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bioRxiv · 10.1101/2021.03.23.436570

Effect of Inoculum Pretreatment on Alcohol Production from Volatile Fatty Acids through an Anaerobic Solventogenic Process

Mockaitis, G.·Bruant, G.·Foresti, E.·Zaiat, M.·Guiot, S. R.
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Abstract

1This work evaluates four different physicochemical pretreatments (acidic, thermal, acidic-thermal and thermal-acidic) on an anaerobic inoculum used for alcohol production from acetate and butyrate. All experiments were conducted in single batches using acetate and butyrate as substrates at 30 {degrees}C and with a pressurized headspace of pure H2 at 2.15 atm (218.2 MPa). Thermal and acidic-thermal pretreatments lead to higher production of both ethanol and butanol. Mathematical modelling shows that the highest attainable concentrations of ethanol and butanol produced were 122 mg L-1 and 97 mg L-1 for the thermal pretreatment (after 17.5 days) and 87 mg L-1 and 143 mg L-1 for the acidic-thermal pretreatment (after 18.9 days). Acetate was produced in all assays. Thermodynamic data indicated that a high H2 partial pressure favoured solventogenic metabolic pathways. Finally, sequencing data showed that both thermal and acidic-thermal pretreatments selected mainly the bacterial genera Pseudomonas, Brevundimonas and Clostridium. The acidic-thermal pretreatment selected a bacterial community more adapted to the conversion of acetate and butyrate into ethanol and butanol, respectively. Thermal-acidic pretreatment was unstable, showing significant variability between replicates. Acidic pretreatment showed the lowest alcohol production.

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Mockaitis, G., Bruant, G., Foresti, E., Zaiat, M., Guiot, S. R.. 2021-03-25. Effect of Inoculum Pretreatment on Alcohol Production from Volatile Fatty Acids through an Anaerobic Solventogenic Process. https://doi.org/10.1101/2021.03.23.436570

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