A Combined Hydroxylation of 3-Cyanopyridine to 3-Cyano-6-hydroxypyridine and 6-Hydroxynicotinic Acid by Resting Cells ofComamonas testosteroni JA1 Grown on Nicotinic Acid

A strain of Comamonas testosteroniJAl known for its capacity to hydroxylate 3-cyanopyridine to 3-cyano-6-hydroxypyridine was found to be also capable to hydroxylate nicotinic acid at a higher rate. In the course of the induced cultivation the forming 6-hydroxynicotinic acid was degraded either slightly, in the presence of nicotinic acid in the medium, or faster, in the absence of nicotinic acid. In a combined process of hydroxylation of nicotinic acid by growing culture and hydroxylation of 3-cyanopyridine by resting cells of Cornamonas testosteroni JA1, not only an additional amount of 50.38 g of solid 6-hydroxynicotinic acid was produced from 1 L of cultivation broth with a 99.97 % molar conversion yield, but also the yield of 3-cyano-6-hydroxypyridine produced was more than doubled. This can be compared to that of the resting cells from the induced cultivation broth where within 8 h an amount of 5.77 g of solid 3-cyano-6-hydroxypyridine was produced by resting cells from 1 L of the cultivation broth. This also was superior to 4.39 g/L of cultivation broth of resting cells reported in the literature.