M.J. Hessami - Institute of Biological Sciences, Faculty of Sciences, University of Malaya, KL ۵۰۶۰۳, Malaysia
A. Salleh - Institute of Biological Sciences, Faculty of Sciences, University of Malaya, KL ۵۰۶۰۳, Malaysia
S.M. Phang - Institute of Biological Sciences, Faculty of Sciences, University of Malaya, KL ۵۰۶۰۳, Malaysia

The two red seaweeds, Gracilaria manilaensis and Kappaphycus alvarezii are cultivated in Malaysia for producing agar and carrageenan, respectively. The residues of these seaweeds after removing agar and carrageenan by dilute acid treatment were subjected to enzymatic hydrolysis using cellulase (Cellic CTec ۲). In the optimization of enzymatic hydrolysis, highest glucose concentration was achieved in the sample with liquid: residue ratio of ۷.۵:۱ and enzyme loading of ۱۰ % w w-۱ residue. The resulting glucose was converted to bioethanol using Saccharomyces cerevisiae where bioethanol yields from G. manilaensis and K. alvarezii were ۵۶.۲۶±۱.۱۰ g L-۱ and ۵۱.۱۰±۱.۲۱ g L-۱, respectively, which corresponded to ۹۱ % and ۹۵ % of the theoretical yield. The results of this study indicate that the residues of these seaweeds can be efficiently converted to bioethanol and besides environmental benefits, additional profit can be achieved in the phycocolloid industry.

Bioethanol, Cellulase, Agar residues, Gracilaria manilaensis, Kappaphycus alvarezii