Scale-Up of Phytosterols Bioconversion into Androstenedione

Phytosterols, generated as a by-product of vegetable oils or wood pulp, contain the cyclopentane-perhydro-phenanthrene nucleus, and can be converted into steroid intermediates by removing the C17 side chain. This chapter shows the scale-up, from flask to fermentor, of the phytosterols bioconversion into 4-androstene-3,17-dione (androstenedione; AD) with Mycobacterium neoaurum B-3805. Due to the fact that phytosterols and AD are nearly insoluble in water, two-phase systems and the use of chemically modified cyclodextrins have been described as methods to solve it. Here we use a water-oil two-phase system that allows for the bioconversion of up to 20 g/L of phytosterols into AD in 20 L fermentor.