The wavelength of 686 nm (OD686) was selected for MA cell
density determination based on the recorded absorbance peak
through the spectrum analysis which was performed in the range
of 350 nme1100 nm. Due to the pure cultivation of MA, Chlorella
sp., obvious absorbance peak could be observed showing that the
biomass consisted of mono-specific species of microalgae.
Whereas, the measurement of optical density for EM was performed at the wavelength of 600 nm (OD600) as this methodology
had been a central technique in bacteria density determination
in microbiology (Contois, 1959; Widdel, 2007). The
standardization of the optical density on microbial cell density was
carried out by forming a standard regression curve. OD measurement
of bacterial cultures such as EM is a common technique used
in microbiology and applicable to MA due to its small cell size.