Scale Up Studies for Polyhydroxyalkanoate Production by a Bacillus flexus Strain with Industrial Potential

Area of Science:

• Biotechnology
• Microbial Fermentation
• Polymer Science

Background:

• Polyhydroxyalkanoates (PHA) are biodegradable polymers synthesized by microorganisms.
• Bacterial PHA production is influenced by growth conditions such as nutrient availability and aeration.
• Diverse PHA compositions offer varied material properties.

Purpose of the Study:

• To devise and optimize a bioprocess for PHA production using an indigenous bacterial strain, *Bacillus flexus* MTCC 12841.
• To enhance PHA yield and biomass concentration at a laboratory fermentor scale.
• To characterize the produced PHA polymer and identify its composition.

Main Methods:

• Isolation and cultivation of *Bacillus flexus* MTCC 12841.
• Optimization of fermentation parameters including aeration, agitation, temperature, nutrient feeding, and C:N ratio.
• Gas Chromatography-Mass Spectrometry (GC-MS) for polymer characterization.

Main Results:

• Optimized fermentation achieved a 59% increase in PHA production, reaching 9.73 g/L.
• Biomass concentration increased by 126% to 15.70 g/L.
• The bacterium naturally produced poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) without precursor addition.

Conclusions:

• The optimized bioprocess significantly enhanced PHA production in *Bacillus flexus*.
• The strain's inherent ability to produce PHBV offers a novel pathway for biopolymer synthesis.
• Further optimization could increase PHA yield and the proportion of hydroxyvalerate in the copolymer.