Biodiesel residual glycerol metabolism by Klebsiella pneumoniae: pool of metabolites under anaerobiosis and oxygen limitation as a function of feeding rates.
The metabolism of residual glycerol from biodiesel synthesis by Klebsiella pneumoniae BLh-1 was investigated in this study. Batch and fed-batch cultivations were performed in bioreactors under anaerobic and oxygen limitation conditions. Results of batch cultivations showed that the main product was 1,3-propanediol (1,3-PD) in both conditions, although the higher yields and productivities (0.46 mol mol(-1) glycerol and 1.22 g L(-1) h(-1), respectively) were obtained under anaerobic condition. Large amounts of ethanol were also produced under batch anaerobic condition, peaking at 12.30 g L(-1). Batch cultivations under oxygen limitation were characterized by faster growth kinetics, with higher biomass production but lower conversions of glycerol into 1,3-PD, with yields and productivities of 0.33 mol mol(-1) glycerol and 0.99 g L(-1) h(-1), respectively. The fed-batch cultivations were carried out in order to investigate the effects of feeding of raw glycerol on cells. Fed-batch under anaerobiosis showed that 1,3-PD and ethanol concentrations increased with the feeding rate, with maximal productions of 26.12 and 19.2 g L(-1), respectively. The oxygen limitation conditions diverted the bacterium metabolism to an elevated lactic acid formation, reaching 59 g L(-1) in higher feeding rates of glycerol, but lowering the production of ethanol.
Biotechnology & Biochemical Engineering Laboratory (BiotecLab), Federal University of Rio Grande do Sul, Av. Bento Gonçalves 9500, Porto Alegre, Rio Grande do Sul, Brazil.
Daniele Misturini
DM
Rossi
Elisangela Aquino
EA
de Souza
Marco Antônio Záchia
MA
Ayub
D000693:Anaerobiosis; D061249:Batch Cell Culture Techniques / Q000379:methods*; D056804:Biofuels; D005990:Glycerol / Q000378:metabolism* / Q000494:pharmacology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*
D056804:Biofuels; D005990:Glycerol; D010100:Oxygen