Scale-up of anaerobic 1,3-propanediol production by Clostridium butyricum DSP1 from crude glycerol

Abstract

BackgroundAs the production of biofuels from raw materials continuously increases, optimization of production processes is necessary. A very important issue is the development of wasteless methods of biodiesel production. One way of utilization of glycerol generated in biodiesel production is its microbial conversion to 1,3-PD (1,3-propanediol).ResultsThe study investigated the scale-up of 1,3-PD synthesis from crude glycerol by Clostridium butyricum. Batch fermentations were carried out in 6.6 L, 42 L and 150 L bioreactors. It was observed that cultivation of C. butyricum on a pilot scale did not decrease the efficiency of 1,3-PD production. The highest concentrations of 1,3-PD, 37 g/L for batch fermentation and 71 g/L for fed-batch fermentation, were obtained in the 6.6 L bioreactor. The kinetic parameters of 1,3-PD synthesis from crude glycerol established for batch fermentation were similar regarding all three bioreactor capacities. During fed-batch fermentation, the concentration of 1,3-PD in the 150 L bioreactor was lower and the substrate was not completely utilized. That suggested the presence of multifunctional environmental stresses in the 150 L bioreactor, which was confirmed by protein analysis.ConclusionThe values of effectivity parameters for 1,3-PD synthesis in batch fermentations carried out in 6.6 L, 42 L and 150 L bioreactors were similar. The parameters obtained during fed-batch fermentations in the 150 L bioreactor differed in the rate and percentage of substrate utilization. The analysis of cell proteins demonstrated that a number of multifunctional stresses occurred during fed-batch fermentations in the 150 L bioreactor, which suggests the possibility of identifying the key stages in the biochemical process where inhibition of 1,3-PD synthesis pathways can be observed.

Adaptive evolution of Clostridium butyricum and scale‐Up for high‐Concentration 1,3‐propanediol production

“…As described by Zhang et al and Zeng et al, 1,3‐PDO production was an NADH‐needing process, and the NADH came from glycerol oxidative pathways which would synthesize acids, such as butyric acid and acetic acid, finally. Szymanowska‐Powalowska and Białas reported that 1,3‐PDO bioconversion process could be influenced by osmotic stress (high concentrations of glycerol), toxic stress (high concentrations of organic acids and 1,3‐PDO), mechanical stress and oxidative stress. Biebl and Szymanowska‐Powalowska also presented the similar findings that high concentration of butyric acid and acetic acid inhibited the production of 1,3‐PDO by C. butyricum when pH was maintained at 6.5.…”

“…By contrast, owing to the longer time of feeding in fed‐batch fermentation process, the productivity of 1,3‐PDO in batch fermentation strategy was higher, while the concentration of 1,3‐PDO was higher than that in batch process. Chatzifragkou et al and Szymanowska‐Powalowska and Białas selected strains with high performance of 1,3‐PDO production (70.8 g/L and 71 g/L respectively) through fed‐batch strategy. Compared with processes above, whether in batch or fed‐batch process, the adaptive evolution strain could not only obtain the same excellent performance in 1,3‐PDO production (66.23 g/L), but also consume less time with better productivity.…”

1,3-Propanediol production from crude glycerol by Clostridium butyricum DSP1 in repeated batch

“…The biotechnological methods that have been designed to obtain 1,3-PD by converting glycerol use the bacteria of the genera Clostridium, Klebsiella, Citrobacter, Hafnia, Lactobacillus [6,7,8]. In the process of selecting a 1,3-PD producer, consideration must be given not only to such vital features as resistance to osmotic, toxic, and mechanical stresses or maintenance of growth capability under the conditions of industrial-scale synthesis but also to an appropriate cultivation method [9,10]. The choice of a culturing protocol is mainly determined by the cost of fermentation medium (substrate included) and by process specifications, e.g.…”

A novel kinetic model to describe 1,3‐propanediol production fermentation by Clostridium butyricum

“…Fermentative production of 1,3-PDO by C. butyricum has been extensively studied and achieved success in repeated batch, two-stage temperature control, and immobilization system in the past decades. 7,13,14 However, many byproducts have a negative effect which come from osmotic stress, toxic stress, and feedback inhibition 15 on growth and 1,3-PDO production. The relatively low 1,3-PDO content in the final product is still a major barrier that limits the product quality and scale-up.…”