PRODUCTION OF 1,3-PROPANEDIOL FROM GLYCEROL BY NEWLY ISOLATED STRAINS OF KLEBSIELLA PNEUMONIAE

Three novel Klebsiella pneumoniae subsp. pneumoniae strains G9, G31 and G46, capable to convert glycerol into high amounts of 1,3-propanediol (1,3-PD) and 2,3-butanediol (2,3-BD) were isolated, identified and studied in a series of batch processes. The improvement of media content and cultivation conditions revealed that factors as stirring rate, pH and acetate accumulation possessed most important influence on the fermentation. Substrate decrease kinetics of cultures, stirred at different speed showed that the vigorous stirring strongly accelerated the process of glycerol degradation. The complete glycerol consumption was also dependent on the strains' ability to secrete lower amounts of acids, particularly acetic acid. The best glycerol consumer G31 formed acetate almost thrice less than G46 (and twice less than G9) and subsequently converted it in nonacidic compounds. Comparative experiments without pH control and with pH, maintained at 7 showed that the neutral pH directed the process to increase of 1,3-PD amounts and to remarkable decrease of 2,3-BD production. Thus, the strains G31 and G46 achieved 25.86 and 21.42 g/l 1,3-PD from 50 g/l glycerol, along with 1.7 and 0.0 g/l 2,3-BD, respectively. To our knowledge, the value of 1,3-PD, produced by G31, comprising yield of 62.6 mol/100 mol glycerol is the highest reported for a Klebsiella strain in batch process until now.