Microalgae-bacteria interaction in palm oil mill effluent treatment

Palm oil mill effluent (POME) contains a substantial amount of nutrients and a significant amount of indigenous microorganisms that consume the nutrients for their growth. In this study, we demonstrated that cultivation of microalgae in POME was able to reduce its carbon and nutrient contents. Three native microalgae isolates, namely, Coelastrella sp. UKM4, Chlamydomonas sp. UKM6 and Scenedesmus sp. UKM9, were cultured in sterilized and unsterilized anaerobic POME to evaluate the microalgae-bacteria interactions for phycoremediation of POME. The results showed higher COD removal in unsterilized POME than in sterilized POME due to microalgae-bacteria consortia interaction. Of the three microalgae isolates, the interaction of Scenedesmus sp. UKM9 with bacteria showed the highest COD and PO43- removal percentages. For NH4+ removal, all three isolates showed removal of more than 80 % in both sterilized and unsterilized POME. Quantitative real-time polymerase chain reaction analysis showed that the quantities of bacteria were constant after the treatment, while the quantities of microalgae changed. Metagenomics analysis showed that the community of bacteria shifted after microalgae cultivation in POME, with Actinobacteria, Bacteroidetes, Planctomycetes and Proteobacteria being the major phyla.