Application of palm pressed fiber as a carrier for ethanol production by Candida shehatae TISTR5843

palm pressed fiber (ppf) is a clean and renewable lignocellulosic material. the ppf and delignified ppf (dppf) were used as a carrier for immobilization of candida shehatae tistr5843 in bioethanol production. ppf was pre-treated by milling to obtain small particles, whereas dppf was the delignification of ppf using naclo2. c. shehatae tistr5843 was grown in modified yeast extract- malt (ym) medium at 30 ± 2oc on an orbital shaker at 150 rpm for batch and repeated batch fermentation. in the batch system, immobilized cells on a small size, less than 0.5 mm, of dppf (sdppf) gave the maximum ethanol production of 11.5 g l-1 at 24 hrs cultivation period. the ethanol concentration and ethanol yield of sdppf were 6.2% and 6.8% higher (ethanol production 11.5 g l-1, ethanol yield 0.47 g g-1) than those of free cells (ethanol production 10.8 g l-1, ethanol yield 0.44 g g-1) after 36 hrs of cultivation. in contrast, the small size of ppf (sppf) was selected as a carrier in repeated batch fermentation for cost effectiveness. the ethanol productivity of immobilized yeast cells in repeated batch fermentations was 45.2-51.6% greater than that obtained from batch fermentations. the immobilized cells on sppf improved the ethanol production and could be reused 4 times with retaining the activity of 93%. in conclusion, ppf is a potential carrier in the immobilization system. the pre-treatment of ppf increases the surface area that enhances cell adsorption and ethanol production by c. shehatae tistr5843.