Producing poly-3-hydroxybutyrate with a high molecular mass from methane.

Area of Science:

• Microbial biotechnology
• Biopolymer production
• Sustainable chemistry

Background:

• Poly-3-hydroxybutyrate (PHB) is a biodegradable polyester with diverse applications.
• Methane, an abundant and inexpensive carbon source, is a potential substrate for biopolymer synthesis.
• Methanotrophic bacteria offer a route for converting methane into valuable products like PHB.

Purpose of the Study:

• To investigate the potential of methane as a carbon source for PHB production using the methanotrophic strain Methylocystis sp. GB 25.
• To optimize PHB accumulation in a non-sterile bioreactor system.
• To evaluate the yield, efficiency, and quality of PHB produced.

Main Methods:

• Cultivation of Methylocystis sp. GB 25 in 7-l and 70-l pressure bioreactors.
• Two-stage cultivation: continuous growth phase followed by nutrient-deficient batch phase for PHB accumulation.
• Analysis of PHB content, yield, and molecular mass.

Main Results:

• Methylocystis sp. GB 25 accumulated PHB up to 51% of biomass in a non-sterile process.
• Highest PHB production efficiency was observed within the first 5 hours of the accumulation phase.
• Maximum PHB yield was 0.55 g/g of methane consumed, with high molecular mass (up to 2.5x10^6 Da).

Conclusions:

• Methane is a viable and efficient substrate for producing high-quality PHB using Methylocystis sp. GB 25.
• The two-stage cultivation strategy effectively enhances PHB accumulation.
• This process offers a sustainable route for biopolymer production from a readily available resource.