403 OPTIMIZATION OF BACTERIAL DOSES AND INCUBATION TIME ON ETHANOL FERMENTATION OF NIPAH FOR BIOFUEL ENERGY Wiludjeng Trisasiwi, Ari Asnani and Retna Setyawati Jenderal Soedirman University, Purwokerto, Indonesia Abstract. Nipah ( Nypa frutic ans) is a species of palm trees that grows in mangroves environment near the offshore. Napa is potential to produce biofuel energy. The purposes of this research were 1) to determine the optimum bacterial concentration for fermentation to produce high ethanol, and 2) to determine the optimum incubation time for fermentation to produce high ethanol. The research had been conducted from June until November 2009 used microbe Saccharomyces cerevisiae. This research was an experimental method, factors tested including microbial concentration and incubation time. The variables observed in this research were reduced sugar content, total microbial (cfu/ml), and ethanol yield. The average results showed that the highest ethanol content was produced at a starter concentration of 7.5% which produced 9.55% of ethanol. The highest ethanol content was obtained from the 6 days of incubation time which produced 8.98% of ethanol. Keywords: Biofuel; Concentration; Incubation Time; Nypa frut ic ans; Saccharomyces cerevisiae 1 Introduction The decreasing of fossil energy resources in the world including Indonesia, forcing the energy experts to look for other renewable energy as an alternative to fossil fuels. One type of biofuel that has been developed to replace the gasoline fuel is ethanol (ethyl alcohol), which is made from biomass (plants) through biological processes, namely enzymatic and fermentation. Results from research during the last 20 years has found 60 species of plants that can be used as an alternative to fuel energy, one of which is Nypa frutic ans as raw material for bioethanol. Nipah ( Nypa frutic ans) is a kind of palm that grows on mangrove forest environment or tidal area near the waterfront. This plant is intended to protect land or sea shore from abrasion. Like the coconut tree, whole nipah plant can be used for various purposes. Napa can also be tapped to get sweet liquid from young fruit bunches. So far utilization of nipah sap is not optimal. Communities in the coastal areas used nipah sap for processing sugar, such in the Village Nusadadi, District Sumpiuh, Banyumas Regency [20]. But the sugar obtained has a sense of slightly salty and less preferred by consumers, so that processing of nipah sap into sugar was not optimal. This encourages the utilization of nipah sap to another product of the processing of bio-ethanol. Proceedings of the Third International Conference on Mathematics and Natural Sciences (ICMNS 2010)