Potential assessment of some micro- and macroalgal species for bioethanol and biodiesel production

ABSTRACT

In this study, five macroalgae and four microalgae in addition to seven Cyanophycean, blue-green algae, were isolated from different environmental habitats. The ability of these species for bioethanol and biodiesel production was assessed. Five techniques were examined for cell wall disruption, namely thermic shock, manual grinding, acid, base, and enzymatic digestion. Among these methods, sulfuric acid (3%) achieved the highest reducing sugar yield (%) followed by the enzymatic then the base hydrolysis methods. For each species, the resulted yield of reducing sugars (%) was dependent on the hydrolysis method rather than on the quantity of the total sugars (as mg/100 mg dr weight). After 48 hours of fermentation, Arthrospira platensis, Chlorella marina, and Ulva linza proved to be promising for bioethanol production estimating 45.49%, 23.24%, and 12.01% as ethanol yield, respectively. For all the tested species, grinding followed by enzymatic hydrolysis methods recovered maximum protein amounts (as mg/100 mg dry weight). On the other hand, Caulerpa prolifera, Anabaena variabilis, and Scenedesmus obliquus produced elevated biodiesel quantities of 13.55%, 21.63%, and 28.44% of dry weight, respectively. For each tested species, the quantity of the obtained biodiesel (%) was proportional to the extracted amount of lipids. Gas chromatography–mass spectroscopy (GC-MS) analysis of the produced oil showed dominant composition of saturated fatty acids implying a suitable oil quality. The results of this study recommended large-scale cultivation of A. platensis, C. marina, and U. linza as costless candidates for bioethanol production. The study also validated S. obliquus, A. variabilis, and Caulerpa prolifera as reliable biodiesel producers with an encouraging oil composition ratio for probable commercial applications.

KEYWORDS:

• Arthrospira platensis
• Anabaena variabilis
• Caulerpa prolifera
• fermentation
• carbohydrates
• lipids

Disclosure statement

The authors declare that there is no conflict of interest.

Additional information

Notes on contributors

Mona M. Ismail

Mona M. Ismail is an Associate professor of Phycology, the National Institute of Oceanography and Fisheries, Alexandria, Egypt. Dr. Mona holds aPh.D. from the Faculty of Science, Tanta University, Egypt. She serves as an editorial member and reviewer for many international Journals. Her scientific interest is concerned by the biodiversity of aquatic algae and their biotechnology.

Gehan A. Ismail

Gehan A. Ismail is an  Assistant professor in the Botany Department. Faculty of Science, Tanta University, Tanta, Egypt. She has been teaching students in the field of Phycology, Physiology, and Microbiology since 2006. Her major interest field of research is algal biotechnology through the application of algae in medicine, biofuels, and nanotechnology.

Mostafa M. El-Sheekh

Mostafa M. El-Sheekh is a Professor of Phycology. He has nearly 35 years of experience in research and teaching in the field of algae and its applications. Dr. El-Sheekh served as the Dean Faculty of Science, Tanta University, Egypt, and Cultural counselor in the Egyptian Embassy in Yemen and Uzbekistan and Vice President of Tanta University for Postgraduate Studies and Research. Dr. El-Sheekh holds a Ph.D. in Phycology from Tanta University and Göttingen University, Germany, as a Chanel system fellowship. Notably, Dr. El-Sheekh has authored more than 160 manuscripts, and 8 Book chapters and 2 books.  Dr. El-Sheekh also serves as an editorial member and reviewer for more than 60 peer-reviewed Journals. He published many papers on the production of biodiesel, ethanol, and hydrogen from algae.