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Extensive usage of nonrenewable fossil fuels has urged the community to look into alternate renewable energy such as biofuels. The production of biofuels, including bioethanol, biohydrogen, biodiesel, etc., from crop plants again leads to food insecurity. Hence, the usage of algae, particularly green algae, is the best alternatives to generate biofuels. In the present study, the effects of various factors involved in algal growth in turn bioethanol and biohydrogen production levels were established by choosing green alga Chlamydomonas reinhardtii. Specifically, we crosschecked the effect of heavy metal Cobalt (Co), sodium bicarbonate, and Tris-acetate-phosphate (TAP) medium without Tris base on growth and biofuel production from C. reinhardtii under in vitro conditions. In the current work, 0.2 mg/l Co in TAP medium enhanced the growth and biomass in C. reinhardtii cultures. Furthermore, ethanol production levels were improved in feedstocks grown in TAP medium with 2.0 mg/l sodium bicarbonate. In another experiment, hydrogen production was high in full TAP medium with Tris (trisaminomethane) base when compared to TAP without Tris base. In conclusion, this work may be useful to improve the biomass and biofuel production in green algae.

The present investigation aims to know the effects of oxygen scavengers such as sodium sulfite (Na 2 SO 3 ), sodium bisulfite (NaHSO 3 ), sodium dithionite (Na 2 S 2 O 4 ), and sodium metabisulfite (Na 2 S 2 O 5 ) on growth and accumulation of biomass (chlorophylls) in green alga Asterarcys quadricellulare (A. quadricellulare). Alga is grown in tris-acetatephosphate (TAP) medium, along with various concentrations of NaHSO 3 , Na 2 SO 3 , Na 2 S 2 O 4 , and Na 2 S 2 O 5 individually under in vitro conditions. To evaluate the effects of scavengers, in vitro grown algal cells were used to estimate the chlorophyll a and b, along with total chlorophylls. Augmented growth and total chlorophyll content (63.23 mg/L) was noticed in A. quadricellulare cultures grown in TAP with 3.2 mM of sodium sulfite medium. TAP with 0.4 mM sodium bisulfite medium enhanced the growth and total chlorophyll content (49.38 mg/L) in this alga. Similarly, improved growth and total chlorophyll content (44.46 mg/L) was observed in A. quadricellulare grown in TAP with 0.4 mM of sodium dithionite medium. TAP with 0.08 mM sodium metabisulfite medium augmented the growth and total chlorophyll content (41.01 mg/L) in this alga. Higher doses of scavengers inhibit the growth and reduced the total chlorophyll contents in A. quadricellulare. The present work will be helpful to standardize the oxygen scavenger resistance levels in various algal species for anaerobic experiments including in vitro production of hydrogen.