By applying the Arkenol process using highly concentrated sulfuric acid, various biomass feedstocks, including cedar tree, rice straw, newspaper, and bagasse, were successfully processed and converted into glucose and xylose for fermentation usage in a flash fermentation reactor in which the performance of National Renewable Energy Laboratory's patented rec-Zymomonas mobilis 31821 (pZB5) after immobilization was investigated. The immobilization medium is a photocrosslinked resin made from polyethylene glycols or polypropylene glycols. Recombinant or rec-Z. mobilis used in the study has been shown to efficiently ferment glucose and xylose at a relatively high concentration (12-15%), that is a typical hydrolysate produced from cellulosic feedstocks. The application of immobilized rec-Z. mobilis and flash fermentation technology, together with concentrated acid technology producing a high concentration sugar solution, promises to speed the development of the cellulose-to-ethanol industry.