Effect of pH and Neem Extract on Metabolite Content and Bacterial Contaminant of Arthrospira platensis Cultures

Arthrospira platensis is a type of microalgae known as a superfood because it has many benefits in the health and renewable energy sectors. Cultivation of A. platensis as a renewable energy source is carried out in an open pond system. Bacteria, fungi, grazers and other microalgae frequently contaminated the mass culture of A. platensis. Bacteria were the most dominant contaminant in microalgae culture, reaching up to 60. Botanical pesticides are known to reduce contaminants without damaging microalgae cells. This study presents the combined effect of pH and neem (Azadirachta indica) extract on the growth, biomass, pigment, secondary metabolite and bacterial contaminants diversity of A. platensis. The results showed that the optimal conditions for growth and metabolite production in A. platensis were in the pH range of 9–10 with the addition of neem extract. pH 9 + neem extract produced the highest SGR (specific growth rate), density and cell biomass, namely 2.02 × 106 cells/mL, 0.8 g L-1 d-1 and 6.22 g L-1,