초록
<P><B>Background</B></P><P>As 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).</P><P><B>Results</B></P><P>The study investigated the scale-up of 1,3-PD synthesis from crude glycerol by <I>Clostridium butyricum</I>. Batch fermentations were carried out in 6.6 L, 42 L and 150 L bioreactors. It was observed that cultivation of <I>C. butyricum</I> 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.</P><P><B>Conclusion</B></P><P>The 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.</P>