Nicotinic acid microbial hydroxylation

Substituted nicotinic acid derivatives, such as 6-hydroxy nicotinic acid are important building blocks for the synthesis of pesticides and pharmaceuticals, acting as specific inhibitors of NAD/NADP-dependent enzymes. In a process developed by Lonza (Switzerland), 6-hydroxy nicotinic acid is produced by whole-cell microbial hydroxylation of nicotinic acid with Achromobacter xylosoxidans (yield > 100 g 1 ) (Fig. 16). A similar process for the production of 6-hydroxypicolinic acid (98 g l-1) and derivatives from picolinic acid (derivatives), based on Alcaligenes faecalis, has also been established [174,175]. 

The 3,6-diposition-substituted pyridine compounds are important intermediates for industrial synthesis, especially for production of some agricultural chemicals. This compound can be obtained by chemically synthesized from pyridine, but the process is accompanied by some by-products. Microbial hydroxylation of aromatic compounds is a very efficient method of regioselective reaction. Several methods have been reported for the preparation of 3,6-disubstituted pyridine using microorganisms. In 1985, Lehky et al. reported the microbial production of 6-hydroxynicotinic acid (6-HNA) from nicotinic acid (NA) by Achromobacter xylosoxydans Nagasawa et al. also prepared 6-HNA from NA by using Pseudomonas fluorescens TN5. 

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