Microbial production of 2,3-butanediol through a two-stage pH and agitation strategy in 150 l bioreactor

•Isolation of Enterobacter cloacae for 2,3 BD production.•Optimization of process parameters (pH, temperature, agitation).•Residual fed-batch strategy with commercial grade glucose.•Two-stage pH and agitation in 150 l bioreactor.•Total production of 85 g/l of 2,3 BD with 96% theoretical yield.

This study was focused on scaling up of 2,3-butanediol (2,3-BD) production, via fermentation in a 150 l bioreactor using the newly isolated strain Enterobacter cloacae TERI BD 18. Operational parameters were customized for the strain E. cloacae using a fed- batch strategy, which enhanced the glucose to 2,3-BD conversion yield (0.44 g/g). Furthermore, dual stage pH and agitation control regime was considered where in the initial 10 h the pH value was 7.5 and the agitation rate used was 200 rpm favoring bacterial growth, while these values were subsequently changed to a pH value of 6.5 and an agitation rate of 150 rpm leading to enhanced accumulation of 2,3-BD. Production of 85 g/l of 2,3-BD was achieved with ethanol and acetoin as the only by-products. Total productivity of 1.73 g/l/h with a yield of 0.48 g of 2,3-BD per g of glucose was achieved in the 150 l bioreactor. Additionally, the total fermentation time was reduced to 50 h with this strategy. The integrated approach of fed-batch strategy together with dual regime in pH and agitation control favors 2,3-BD production in the pilot scale bioreactor system employed in this study.

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