Potential sustained production of polyhydroxyalkanoate copolymers using cyanobacteria microbiomes

Area of Science:

• Biotechnology
• Microbiology
• Polymer Science

Background:

• Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a promising bioplastic with superior properties to poly(3-hydroxybutyrate) (PHB).
• Cyanobacteria offer a sustainable platform for biopolymer production.
• Previous PHBV production studies often used sterile, small-scale, and short-term methods with isolated strains.

Purpose of the Study:

• To develop a scalable, non-sterile method for PHBV production using cyanobacterial microbiomes.
• To investigate sustained, semi-continuous PHBV production over an extended period.
• To optimize valerate supplementation for enhanced PHBV yield and microbial metabolism.

Main Methods:

• Utilized a semi-continuous cultivation of Synechocystis sp. and Synechococcus sp. microbiomes over 56 days.
• Supplemented with valerate as an external carbon precursor in a 2.5 L working volume.
• Conducted four independent production and recovery repetitions, employing fluorescence microscopy for PHBV visualization.

Main Results:

• Achieved maximum PHBV content of 10.7% dry cell weight with 57.4% 3-hydroxyvalerate (HV) monomer proportion.
• Demonstrated successful PHBV biosynthesis in non-sterile cyanobacterial microbiomes.
• Identified optimal valerate dosage is critical, as excessive amounts inhibited biomass and nitrogen assimilation; Synechococcus sp. produced larger PHBV granules than Synechocystis sp.

Conclusions:

• Established a feasible, scalable, and eco-friendly biomanufacturing platform for sustained PHBV production.
• Highlighted the potential of cyanobacterial microbiomes for industrial bioplastic synthesis.
• Emphasized the importance of metabolic balancing through optimized precursor feeding for efficient biopolymer yield.