Production, optimization, scale up and characterization of polyhydoxyalkanoates copolymers utilizing dairy processing...

Area of Science:

• Biotechnology
• Environmental Science
• Polymer Science

Background:

• Petrochemical plastics are non-degradable, posing environmental challenges.
• Microbial biotransformation offers a sustainable route to produce biodegradable polymers.
• Dairy industry waste, such as whey, presents a low-cost feedstock opportunity.

Purpose of the Study:

• To investigate the use of deproteinized whey for polyhydroxyalkanoate (PHA) copolymer production.
• To optimize PHA production using Ralstonia eutropha and identify key process variables.
• To evaluate the feasibility of upscaling PHA production from dairy waste.

Main Methods:

• Screening of microbial strains (Ralstonia eutropha vs. Bacillus megaterium) for PHA production.
• Optimization of process variables (amino acid and tween-80 concentration) using a central composite rotatable design.
• Characterization of produced PHA using ESI-MS, FTIR, and TEM.
• Upscaling PHA production to a 3.0 L bioreactor.

Main Results:

• Ralstonia eutropha demonstrated higher PHA production compared to Bacillus megaterium.
• Optimized conditions (tryptophan 50 mg L⁻¹ and tween-80 3 mL⁻¹) yielded 69.3% polyhydroxybutyrate (PHB) mass fraction, exceeding the predicted 62.8%.
• Enhanced R. eutropha mass gain (6.80 g L⁻¹) and PHB content (4.71 g L⁻¹) were achieved.
• Upscaled production in a 3.0 L bioreactor maintained similar PHA content and yield.

Conclusions:

• Deproteinized whey is a viable and inexpensive feedstock for producing high-content biopolymers (PHA).
• Microbial biotransformation using Ralstonia eutropha offers a sustainable approach to waste management and biopolymer production.
• Optimized bioprocesses can efficiently convert dairy waste into valuable biodegradable materials.