Sustainable Biosynthesis of Fludarabine by a Novel Mixed Nanostabilized Biocatalyst

The purine analogue, 2-fluoroadenine-9-β-D-arabinofuranoside, better known as fludarabine, is a widely used drug for cancer treatment. Nowadays, it is mainly synthesized by chemical methods, but it has been proved that biocatalysis has several advantages over chemical synthesis. In this work, Cellulosimicrobium cellulans was studied due to its fludarabine biosynthesis ability, inferring the activity of a NDT type II enzyme capable of using arabinose as sugar donor. Reaction parameters were optimized, achieving bioconversion rates of 75% at two hours, significantly higher than previously reported. Additionally, various mixed entrapment techniques for whole-cell immobilization were analyzed as a strategy to stabilize the biocatalyst for potential industrial applications. Natural matrices such as agar, agarose, and alginate combined with different nanocomposites were assayed. Finally, we developed an innovative mixed nanobiocatalyst using an agarose matrix to which a mixture of nanocomposites bentonite and montmorillonite was added. We characterized the biocatalyst to demonstrate that the nanocomposite and Cellulosimicrobium cellulans cells were successfully incorporated into the matrix. The developed mixed biocatalyst was able to synthesize more than 59% of fludarabine in six hours of reaction and its reusability under operational conditions was improved more than tenfold. This technology offers an efficient, cheap and sustainable method for producing fludarabine, with the potential to meet regional demand and reduce reliance on pharmaceutical monopolies.