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Improvement of the Polyhydroxyalkanoates Recovery from Mixed Microbial Cultures Using Sodium Hypochlorite
Gabriela Montiel-Jarillo1, Diego A Morales-Urrea2, Edgardo M Contreras2
1GENOCOV Research Group, Department of Chemical, Biological and Environmental Engineering, School of Engineering, Universitat Autònoma de Barcelona, Escola d'Enginyeria. Edifici Q Campus UAB, Bellaterra, 08193 Barcelona, Spain.
Polymers
|October 14, 2022
Summary
Recovering polyhydroxyalkanoates (PHAs) from mixed microbial cultures is challenging. Dimethyl carbonate (DMC) offers higher recovery efficiency than chloroform (CF) without pre-treatment for PHAs like polyhydroxybutyrate (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV).
Area of Science:
- Biotechnology
- Polymer Science
- Environmental Engineering
Background:
- Polyhydroxyalkanoates (PHAs) are biodegradable polymers with potential applications in various industries.
- Utilizing mixed microbial cultures (MMC) and organic waste streams can significantly reduce PHA production costs.
- Downstream processing, including recovery and purification, remains a major challenge for cost-effective PHA production from MMC.
Purpose of the Study:
- To evaluate the efficiency of polyhydroxyalkanoates (PHAs) recovery from mixed microbial cultures (MMC) using different pre-treatment and extraction methods.
- To compare the efficacy of dimethyl carbonate (DMC) and chloroform (CF) as extraction solvents for PHAs recovery.
- To investigate the impact of sodium hypochlorite (NaClO) pre-treatment on PHA recovery efficiency.
Main Methods:
- Mixed microbial cultures (MMC) were cultivated in a sequencing batch reactor (SBR) using synthetic olive mill wastewater.
- Polyhydroxybutyrate (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were accumulated using acetic acid or acetic/propionic acid as carbon sources.
- Sodium hypochlorite (NaClO) pre-treatment was applied, followed by extraction with dimethyl carbonate (DMC) or chloroform (CF).
- PHA recovery efficiency (RE) was determined, and the obtained polymers were characterized using various analytical techniques (NMR, GPC, DSC, TGA).
Main Results:
- Dimethyl carbonate (DMC) resulted in higher polyhydroxyalkanoates (PHAs) recovery efficiency (RE) compared to chloroform (CF) when no pre-treatment was applied.
- Chloroform (CF) extraction required a sodium hypochlorite (NaClO) pre-treatment step to achieve improved recovery of polyhydroxybutyrate (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV).
- Recovery efficiency (RE) was consistently higher for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) than for polyhydroxybutyrate (PHB) across all tested conditions.
Conclusions:
- Dimethyl carbonate (DMC) is a more efficient solvent for polyhydroxyalkanoates (PHAs) recovery from mixed microbial cultures (MMC) without pre-treatment.
- Sodium hypochlorite (NaClO) pre-treatment is necessary for effective polyhydroxyalkanoates (PHAs) recovery when using chloroform (CF) as an extraction solvent.
- Optimizing downstream processing, particularly solvent selection and pre-treatment, is crucial for the economic viability of PHA production from waste streams.
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