The effect of initial medium pH on fungi–algae pellets formation
was further investigated since pH was considered as another
important factor for pellet formation. The pH of culture broth
was adjusted ranged from 4.5 to 7.0 by 1 M H2SO4. It was observed
that the speed of fungi–algae pellet formation was faster in the
medium with lower initial pH value (Table 2b), which further
confirmed our earlier conjecture. In order to confirm that algae
aggregation in this study was not induced or triggered by low
pH, an independent control experiment assessing the effect of lowering
pH on aggregation/pelletization of algal cells in the absence
of fungus was conducted and the results showed that pH-induced
flocculation of microalgae was not observed when the pH of culture
broth was as low as 4.0 without fungi spores addition (Table
2b).