Biomass growth was quantified daily, in terms of the optical
density (OD) measured with Beckman DU530 spectrophotometer
(Beckman Coulter Inc., USA) at a wavelength of 750 nm. Ash free
dry weight (AFDW, g L1) for the corresponding OD750 values
were calculated using the following correlation derived for G. sulphuraria
(Selvaratnam et al., 2014b):