Effect of oxygen mass transfer rate on the production of 2,3-butanediol from glucose and agro-industrial byproducts by Bacillus licheniformis ATCC9789

Autor: Stefano Rebecchi, Davide Pinelli, Giulio Zanaroli, Fabio Fava, Dario Frascari
Jazyk: angličtina
Rok vydání: 2018
Předmět:
Zdroj: Biotechnology for Biofuels, Vol 11, Iss 1, Pp 1-14 (2018)
Druh dokumentu: article
ISSN: 1754-6834
DOI: 10.1186/s13068-018-1138-4
Popis: Abstract Background 2,3-Butanediol (BD) is a largely used fossil-based platform chemical. The yield and productivity of bio-based BD fermentative production must be increased and cheaper substrates need to be identified, to make bio-based BD production more competitive. As BD bioproduction occurs under microaerobic conditions, a fine tuning and control of the oxygen transfer rate (OTR) is crucial to maximize BD yield and productivity. Very few studies on BD bioproduction focused on the use of non-pathogenic microorganisms and of byproducts as substrate. The goal of this work was to optimize BD bioproduction by the non-pathogenic strain Bacillus licheniformis ATCC9789 by (i) identifying the ranges of volumetric and biomass-specific OTR that maximize BD yield and productivity using standard sugar and protein sources, and (ii) performing a preliminary evaluation of the variation in process performances and cost resulting from the replacement of glucose with molasses, and beef extract/peptone with chicken meat and bone meal, a byproduct of the meat production industry. Results OTR optimization with an expensive, standard medium containing glucose, beef extract and peptone revealed that OTRs in the 7–15 mmol/L/h range lead to an optimal BD yield (0.43 ± 0.03 g/g) and productivity (0.91 ± 0.05 g/L/h). The corresponding optimal range of biomass-specific OTR was equal to 1.4–7.9 $${\text{mmol}}_{{{\text{O}}_{2} }} /{\text{g}}_{\text{CDW}} /{\text{h}}$$ mmolO2/gCDW/h , whereas the respiratory quotient ranged from 1.8 to 2.5. The switch to an agro-industrial byproduct-based medium containing chicken meat and bone meal and molasses led to a 50% decrease in both BD yield and productivity. A preliminary economic analysis indicated that the use of the byproduct-based medium can reduce by about 45% the BD production cost. Conclusions A procedure for OTR optimization was developed and implemented, leading to the identification of a range of biomass-specific OTR and respiratory quotient to be used for the scale-up and control of BD bioproduction by Bacillus licheniformis. The switch to a byproduct-based medium led to a relevant decrease in BD production cost. Further research is needed to optimize the process of BD bioproduction from the tested byproduct-based medium.
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