Sunday, May 3, 2009
2-69
Effect of soy-based glycerol concentration on 3-hydroxypropionaldehyde production by enteric species
Thomas P. West, Biology and Microbiology, South Dakota State University, Box 2207B, Brookings, SD 57007
During soy biodiesel production, a coproduct stream containing glycerol, fatty acid and methylesters of fatty acids results. Raw glycerol is the major coproduct formed during the processing of crude soybean oil to biodiesel. Raw glycerol is considered a low value product but can serve as a substrate for the microbial fermentation of the specialty chemical 3-hydroxypropionaldehyde. This specialty chemical is a precursor for plastic production and has other uses as a food preservative and a tissue fixative. In this investigation, the ability of selected enteric bacteria to convert different concentrations of soy-based raw glycerol to 3-hydroxypropionaldehyde was analyzed. Using a complex medium containing diluted raw glycerol, the enteric bacteria were grown for 24 hours at 28oC. After the cells were collected by centrifugation, they were resuspended in a neutral phosphate buffer containing diluted raw glycerol and semicarbazide hydrochloride. Following the cell suspension being shaken for 24 hours at 28oC, the cells were collected by centrifugation and the resultant supernatant of each suspension was colorimetrically assayed for 3-hydroxypropionaldehyde. The enteric bacterium Citrobacter freundii ATCC 8090 produced more than double the concentration of 3-hydroxypropionaldehyde on 10% raw glycerol than on 5% raw glycerol. In contrast, Enterobacter aerogenes ATCC 13048 produced more than double the concentration of 3-hydroxypropionaldehyde on 5% raw glycerol than on 10% raw glycerol. Overall, it was shown that the concentration of raw glycerol used to grow enteric species can affect the level of the specialty chemical 3-hydroxypropionaldehyde produced.