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.