Optimization of medium‐chain‐length polyhydroxyalkanoate production by Pseudomonas putida KT2440 from co‐metabolism of glycerol and octanoate

Abstract

AbstractIn this study, the co‐metabolism of glycerol and octanoate by Pseudomonas putida KT2440 significantly increased the production of medium‐chain‐length polyhydroxyalkanoate (mcl‐PHA). This was achieved through optimization of various parameters such as substrate concentration, nitrogen concentration, and other mixing conditions related to dissolved oxygen level. Experiments were performed in shake flasks and 5 L fermenter with findings assessed through single factor analysis and response surface methodology. The optimal concentration of substrates to improve mcl‐PHA production were determined to be 40 g glycerol/L, 12.23 g octanoate/L, and 1 g (NH4)2SO4/L. Indirect regulation of dissolved oxygen was achieved by controlling the mixing conditions such as the initial medium volume (50 mL) (shake flask experiment), agitation speed (500 rpm), and aeration rate (10 L/minutes) (fermenter experiment). Optimized process parameters resulted in an mcl‐PHA titer of 8.47 g/L, which was significantly higher than that observed under un‐optimized conditions (3.95 g/L). The response surface method can be efficiently used to determine the optimal level of several factors related to mcl‐PHA production.