A new local strain of S. cerevisiae F-514, for ethanol production during hot summer season, using Egyptian sugar cane molasses was applied in Egyptian distillery factory. The inouluum was propagated through 300？L, 3？m3, and 12？m3 fermenters charged with diluted sugar cane molasses containing 4%-5% sugars. The yeast was applied in fermentation vessels 65？m3 working volume to study the varying concentrations of urea, DAP, orthophosphoric acid (OPA), and its combinations as well as magnesium sulfate and inoculum size. The fermenter was allowed to stay for a period of 20 hours to give time for maximum conversion of sugars into ethanol. S. cerevisiae F-514 at molasses sugar level of 18%？(w/v), inoculum size of 20%？(v/v) cell concentration of /mL, and combinations of urea, diammonium phosphate (DAP), orthophosphoric acid (OPA), and magnesium sulfate at amounts of 20, 10, 5, and 10？kg/65？m3 working volume fermenters, respectively, supported maximum ethanol production (9.8%, v/v), fermentation efficiency (FE) 88.1%, and remaining sugars (RS) 1.22%. The fermentation resulted 13.4？g dry yeast/L contained 34.6% crude protein and 8.2% ash. By selecting higher ethanol yielding yeast strain and optimizing, the fermentation parameters both yield and economics of the fermentation process can be improved. 1. Introduction Yeast selection for fuel ethanol production over the past two decades, most bioethanol related researches in developing tropical countries have focused primarily on the isolation of local Saccharomyces yeasts and their use for industrial ethanol production [1–6]. Yeasts have been isolated from many sources for industrial purposes. Such sources include cashew, apple juice [7–9], and fermenting cassava tubers [10] among others. Despite the evolving trend of using bacteria for ethanol production, yeast is still the primary choice for fermentation [11]. Yeasts are used in the fermentative production of ethanol, alcoholic beverages, baking products, protein, and vitamin supplements in human and animal diets as well as in the production of single cell proteins. However, efforts to characterize these yeasts have fallen short of expectation. In the assessment of yeasts of the genus Saccharomyces for economic and efficient ethanologenic processes, certain specific physiological properties are important and required. These include good tolerance to high concentrations of ethanol, sugars, and acids as well as high osmotic pressure [12–16]. Also good flocculation/sedimentation ability depending on process requirements as well as good invertase activity and
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