Influence of Growth Media on PHA production: A Study on Coconut Rhizosphere soil Bacteria in Minimal salt Media and Tender Coconut Water

Abstract— The study aims to compare the extraction of polyhydroxyalkanoates (PHA), accumulated as intracellular inclusions in rhizosphere bacteria, when cultivated in minimal salt medium (MSM) and tender coconut water (TCW). Soil samples were collected from beneath a coconut tree, and bacterial isolates were obtained. The presence of PHA-producing bacteria was initially screened using Sudan Black B staining and subsequently confirmed with Nile Blue A staining. The confirmed PHA-producing isolates were cultured in MSM (designated as Sample A) and in TCW (designated as Sample B). PHA were successfully extracted from both media. Biofilm formation was observed, and PHA quantification was carried out using the crotonic acid assay. In addition, antioxidant activity was evaluated using the DPPH assay. This investigation provides a comparative assessment of PHA production by coconut rhizosphere bacteria grown in MSM and TCW, highlighting the potential of tender coconut water as a sustainable raw material for large-scale PHA production.