[Microplate for high throughput screening of 6-hydroxynicotinic acid transforming strains].

Recently, new insecticides containing 3-chloropyridylmethyl group as a versatile building block have been developed, among which imidachloprid is a promising one. The synthesis of imidachloprid can use 6-Hydroxynicotinic acid, the first intermediate of the bacterial degradation of nicotinic acid, as a starting material. It is difficult to hydroxylate nicotinic acid at C6 position in a chemical synthesis. However, biotransformation can produce 6-hydroxynicotinic acid with industrial application possibility. Therefore, methods for large scale screening of 6-hydroxynicotinic acid-producing microorganisms are urgent. A high through-put screening method for 6-hydroxynicotinic acid transforming strains was established by determining 6-hydroxynicotinic acid based on 96-well Microplate-Multiskan Spectrum. The determination wavelength and the reference wavelength of 6-hydroxynicotinic acid were 251nm and 231nm respectively. Beer's law is obeyed in the range of 0.5-11 microg/mL (R2 = 0.9999) for measuring 6-hydroxynicotinic acid. The average recovery rate was 99.11%-100.81%. The results showed that there was no apparent difference between our microplate method and previous HPLC method in the detecting 6-hydroxynicotinic acid formation. The microplate method is simple, convenient and accurate. It has the potential for large scale (about 2000 - 5000 reactions/d) screening of 6-hydroxynicotinic acid-producing microorganisms.