NOVELTY - Method for producing ethanol from cellulose, comprises: (a) inoculating an aqueous mixture comprising the cellulose with a first consortium, where the first consortium comprises a bacteria species which uses a carbon source as its electron donor and an electron acceptor which is iron ion (Fe(3+)), and the bacteria species expresses enzymes which hydrolyze the cellulose to produce fermentable sugars; and (b) inoculating the aqueous mixture with a second consortium of microorganisms comprising at least one species which is capable of fermenting the fermentable sugars produced from step (a).    USE - The method is useful to produce ethanol, which is useful in beverages and food, as an industrial chemical, as a gasoline additive, and as a fuel or gasoline replacement.    ADVANTAGE - The method is efficient and economical. The method improves the yield of ethanol. The method does not require: acid hydrolysis, hence there is no problem with disposal of waste acid; and require the addition of any commercially generated enzymes. The saccharification and fermentation can be conducted in a single fermentation reactor. The method has the ability to switch between producing ethanol or methane by the simple process of adding a small amount of oxygen for ethanol production and by excluding oxygen for methane production. The method employs by-products from harvesting agricultural products which are very abundant.    DETAILED DESCRIPTION - Method for producing ethanol from cellulose, comprises: (a) inoculating an aqueous mixture comprising the cellulose with a first consortium of ethanologenic microorganisms comprising bacteria and/or fungi, where the first consortium comprises at least one bacteria species which uses a carbon source as its electron donor and an electron acceptor which is iron ion (Fe(3+)), and the bacteria species expresses enzymes which hydrolyze the cellulose to produce fermentable sugars; and (b) inoculating the aqueous mixture with a second consortium of microorganisms comprising at least one species which is capable of fermenting the fermentable sugars produced from step (a), where the fermentable sugars are produced without using acid hydrolysis and additional enzymes. An INDEPENDENT CLAIM is included for a method for producing fermentable sugars, comprising providing a cellulose and adding to the source of cellulose a first consortium of ethanologenic microorganisms, where the consortium comprises the bacteria species which uses carbon as an electron donor and Fe(3+) as an electron acceptor, the microorganisms produce enzymes sufficient for enzymatic hydrolysis of the cellulose to fermentable sugars.