Microalgae consist of different types of carbohydrates which are
mostly stored in the cell wall. Therefore, disruption of microalgal
cell walls is necessary to release the entrapped carbohydrates for
fermentation process. Harun and Danquah [71] observed that the
bioethanol yield of 7.20 g L1 was achieved when the
pre-treatment step was performed with 15 g L1 of microalgae at
140 C using 1% (v/v) of sulfuric acid for 30 min. In this study, fermentation
was completely stopped at 120 h and 72% theoretical
yield of ethanol was achieved. Similarly, Costa et al. [72] studied
about the fermentation time on conversion of bioethanol from
microalgal biomass and observed that 5 days fermentation time
supported maximum yield and recovery of bioethanol. Acid pretreatment
provides an advantage to reduce the cost and energy consumption compared to other methods. This present investigation
concluded that the native isolate of S. bijugatus had significant
quantities of lipids and carbohydrates in its biomass (Table 5)
which can be converted to sustainable biofuels such as biodiesel
and bioethanol.