A Review of Polyhydroxybutyrate Biosynthesis by Different Microorganisms

Area of Science:

• Biotechnology and Synthetic Biology
• Microbial Engineering
• Sustainable Polymers

Background:

• Polyhydroxybutyrate (PHB) offers a biodegradable alternative to petroleum-based plastics, crucial for mitigating plastic pollution and reducing fossil fuel dependence.
• Existing reviews often focus narrowly on specific microbial genera or metabolic pathways, limiting a holistic understanding of PHB production platforms.
• The need for cost-effective and scalable bioprocesses is paramount for the widespread adoption of PHB.

Purpose of the Study:

• To provide a comprehensive comparative analysis of diverse microbial platforms for Polyhydroxybutyrate (PHB) production.
• To emphasize strategies for strain selection, genetic engineering, and substrate utilization, particularly focusing on waste valorization.
• To evaluate the advantages and limitations of different microbial systems for industrial-scale PHB synthesis.

Main Methods:

• Comparative review of bacterial, yeast, fungal, haloarchaeal, photosynthetic, and mixed microbial culture systems for PHB production.
• Analysis of genetic engineering techniques and strain selection criteria relevant to enhancing PHB yields and productivity.
• Evaluation of substrate flexibility, including the use of waste streams for cost-effective bioprocessing.

Main Results:

• Bacterial systems show efficiency but require costly sterile conditions; engineered yeasts/fungi offer industrial resilience but face metabolic hurdles.
• Haloarchaea provide advantages for non-sterile, high-salinity conditions; photosynthetic microbes integrate CO2 capture but have slow growth rates.
• Mixed microbial cultures are cost-effective using low-cost substrates non-sterilely, though productivity optimization is key.

Conclusions:

• Selecting appropriate microbial platforms and optimizing strain engineering are critical for advancing PHB production.
• Exploring diverse microorganisms, including extremophiles and mixed cultures, enhances substrate flexibility and cost-effectiveness.
• Technoeconomic and life-cycle assessments are essential for establishing PHB as a viable, sustainable solution for the circular economy.