S47: Improvement of biotransformation and natural product yields by medium and process optimization

The diverse nature of fermentation-related projects often demands that an equally diverse set of approaches be utilized to generate sufficient quantities of desired products.  Several examples of improvements achieved in processes ranging from natural product fermentation to biotransformation will be discussed.  The natural product sordarin, an antifungal diterpene glycoside produced by Sordaria araneosa, was initially produced at levels of ca. 100 µg/g. Through various strategies including medium optimization, flask yields were increased 25-fold to over 2500 µg/g and successfully scaled to tanks.   Biotransformation of 2-amino-4-methyl-3-nitropyridine by Cunninghamella elegans ATCC 26269 yielded three [M+16] products consistent with hydroxylation, while a second organism, Streptomyces antibioticus ATCC 14890, produced two additional products with the same molecular weight (169 Da).  To improve the 5-hydroxylation product yield by Cunninghamella, studies were performed to determine key process parameters.  The results facilitated successful scale-up of the biotransformation to 15-L fermentors and production of gram quantities of 2-amino-5-hydroxy-4-methyl-3-nitropyridine.  In a second biotransformation reaction involving the enzymatic O-demethylation of the factor Xa inhibitor Apixaban, preliminary studies had demonstrated that strains of both Cunninghamella and Nocardioides could produce the desired product, albeit at very low (<5%) levels.  Follow-up medium and process optimization studies using Nocardioides albus led to an increase in product yield to ca. 80%.