(R)−3-hydroxybutyrate production by Burkholderia cepacia in the cathode chamber of ethanol-producing microbial fuel cells

In this study, the microbial fuel cell system realized the integrated production of (R)− 3-hydroxybutyrate, ethanol, and electricity. The cathodic chamber could provide a suitable microaerophilic environment, thereby providing favorable oxygen limiting conditions for the accumulation of (R)− 3-HB. In the cathodic chamber, Burkholderia cepacia achieved the production of 26.58 g/L (R)− 3-hydroxybutyrate during a fermentation period of 168 h. Corresponding to the production period of (R)− 3-hydroxybutyrate, the ethanol production by Saccharomyces cerevisiae carried out in the anode chamber reached 25.85, 27.01, and 26.03 g/L, respectively, during the three batches of 56-hour fermentation periods. This microbial fuel cell system also achieved stable power generation for three cycles. The voltages reached 271 mV, 279 mV, and 274 mV with an external resistance of 1000 Ω, respectively. The production of (R)− 3-hydroxybutyrate by Burkholderia cepacia relies on strict fermentation conditions. Of particular concern, its fermentation performance has a high sensitivity to pH value. In addition, the presence of heavy metal ions and the ratio of sugars also significantly affected the production of (R)− 3-hydroxybutyrate. The gradient pre-adaptation can effectively improve (R)− 3-hydroxybutyrate production by Burkholderia cepacia from synthetic lignocellulose hydrolysates. [Display omitted] •The MFC system achieves the co-production of (R)− 3-HB, ethanol, and electricity.•The production of (R)− 3-HB by B. cepacia is sensitive to pH values.•A microaerophilic environment favors the accumulation of (R)− 3-HB.•The addition of Mn2+ and Zn2+ can promote the production of (R)− 3-HB by B. cepacia.•Pre-adaptation promoted the (R)− 3-HB production from lignocellulose hydrolysate.