Enhanced production of bioethanol and ultrastructural characteristics of reused Saccharomyces cerevisiae immobilized calcium alginate beads
2011
Lee, Kwang Ho | Choi, In Seong | Kim, Young-Gyu | Yang, Duck-Joo | Bae, Hyeun-Jong
Yeast immobilized on alginate beads produced a higher ethanol yield more rapidly than did free yeast cells under the same batch-fermentation conditions. The optimal fermentation conditions were 30°C, pH 5.0, and 10% initial glucose concentration with 2% sodium alginate beads. The fermentation time using reused alginate beads was 10–14h, whereas fresh beads took 24h, and free cells took 36h. All bead samples resulted in nearly a 100% ethanol yield, whereas the free cells resulted in an 88% yield. Transmission electron microscopy (TEM) showed that the shortened time and higher yield with the reused beads was due to a higher yeast population per bead as well as a higher porosity. The ultrastructure of calcium alginate beads and the alginate matrix structure known as the “egg-box” model were observed using TEM.
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