P8: Influence of glycerol level on 3-hydroxypropionaldehyde production by three related enteric species

The commercially valuable specialty chemical 3-hydroxypropionaldehyde has several applications including the production of plastics. Three species of Enterobacter, including E. aerogenes ATCC 13048, E. cloacae ATCC 13047 and E. agglomerans ATCC 27155, were used to determine the influence of glycerol concentration on 3-hydroxypropionaldehyde production. The three strains were grown in a complex medium containing 2.5% or 5% glycerol for 24 hours at 28^oC. The cells were collected by centrifugation and resuspended in a neutral phosphate buffer containing the same concentration of glycerol and 0.75% semicarbazide hydrochloride. Semicarbazide hydrochloride prevents the degradation of the aldehyde into 1,3-propanediol by inhibiting a bacterial reductase. After the cell suspensions were shaken for 24 hours at 28^oC, the cells were collected by centrifugation. The aldehyde level in the supernatant of each suspension was measured utilizing a spectrophotometric assay. It was found that the highest 3-hydroxypropionaldehyde concentration was produced by the three strains when 2.5% glycerol was present in the buffer. A drop in 3-hydroxypropionaldehyde production by the three strains was noted when 5% glycerol was present in the buffer. Of the species tested, E. aerogenes produced the highest 3-hydroxypropionaldehyde level at either glycerol concentration examined. In summary, 3-hydroxypropionaldehyde production by three species of Enterobacter was shown to decrease when the level of glycerol present doubled in concentration.