Conversion of glycerol to 1,3-propanediol by Citrobacter freundii and Hafnia alvei - newly isolated strains from the Enterobacteriaceae

In this study, nearly 4000 bacterial strains from the family of Enterobacteriaceae isolated from different environments were screened for ability to convert glycerol to 1,3-propanediol (1,3-PD). The aim of the research was to isolate 1,3-PD producers from the natural environment, identify and characterize the best isolates. Three selective media were tested to usefulness in the isolation of bacteria from the family Enterobacteriaceae. Only, 28% of examined isolates could synthesize 1,3-PD from glycerol. 1,3-PD producing bacteria were identified by API 20E tests and 16S rRNA sequences to be Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter freundii and Hafnia alvei. It is the first time, when the fermentation glycerol to 1,3-PD by H. alvei was investigated. The selected strains (C. freundii AD119 and H. alvei AD27) were analyzed on a bioreactor scale under constant pH value 7.0 at temperature of 30°C and 37°C. After 40 h in batch fermentation, H. alvei AD27 produced 11.3 g/L of 1,3-PD at 37°C. For C. freundii AD119, the best results were obtained at temperature of 30°C. After 24 h of fermentation, the 1,3-PD concentration reached above 23 g/L of 1,3-PD.