Production of ( R)-3-hydroxybutyric acid by fermentation and bioconversion processes with Azohydromonas lata

Abstract

Feasibility of producing ( R)-3-hydroxybutyric acid (( R)-3-HB) using wild type Azohydromonas lata and its mutants (derived by UV mutation) was investigated. A. lata mutant (M5) produced 780 mg/l in the culture broth when sucrose was used as the carbon source. M5 was further studied in terms of its specificity with various bioconversion substrates for production of ( R)-3-HB. ( R)-3-HB concentration produced in the culture broth by M5 mutant was 2.7-fold higher than that of the wild type strain when sucrose (3% w/v) and ( R,S)-1,3-butanediol (3% v/v) were used as carbon source and bioconversion substrate, respectively. Bioconversion of resting cells (M5) with glucose (1% v/w), ethylacetoacetate (2% v/v), and ( R,S)-1,3-butanediol (3% v/v), resulted in ( R)-3-HB concentrations of 6.5 g/l, 7.3 g/l and 8.7 g/l, respectively.