Improvement of ethanol production using green alga Chlorococcum minutum

ABSTRACT

Incessant depletion of fossil fuels urges the governments and non-governmental organizations to invest more on renewable energy sectors including generation of biofuels such as bioethanol. Production of ethanol from algal feedstock has been an interesting area of research in recent times. In the present investigation, feedstock of a green alga Chlorococcum minutum was selected for ethanol production and compared with feedstock of model alga Chlamydomonas reinhardtii. Both the species were grown under in vitro conditions using universal tris-acetate-phosphate (TAP) medium with various concentrations and combinations of vitamins such as thiamin, biotin and cobalamin (B1, B7 and B12) to enhance the biomass in turn reducing sugars in both the algal cultures. Later, these algal feedstocks were used for the production of ethanol under fermentation conditions using yeast. Reducing sugars were more in both the algal cultures grown in Cr3 or Cm3 media (TAP with 0.8 g/L of B1, 0.004 g/L of B7 & 0.004 g/L of B12) and also in Cr2 or Cm2 media (TAP with 0.4 g/L of B1, 0.002 g/L of B7 & 0.002 g/L of B12). In extent, the enhancement of ethanol production was noticed in C. reinhardtii (33.57 g/L) and C. minutum (46.97 g/L) from the feedstocks grown in Cr3 or Cm3 media when compared with feedstocks grown in other vitamin combinations or without vitamin assistance. Specifically, feedstock of C. minutum generated more output at 48 h when compared with model alga. The present work may be useful for the production of ethanol at a commercial level.

GRAPHICAL ABSTRACT

KEYWORDS:

• Chlorococcum
• bioethanol
• vitamins
• reducing sugars
• yeast
• fermentation

Acknowledgements

The authors are thankful to the Department of Science and Technology, Government of India funding in the form of INSPIRE Fellowship to KP. We are also thankful to Prof. Mathivanan, University of Madras, Chennai, India, for C. minutum culture and Dr. L. V. Reddy and Dr. Veda, Department of Microbiology, Yogi Vemana University, Kadapa, India, for providing yeast and valuable suggestions in the work.

Disclosure statement

No potential conflict of interest was reported by the authors.