Reduction of aliphatic nitro groups using an obligately anaerobic whole cell biocatalyst

Peptostreptococcus productus U-1 was grown in a fructose-limited chemostat with caffeate (D = 0.19 h−1), and washed, harvested cells were used to reduce (E)-2-nitro-1-phenyl-1-propene 1a and (E)-2-nitro-1-phenyl-1-butene 1b in a two-liquid phase reaction system. The aminoalkanes 3a and 3b were formed in 47% and 7.5% yield, respectively, by reduction of both the aliphatic nitro group and the C–C double bond. Direct reduction of a nitroalkane was also demonstrated using synthetic, racemic 2a, which was reduced to 3a in 45% yield. Optimum activity was obtained with 1a provided at 2.5 mM (0.25 mmol and 0.041 g) at a scale of 100 mL, at pH 7.0. The reaction was complete in 24 h using only 0.66 gdry weight biocatalyst L−1, and the rate of aliphatic nitro reduction was up to 154 mmol (25.1 g) (kgdry weight h)−1.