High‐titer n‐butanol production by clostridium acetobutylicum JB200 in fed‐batch fermentation with intermittent gas stripping

Abstract

Acetone-butanol-ethanol (ABE) fermentation with a hyper-butanol producing Clostridium acetobutylicum JB200 was studied for its potential to produce a high titer of butanol that can be readily recovered with gas stripping. In batch fermentation without gas stripping, a final butanol concentration of 19.1 g/L was produced from 86.4 g/L glucose consumed in 78 h, and butanol productivity and yield were 0.24 g/L h and 0.21 g/g, respectively. In contrast, when gas stripping was applied intermittently in fed-batch fermentation, 172 g/L ABE (113.3 g/L butanol, 49.2 g/L acetone, 9.7 g/L ethanol) were produced from 474.9 g/L glucose in six feeding cycles over 326 h. The overall productivity and yield were 0.53 g/L h and 0.36 g/g for ABE and 0.35 g/L h and 0.24 g/g for butanol, respectively. The higher productivity was attributed to the reduced butanol concentration in the fermentation broth by gas stripping that alleviated butanol inhibition, whereas the increased butanol yield could be attributed to the reduced acids accumulation as most acids produced in acidogenesis were reassimilated by cells for ABE production. The intermittent gas stripping produced a highly concentrated condensate containing 195.9 g/L ABE or 150.5 g/L butanol that far exceeded butanol solubility in water. After liquid-liquid demixing or phase separation, a final product containing ~610 g/L butanol, ~40 g/L acetone, ~10 g/L ethanol, and no acids was obtained. Compared to conventional ABE fermentation, the fed-batch fermentation with intermittent gas stripping has the potential to reduce at least 90% of energy consumption and water usage in n-butanol production from glucose.

Integrated processing for the separation of biobutanol. Part A: experimental investigation and process modelling

“…Nevertheless, it must be mentioned that gas stripping can be realised easily and that the continuous butanol removal increases the productivity [ 39 ]. Gas stripping was successfully operated in combination with batch [ 40 ], fedbatch [ 41 ], continuous [ 42 ] and fluidised bed reactors [ 43 ].…”

Reexamination of the Physiological Role of PykA in Escherichia coli Revealed that It Negatively Regulates the Intracellular ATP Levels under Anaerobic Conditions

“…In addition, the low energy level due to the absence of oxidative phosphorylation often leads to a higher glycolysis rate, resulting in higher productivity (6). However, as the available ATP in anaerobic fermentation can be generated only from substrate-level phosphorylation, the biomass concentration in anaerobic fermentation is usually much lower than that in aerobic fermentation (2,7). Although a lower energy charge in anaerobic fermentation is beneficial for increasing the glycolysis rate (8)(9)(10), it has been shown that increasing the ATP concentration can improve protein synthesis and increase biomass flux during anaerobic fermentation (11,12).…”

Continuous Acetone–Butanol–Ethanol (ABE) Fermentation with in Situ Solvent Recovery by Silicalite-1 Filled PDMS/PAN Composite Membrane

“…Such a highly concentrated butanol solution would significantly reduce the energy consumption required in final product recovery by distillation. 5,6 The aqueous phase contained 160.7 g/L ABE with 89.6 g/L butanol, which could be further concentrated by a second-stage PV system. 23 Productivity, yield, glucose utilization rates, and conversions achieved under the three dilution rates for a long period of continuous operation are presented in Figure 7.…”

“…5 It is generally believed that integrating the fermentation with the product separation process by using a suitable in situ product recovery (ISPR) technique could overcome the shortage of low solvent (ABE) resistance of these strains. To date, various techniques, such as gas-stripping, pervaporation (PV), liquid−liquid extraction, and adsorption, 6 have been investigated to reduce the effect of butanol inhibition, and enhance solvent productivity and sugar utilization. Among those techniques, PV is considered to be the most promising technique because of its energy efficiency, cost effectiveness, as well as no harmful effects on the microorganisms.…”