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Acetate accumulation enhances mixed culture fermentation of biomass to lactic acid

Way Cern Khor (UGent) , Hugo Roume (UGent) , Marta Coma (UGent) , Han Vervaeren (UGent) and Korneel Rabaey (UGent)
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Abstract
Lactic acid is a high-in-demand chemical, which can be produced through fermentation of lignocellulosic feedstock. However, fermentation of complex substrate produces a mixture of products at efficiencies too low to justify a production process. We hypothesized that the background acetic acid concentration plays a critical role in lactic acid yield; therefore, its retention via selective extraction of lactic acid or its addition would improve overall lactic acid production and eliminate net production of acetic acid. To test this hypothesis, we added 10 g/L of acetate to fermentation broth to investigate its effect on products composition and concentration and bacterial community evolution using several substrate-inoculum combinations. With rumen fluid inoculum, lactate concentrations increased by 80 +/- A 12 % (cornstarch, p < 0.05) and 16.7 +/- A 0.4 % (extruded grass, p < 0.05) while with pure culture inoculum (Lactobacillus delbrueckii and genetically modified (GM) Escherichia coli), a 4 to 23 % increase was observed. Using rumen fluid inoculum, the bacterial community was enriched within 8 days to > 69 % lactic acid bacteria (LAB), predominantly Lactobacillaceae. Higher acetate concentration promoted a more diverse LAB population, especially on non-inoculated bottles. In subsequent tests, acetate was added in a semi-continuous percolation system with grass as substrate. These tests confirmed our findings producing lactate at concentrations 26 +/- A 5 % (p < 0.05) higher than the control reactor over 20 days operation. Overall, our work shows that recirculating acetate has the potential to boost lactic acid production from waste biomass to levels more attractive for application.
Keywords
ESCHERICHIA-COLI, Mixed culture, ACETIC-ACID, LACTOBACILLUS-PLANTARUM, GLYCEROL FERMENTATION, ENERGY-CONSERVATION, GROWTH, RUMEN, PH, INHIBITION, COMMUNITY, Lactic acid, Acetate, Lignocellulosic biomass

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MLA
Khor, Way Cern, et al. “Acetate Accumulation Enhances Mixed Culture Fermentation of Biomass to Lactic Acid.” APPLIED MICROBIOLOGY AND BIOTECHNOLOGY, vol. 100, no. 19, 2016, pp. 8337–48, doi:10.1007/s00253-016-7578-5.
APA
Khor, W. C., Roume, H., Coma, M., Vervaeren, H., & Rabaey, K. (2016). Acetate accumulation enhances mixed culture fermentation of biomass to lactic acid. APPLIED MICROBIOLOGY AND BIOTECHNOLOGY, 100(19), 8337–8348. https://doi.org/10.1007/s00253-016-7578-5
Chicago author-date
Khor, Way Cern, Hugo Roume, Marta Coma, Han Vervaeren, and Korneel Rabaey. 2016. “Acetate Accumulation Enhances Mixed Culture Fermentation of Biomass to Lactic Acid.” APPLIED MICROBIOLOGY AND BIOTECHNOLOGY 100 (19): 8337–48. https://doi.org/10.1007/s00253-016-7578-5.
Chicago author-date (all authors)
Khor, Way Cern, Hugo Roume, Marta Coma, Han Vervaeren, and Korneel Rabaey. 2016. “Acetate Accumulation Enhances Mixed Culture Fermentation of Biomass to Lactic Acid.” APPLIED MICROBIOLOGY AND BIOTECHNOLOGY 100 (19): 8337–8348. doi:10.1007/s00253-016-7578-5.
Vancouver
1.
Khor WC, Roume H, Coma M, Vervaeren H, Rabaey K. Acetate accumulation enhances mixed culture fermentation of biomass to lactic acid. APPLIED MICROBIOLOGY AND BIOTECHNOLOGY. 2016;100(19):8337–48.
IEEE
[1]
W. C. Khor, H. Roume, M. Coma, H. Vervaeren, and K. Rabaey, “Acetate accumulation enhances mixed culture fermentation of biomass to lactic acid,” APPLIED MICROBIOLOGY AND BIOTECHNOLOGY, vol. 100, no. 19, pp. 8337–8348, 2016.
@article{7235522,
  abstract     = {{Lactic acid is a high-in-demand chemical, which can be produced through fermentation of lignocellulosic feedstock. However, fermentation of complex substrate produces a mixture of products at efficiencies too low to justify a production process. We hypothesized that the background acetic acid concentration plays a critical role in lactic acid yield; therefore, its retention via selective extraction of lactic acid or its addition would improve overall lactic acid production and eliminate net production of acetic acid. To test this hypothesis, we added 10 g/L of acetate to fermentation broth to investigate its effect on products composition and concentration and bacterial community evolution using several substrate-inoculum combinations. With rumen fluid inoculum, lactate concentrations increased by 80 +/- A 12 % (cornstarch, p < 0.05) and 16.7 +/- A 0.4 % (extruded grass, p < 0.05) while with pure culture inoculum (Lactobacillus delbrueckii and genetically modified (GM) Escherichia coli), a 4 to 23 % increase was observed. Using rumen fluid inoculum, the bacterial community was enriched within 8 days to > 69 % lactic acid bacteria (LAB), predominantly Lactobacillaceae. Higher acetate concentration promoted a more diverse LAB population, especially on non-inoculated bottles. In subsequent tests, acetate was added in a semi-continuous percolation system with grass as substrate. These tests confirmed our findings producing lactate at concentrations 26 +/- A 5 % (p < 0.05) higher than the control reactor over 20 days operation. Overall, our work shows that recirculating acetate has the potential to boost lactic acid production from waste biomass to levels more attractive for application.}},
  author       = {{Khor, Way Cern and Roume, Hugo and Coma, Marta and Vervaeren, Han and Rabaey, Korneel}},
  issn         = {{0175-7598}},
  journal      = {{APPLIED MICROBIOLOGY AND BIOTECHNOLOGY}},
  keywords     = {{ESCHERICHIA-COLI,Mixed culture,ACETIC-ACID,LACTOBACILLUS-PLANTARUM,GLYCEROL FERMENTATION,ENERGY-CONSERVATION,GROWTH,RUMEN,PH,INHIBITION,COMMUNITY,Lactic acid,Acetate,Lignocellulosic biomass}},
  language     = {{eng}},
  number       = {{19}},
  pages        = {{8337--8348}},
  title        = {{Acetate accumulation enhances mixed culture fermentation of biomass to lactic acid}},
  url          = {{http://dx.doi.org/10.1007/s00253-016-7578-5}},
  volume       = {{100}},
  year         = {{2016}},
}

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