Abstract
Pseudomonas putida KT2440, one of the best characterized pseudomonads, is a metabolically versatile producer of medium-chain-length polyhydroxyalkanoates (mcl-PHAs) that serves as a model bacterium for molecular studies. The synthesis of mcl-PHAs is of great interest due to their commercial potential. Carbon and phosphorus are the essential nutrients for growth and their limitation can trigger mcl-PHAs’ production in microorganisms. However, the specific molecular mechanisms that drive this synthesis in Pseudomonas species under unfavorable growth conditions remain poorly understood. Therefore, the proteomic responses of Pseudomonas putida KT2440 to the limited carbon and phosphorus levels in the different growth phases during mcl-PHAs synthesis were investigated. The data indicated that biopolymers’ production was associated with the cell growth of P. putida KT2440 under carbon- and phosphorus-limiting conditions. The protein expression pattern changed during mcl-PHAs synthesis and accumulation, and during the different physiological states of the microorganism. The data suggested that the majority of metabolic activities ceased under carbon and phosphorus limitation. The abundance of polyhydroxyalkanoate granule-associated protein (PhaF) involved in PHA synthesis increased significantly at 24 and 48 h of the cultivations. The activation of proteins belonging to the phosphate regulon was also detected. Moreover, these results indicated changes in the protein profiles related to amino acids metabolism, replication, transcription, translation, stress response mechanisms, transport or signal transduction. The presented data allowed the investigation of time-course proteome alterations in response to carbon and phosphorus limitation, and PHAs synthesis. This study provided information about proteins that can be potential targets in improving the efficiency of mcl-PHAs synthesis.
Highlights
Polyhydroxyalkanoates (PHAs) have attracted much attention in recent years due to their potential to replace petroleum-based polymers
This study demonstrated the cellular responses of Pseudomonas putida KT2440 to dual carbon-phosphorus limitation at the proteomic level
The majority of proteins involved in carbon and energy metabolism were downregulated in the late stationary phase when mcl-PHAs were not synthesized, suggesting that most of the metabolic activities were ceased in the bacterial cells under carbon- and phosphorus-limiting conditions
Summary
Polyhydroxyalkanoates (PHAs) have attracted much attention in recent years due to their potential to replace petroleum-based polymers. PHAs. PHAs are mainly accumulated intracellularly as a storage material for carbon and energy when essential nutrients are in limiting concentrations. The suitability of a bacterium for PHA production depends on many different factors, such as the safety of the organism, achievable cell densities, and the amount, composition, extractability, and properties of accumulated PHAs. PHA monomers produced by microorganisms are classified into three groups: Short chain length (scl-PHA), which consists of monomers containing 4 to 5 carbon atoms, medium chain length (mcl-PHA) containing 6 to 14 carbon. Mcl-PHAs are mainly synthesized and accumulated by Pseudomonas species and are a subject of interest because of their improved properties when compared with scl-PHAs. In particular, mcl-PHAs are mainly synthesized and accumulated by Pseudomonas species and are a subject of interest because of their improved properties when compared with scl-PHAs Due to these properties, mcl-PHAs are promising materials in various fields, especially in biomedical applications, such as tissue engineering and drug delivery [2]
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