Highly efficient production of polyhydroxybutyrate using an open dual one-pot fermentation by Halomonas alkalicola M2

Abstract

The high cost associated with polyhydroxybutyrate (PHB) production demands immediate attention to advance its commercial viability. Herein, we innovatively construct highly efficient production of PHB from low-cost lignocellulosic biomass (LCB) using an open one-pot fermentation by the alkali-halophilic Halomonas alkalicola M2 developed in our previous work. We first develop alkaline pretreatment of LCB to achieve open one-pot fermentation and efficient conversion. Multi-objective optimization of fermentation conditions produces 103.421 mg/L of PHB with a content of 14.437 % and effectively promotes saccharification with cellulose and xylan enzymatic efficiencies of 82.948 % and 73.710 %, respectively. We then develop an open dual one-pot fermentation process, involving the conversion of lignin- and lignin-derived compounds-enriched slurry in the first pot and subsequent polysaccharide conversion in the second pot, to achieve efficient whole LCB components conversion, yielding a record 9.57 g/L of PHB. More importantly, we extend an open dual one-pot-fed-batch fermentation, producing 0.80 g/L of PHB with 27.69 % content in the first pot and 20.08 g/L of PHB with 61.86 % content in the second pot, showing significantly higher than many reported strains. Overall, this work demonstrates the effectiveness of utilizing cheap LCB in a newly designed fermentation process to produce PHB efficiently, representing a significant advancement in this field.