Significant impact of casein hydrolysate to overcome the low consumption of glycerol by Klebsiella aerogenes ATCC 29007 and its application to bioethanol production

Ju Hun Lee, Hah Young Yoo, Soo Kweon Lee, Youngsang Chun, Hyeong Ryeol Kim, Wichanee Bankeeree, Pongtharin Lotrakul, Hunsa Punnapayak, Sehanat Prasongsuk, Seung Wook Kim

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


As the demand for biodiesel increases, the by-product glycerol is increasing. Biodiesel-derived glycerol is expected to be applied in bioindustries. However, major limitation of industrial fermentation is that the rate of substrate consumption is significantly slower than conventional process. In this study, in order to improve the consumption of refined crude glycerol in Klebsiella aerogenes, casein hydrolysate was supplemented in main medium. As a result, the substrate consumption rate, cell and ethanol concentration were improved about 2.6-fold, 2.5-fold and 3.0-fold, respectively, compared with the control group. In addition, four components of the main medium (peptone, ammonium sulfate, casein hydrolysate, refined crude glycerol) were statistically optimized. The consumption of glycerol was achieved about 89%, and the productivity of bioethanol was found to be 0.83 g/(L h) under the optimized medium. Also, the bioethanol concentration and yield were 15.89 g/L and 0.487 (g/g), respectively. The supplementation of casein hydrolysate had a significant effect on fermentation. It was proved by analyzing the concentration of free amino acids contained in casein hydrolysate. As a result, it was found that glycerol consumption and bioethanol production were promoted by the abundant supply of essential amino acids contained in casein hydrolysate for cell growth. Therefore, these results will be the basis for sustainable development by providing the opportunity to reuse crude glycerol for industrial applications.

Original languageEnglish
Article number113181
JournalEnergy Conversion and Management
Publication statusPublished - 2020 Oct 1

Bibliographical note

Funding Information:
This work was supported by Korea University Grant and the National Research Foundation of Korea (NRF) grant funded by the Korean Government (NRF-2019R1A2C1006793 and 2020R1C1C1005060).

Publisher Copyright:
© 2020 Elsevier Ltd


  • Bioethanol
  • Biorefinery
  • Casein hydrolysate
  • Glycerol
  • Klebsiella aerogenes

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology


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