Nutritional factors influence polyhydroxybutyrate in microalgae growing on palm oil mill effluent

Bioplastic made of microalgae is attractive since it does not consume high amounts of substrate compared to bacteria. However, to make the production more feasible, growth needs to be done in wastewater to replace the commercial medium. This research was done to study the ability of microalgae growing on palm oil mill effluent (POME) to produce a bioplastic, polyhydroxybutirate (PHB). The experiment was conducted in a three step approach: (i) screening the microalgae strain, (ii) investigating a different kind of organic carbon source, and (iii) investigating the interactive effect of Fe-EDTA, POME fractions, and organic carbon concentrations. Results showed that Botryococcus braunii produced the highest PHB content compared to Arthrospira platensis and Haematococcus pluvialis. Glucose and glycerol stimulated the PHB productivity up to 20 mg L day. The interaction of glycerol-POME and glycerol Fe-EDTA influenced the growth. For PHB accumulation, no interaction between factors was found. The optimal condition to obtain 33% PHB was found on 50% POME supplemented with high glycerol and high Fe-EDTA concentration.