화학공학소재연구정보센터
Applied Biochemistry and Biotechnology, Vol.192, No.4, 1147-1162, 2020
Construction of RecombinantKlebsiella pneumoniaeto Increase Ethanol Production on Residual Glycerol Fed-Batch Cultivations
K. pneumoniaeBLh-1 strain was genetically modified aiming at obtaining high ethanol productivity in cultivations using residual glycerol from biodiesel synthesis as substrate. The recombinant strainK. pneumoniaeKp17 was obtained by inserting the multicopy plasmid pTOPOBL17 containing the AdhE gene, and its own promoter, fromK. pneumoniaeBLh-1. Influence of Fe(2+)supplementation and initial glycerol concentration on culture conditions were analyzed, both in rotatory shaker and in batch bioreactors. In the bioreactor cultures,K. pneumoniaeKp17 strain produced 4.5 g L(-1)of ethanol (productivity of 0.50 g L-1 h(-1)and yields of 0.15 g g(-1)) after 24-h cultivation, corresponding to an increase of approximately 40% in ethanol concentration compared to wild strain,K. pneumoniaeBLh-1. Best conditions were then applied in exponential fed-batch bioreactors, with final ethanol concentration of 17.30 g L-1(productivity of 0.59 g L-1 h(-1)and yields of 0.16 g g(-1)) after 30 h of feeding, representing 11.5% of increment in titer of ethanol compared to the wild strain. Mutant cells kept 92.5% of the plasmids under batch in 24 h, and 71.9% under fed-batch after 27 h of exponential feeding. The findings in this work show the possibility of using a simple approach to genetically modifyK. pneumoniaeto be employed this versatile bacterium for the bioconversion of residual glycerol into ethanol.