A polyhydroxyalkanoates bioprocess improvement case study based on four fed-batch feeding strategies.

Area of Science:

• Biotechnology
• Microbial Engineering
• Polymer Science

Background:

• Medium chain length polyhydroxyalkanoates (mcl-PHAs) are biodegradable polymers with diverse applications.
• Pseudomonas putida KT2440 is a well-characterized bacterium capable of PHA accumulation.
• Efficient production of mcl-PHAs requires optimized fermentation processes.

Purpose of the Study:

• To model and optimize the production of mcl-PHAs using Pseudomonas putida KT2440.
• To develop and evaluate novel feeding strategies for enhanced PHA yield.
• To investigate the impact of nutrient limitation on PHA content.

Main Methods:

• Development and testing of four novel feeding strategies using a constructed model.
• Implementation of the optimal feeding strategy in pilot-scale fermentations (5L).
• Application of a phosphate starvation strategy to enhance PHA accumulation.
• Scale-up of the optimized process to a 20L bioreactor.

Main Results:

• The optimal feeding strategy achieved a cell dry weight of 70.6 g/L with 38% PHA in 25 hours at 5L scale.
• Phosphate starvation increased PHA content to 56% (94.1 g/L) within 25 hours at 5L scale.
• The process scaled to 20L yielded 91.2 g/L cell dry weight with 65% PHA after 25 hours.

Conclusions:

• Optimized feeding strategies and phosphate starvation are effective for high-yield mcl-PHA production by Pseudomonas putida KT2440.
• The developed process demonstrates successful scalability for industrial mcl-PHA manufacturing.
• This study provides a robust framework for the bioproduction of valuable mcl-PHA polymers.