Expanding the utilization of alkane mixtures: Enhancing medium chain length polyhydroxyalkanoate production in Pseudomonas resinovorans through alkane monooxygenase overexpression

Medium chain length Polyhydroxyalkanoate (mcl-PHA) is a biodegradable bioplastic material with promising applications in various fields, including the medical, packaging, and agricultural industries. This mcl-PHA can be biosynthesized by microorganisms from various carbon sources, and notably, it can also be produced from alkane mixtures contained in pyrolysis oil derived from low-grade waste plastics. In this study, Pseudomonas resinovorans was engineered to overexpress alkane monooxygenase from Lysinibaillus fusiformis JJY0216, enhancing its ability to utilize alkanes as carbon sources and thereby increasing mcl-PHA production. The engineered strain, P. resinovorans JJY01, demonstrated a notable increase in cell dry weight (CDW) to 0.97 g/L and mcl-PHA production to 0.33 g/L from an optimized alkane mixture, achieving a 1.7-fold enhancement compared to the wild type. The PHA content reached 39.5 %, which is 3.1 times higher than the wild type. Further optimization through fed-batch cultivation resulted in P. resinovorans JJY01 achieving 5.65 g/L of CDW, 3.07 g/L of PHA, and a PHA content of 57.5 % within 96 h. In addition, produced mcl-PHA were characterized through various analytical techniques to assess their physical properties and monomer compositions, highlighting the potential of mcl-PHA produced by P. resinovorans JJY01 as a candidate for medical-grade biopolymers.