Physiologic Mechanisms Involved in Accumulation of 3-Hydroxypropionaldehyde during Fermentation of Glycerol by Enterobacter agglomerans

Abstract

When grown in 700 mM glycerol within the pH range 6.0 to 7.5, anaerobic pH-regulated cultures of Enterobacter agglomerans exhibited an extracellular accumulation of 3-hydroxypropionaldehyde (3-HPA). This phenomenon, which causes fermentation cessation, occurred earlier when pH was low. In contrast, substrate consumption was complete at pH 8. Levels of glycerol-catabolizing enzymes, i.e., glycerol dehydrogenase and dihydroxyacetone kinase for the oxidative route and glycerol dehydratase and 1,3-propanediol dehydrogenase for the reductive route, as well as the nucleotide pools were determined periodically in the pH 7-and pH 8-regulated cultures. A NAD/NADH ratio of 1.7 was correlated with the beginning of the production of the inhibitory metabolite. Further accumulation was dependent on the ratio of glycerol dehydratase activity to 1,3-propanediol dehydrogenase activity. For a ratio higher than 1, 3-HPA was produced until fermentation ceased, which occurred for the pH 7-regulated culture. At pH 8, a value below 1 was noticed and 3-HPA accumulation was transient, while the NAD/NADH ratio decreased. The low rate of glycerol dissimilation following the appearance of 3-HPA in the culture medium was attributed to the strong inhibitory effect exerted by 3-HPA on glycerol dehydrogenase activity.

Uncoupled glycerol distribution as the origin of the accumulation of 3-hydroxypropionaldehyde during the fermentation of glycerol byEnterobacter agglomerans CNCM 1210

“…A physiological approach, based on the evolution of DHAP, GAP, and FDP intracellular concentrations and of GAP dehydrogenase activity, was followed in addition to the NAD and NADH content profiles. Displayed in Figure 2, it showed that NADH concentration remained constant at 6.0 mol.g −1 during phase I of the fermentation, in contrast to NAD whose intracellular content increased from 8.3 to 10.4 mol.g −1 , concommitantly to the increases of activities of glycerol dehydratase and 1,3PPD dehydrogenase to 2.0 and 1.3 U.mg −1 , respectively, as already mentioned (Barbirato et al, 1996b). In addition, while the level of activity of GAP dehydrogenase did not change significantly (about 2.2 U.mg −1 ), DHAP concentration showed a continuous increase from 16.3 mol.g −1 to 31.3 mol.g −1 .…”

“…International, Melsungen, Germany) regulated at 30°C and pH 7. Composition, preparation, sterilization, deaeration, and inoculation of the medium were as described previously (Barbirato et al, 1996b).…”

“…Such behavior was also observed during the fermentation of glycerol by K. pneumoniae and C. freundii. Investigated with E. agglomerans, the accumulation of 3-HPA was associated with an increase of the NAD/NADH ratio to 1.7, provoking a partial inhibition of 1,3PPD dehydrogenase (Barbirato et al, 1996b), which was supported by the competitive inhibition exerted by NAD with respect to NADH on the purified 3-HPA converting enzyme (Barbirato et al, 1997b). The effects on the central metabolism of E. agglomerans of the specific rate of glycerol consumption have been investigated by operating chemostat cultures at high growth and glycerol dissimilation rates.…”

Use of ceramic-based cell immobilization to produce 1,3-propanediol from biodiesel-derived waste glycerol with Klebsiella pneumoniae

“…1998; Seifert et al. 2001), Enterobacter (Barbirato et al. 1995, 1996; Barbirato and Bories 1997; Barbirato et al.…”

Crescimento e caracterização enzimática de bactérias probióticas em meio contendo glicerol e seu encapsulamento em matriz polimérica natural

“…Em espécies de bactérias como Clostridium pasteurianum, Citrobacter freundii, Lactobacillus brevis, Lactobacillus buchnerii e Bacillus welchii (BARBIRATO et al, 1996;DABROCK et al, 1992;GONZÁLEZ-PAJUELO et al, 2005;NAKAMURA et al, 2000); sob condições de anaerobiose, o glicerol sofre desidratação pela enzima glicerol desidratase para produzir 3dihidroxipropionaldeído. Posteriormente, este intermediário é transformado pela enzima 1,3-propanodiol oxido-reductase NADH dependente em 1,3-propanodiol, principal intermediário para produção de polímeros, resinas e aditivos de importantes aplicações industriais (GONZÁLEZ-PAJUELO et al, 2005;YAZDANI;GONZALEZ, 2007).…”