1,3-Propanediol production by Klebsiella oxytoca NRRL-B199 from glycerol. Medium composition and operational conditions

Abstract

Production of 1,3-propanediol from glycerol using Klebsiella oxytoca NRRL-B199 has been studied. Medium composition has been optimized by means of a statistical design based on the Taguchi method. Strong influences of glycerol and phosphate concentrations have been detected on biomass and product yields. Other factors, such as magnesium concentration and K:Na ratio, have shown a small influence on both responses, biomass and product concentrations. An optimized medium composition has been proposed, leading to a final 1,3-propanediol concentration of 12.4 g/L with a selectivity of 72% with respect to glycerol consumed at shaken bottle-scale. Once the medium composition had been optimized, the scale-up from shaken bottles to STBR was conducted. Several experiments in a 2 L STBR have been conducted in order to determine the best operating conditions concerning temperature and agitation. Under the best operating conditions, i.e., a programmed variable stirring rate ranging from 50 to 100 rpm and a temperature of 37 C, a final concentration of 13.5 g/L of 1,3-propanediol with a selectivity of 86% with respect to the glycerol consumed was obtained.