Time-Course Proteomic Analysis of Pseudomonas putida KT2440 during Mcl-Polyhydroxyalkanoate Synthesis under Nitrogen Deficiency

Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) have gained great attention as a new green alternative to petrochemical-derived polymers. Due to their outstanding material properties they can be used in a wide range of applications. Pseudomonas putida KT2440 is a metabolically versatile producer of mcl-polyhydroxyalkanoates. Although the metabolism of polyhydroxyalkanoate synthesis by this bacterium has been extensively studied, the comparative proteome analysis from three growth stages of Pseudomonas putida KT2440 cultured with oleic acid during mcl-PHA synthesis has not yet been reported. Therefore; the aim of the study was to compare the proteome of Pseudomonas putida KT2440 at different time points of its cultivation using the 2D difference gel electrophoresis (2D-DIGE) technique. The analyses showed that low levels of a nitrogen source were beneficial for mcl-PHA synthesis. Proteomic analysis revealed that the proteins associated with carbon metabolism were affected by nitrogen starvation and mcl-PHA synthesis. Furthermore, the induction of proteins involved in nitrogen metabolism, ribosome synthesis, and transport was observed, which may be the cellular response to stress related to nitrogen deficiency and mcl-PHA content in bacterial cells. To sum up; this study enabled the investigators to acquire a better knowledge of the molecular mechanisms underlying the induction of polyhydroxyalkanoate synthesis and accumulation in Pseudomonas putida KT2440 that could lead to improved strategies for PHAs in industrial production.