Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XXI
Written by Ratu SAFITRI, Mia MIRANTI, Ismi Dwi ASTUTI, Lien KARTIAWATI, Jetty NURHAYATI

Immobilization of cells is a method for placing the microbial cells on a carrier material, wherein the catalytic activity of the cells is still high after storage for a long periode of time. The purpose of this study was to determine the optimum formula for the carrier material inoculum for bioethanol fermentation. The carrier material tested were based on different combination of wheat flour: rice flour, tapioca starch: corn starch and alginate. The study consisted of three phases: First phase is the preparation of the encapsulation of Zymomonas mobilis, Kluyveromyces marxianus, and Saccharomyces cerevisiae. The Second phase is the enzyme hydrolysis process and the third is fermentation of the hydrolysate into bioethanol by the consortium on the best carrier. The method used in this research is descriptive and experimental. Descriptive method carried out in the second phase. While the experimental method with completely randomized design is used in the research phase I and III. The consortium used were KI (Z.mobilis and S.cerevisiae), K2 (Z. mobilis and K marxianus), and K3 (Z. mobilis, S.cerevisiae and K. marxianus). The data were statistically analyzed by ANOVA, and followed by Duncan Test in 5% significance level. The results showed that S.cerevisiae and K.marxianus on formula with a combination of wheat flour: rice flour is the best carrier material with cell density about 3,719x1010 CFU / ml and 3,027x1010 CFU / ml. Meanwhile, alginate is the best carrier for Z.mobilis with cell density about 3,576x1010 CFU / ml. Best consortium in the process of bioethanol fermentation from cellulose waste is Z.mobilis and S.cerevisiae (K1), which have the highest ethanol concentration about 7.167%, the efficiency of fermentation about 61.2%, specific growth rate of 0,072 cells / hour, ethanol yield (Yp/s) 0,23 g/g, microbial yield (Yx/s) 0,33 g/g and a maximum ethanol productivity (qp) of 0,58 g/g/h.

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