Characterization of Polyhydroxyalkanoates Produced by Contaminated Soil Bacteria using Wastewater and Glucose as Carbon Sources

Purpose: To isolate polyhydroxyalkanoates (PHA)-producing bacterial strains from contaminated soil using industrial wastewater and glucose as carbon sources.
Methods: The strains were isolated and identified as Pseudomonas, Bacillus, Enterobacter, Exiguobacterium and Stenotrophomonas using biochemical tests and further confirmed by Macrogen sequencing. Two different sources, namely, glucose and wastewater were used to evaluate and compare the use of wastewater as a carbon source for PHA production. The biomass obtained was analyzed by Fourier transform infra-red (FTIR) to identify the presence of PHA in it. Afterwards, PHA extraction was carried out and then gas chromatography (GC) performed to identify PHA monomers.
Results: Utilization of glucose resulted in the production of PHB, while wastewater yielded copolymers poly-3 hydroxybutyrate-co-3hydroxyvalerate P(3HB-co-3HV) due to its content of volatile fatty acids such as acetic acid, propionic acid and butyric acid, which led to the production of different types of polymers. The maximum PHA production was 41 ± 0.22 % obtained for Stenotrophomonas (SM03) using 2 % glucose as carbon source while for wastewater, maximum production was achieved by the Pseudomonas strain (SM01).
Conclusion: Wastewater is produced in large quantities daily during various activities and therefore can be used as a cheap carbon source for the production of valuable products such as PHA.

Keywords
Polyhydroxyalkanoates; Wastewater; Glucose; Pseudomonas strain; Stenotrophomonas