Polyhydroxyalkanoate production from whey by Pseudomonas hydrogenovora

Area of Science:

• Biotechnology and Industrial Microbiology
• Polymer Science
• Sustainable Bioprocessing

Background:

• Whey permeate, a dairy industry byproduct, contains lactose, a potential carbon source.
• Polyhydroxyalkanoates (PHAs) are biodegradable polymers with diverse applications.
• Efficient microbial production of PHAs from low-cost substrates is crucial for economic viability.

Purpose of the Study:

• To evaluate the enzymatic hydrolysis of whey permeate for producing poly-3-hydroxybutyric acid (PHB).
• To compare the efficacy of hydrolyzed whey permeate against pure glucose and galactose for bacterial growth and PHB production.
• To investigate the biosynthesis of PHA co-polyesters using hydrolyzed whey permeate and valerate.

Main Methods:

• Enzymatic hydrolysis of lactose in whey permeate to glucose and galactose.
• Cultivation of *Pseudomonas hydrogenovora* using hydrolyzed whey permeate and pure sugars.
• Fermentation in shaking flasks and bioreactors under controlled conditions (nitrogen limitation, co-feeding).
• Determination of kinetic parameters, molecular mass distribution, and thermal properties of produced PHAs.

Main Results:

• Hydrolyzed whey permeate was a more advantageous substrate than pure glucose or galactose for PHB production.
• Fermentation with hydrolyzed whey permeate yielded a maximum PHB concentration of 1.27 g/l.
• Co-feeding valerate resulted in the production of poly-(3HB-co-21%-3HV) with a maximum concentration of 1.44 g/l and altered molecular characteristics.

Conclusions:

• Enzymatically hydrolyzed whey permeate is a cost-effective and efficient substrate for microbial PHA production.
• The process allows for the tailored synthesis of PHA co-polyesters by incorporating specific precursors like valerate.
• This study demonstrates a sustainable approach to valorizing dairy industry waste for biopolymer manufacturing.