Isolation of a thermotolerant bacterium producing medium-chain-length polyhydroxyalkanoate

Area of Science:

• Microbiology
• Biotechnology
• Polymer Science

Background:

• Industrial production of polyhydroxyalkanoates (PHAs) is hindered by high costs, particularly substrate and cultivation expenses.
• Developing cost-effective bioplastics requires identifying microorganisms that utilize inexpensive feedstocks and tolerate high-temperature fermentation.

Purpose of the Study:

• To isolate a thermotolerant microorganism capable of producing medium-chain-length (mcl) PHAs.
• To utilize a biodiesel fuel (BDF) by-product as a cost-effective carbon source for PHA synthesis.

Main Methods:

• Isolation and cultivation of thermotolerant microorganisms from BDF by-products.
• Characterization of PHA production using various carbon sources (BDF, acetate, octanoate, dodecanoate) at elevated temperatures.
• Phylogenetic analysis using 16S rRNA gene sequencing to identify the isolated strain.

Main Results:

• A thermotolerant microorganism, designated strain SG4502, was successfully isolated.
• Strain SG4502 accumulates mcl-PHAs from BDF by-products at 45°C and from other carbon sources up to 55°C.
• Phylogenetic analysis identified strain SG4502 as belonging to the genus Pseudomonas, marking the first report of PHA synthesis by a thermotolerant Pseudomonas species.

Conclusions:

• A novel thermotolerant bacterium, strain SG4502, capable of accumulating mcl-PHAs from BDF by-products has been identified.
• This strain's ability to assimilate BDF by-products and produce PHAs at high temperatures presents a significant opportunity for reducing industrial PHA production costs and advancing bioplastic applications.