends Biotechnol., vol. 24, no. 6, pp. 281–7, June 2006.[31] Robles-Medina, P. González-Moreno, L. Esteban-Cerdán, and E. Molina-Grima, “Biocatalysis: Towards Ever Greener Biodiesel Production.” Biotechnol. Lawyer, vol. 27, no. 4, pp. 398–408, 2009.[32] Rosenthaler L. Asymmetric syntheses produced by enzymes. Biochemistry Z. 1908; 14: 238–253