Ethanol production from mahula (Madhuca latifolia L.) flowers using free and immobilized (in Luffa cylindrical L. sponge discs) cells of Zymomonas mobilis MTCC 92

Abstract

A novel immobilization method involving Zymomonas mobilis immobilized in a luffa (Luffa cylindrica L.) matrix for ethanol production from mahula (Madhuca latifolia L.) flowers was investigated. The dried spongy fruits of luffa, a cucurbitaceous crop available in abundance in tropical and sub-tropical countries, have been found to be a promising material for immobilizing microbial cells. In our study, the cells not only survived, but they were also active physiologically for four growth cycles, yielding ethanol at 251.1±0.012, 247.9±0.08, 243.4±0.042 and 240.71±0.033 g/kg flowers in the first, second, third, and fourth cycles, respectively, after 96 h fermentation. Ethanol production by the immobilized cells was 9.2% higher than that by free cells. The ethanol yield (Yp/s), volumetric substrate uptake (Qs), and final sugar to ethanol conversion rate (%) obtained with luffa-immobilized cells of Z. mobilis were 0.439±0.004 g/g, 0.994±0.009 g/l/h, and 87.8%, respectively, which were 7.06, 2.62, and 6.92% higher than that of free cells. © Springer-Verlag and the University of Milan 2011.