Unisearch Limited

David E Tribe

Peter L Rogers

An improved method for the production of ethanol from a fermentable carbohydrates such as glucose, fructose or sucrose using the bacterium Zymomonas mobilis which method involves continuously culturing the bacterium in a culture medium containing the fermentable carbohydrate, continuously drawing off a portion of the culture medium and replacing that portion with fresh culture medium, separating from the removed portion of the culture medium cells of Zymomonas mobilis contained therein and returning those cells to the culture medium and recovering the ethanol contained in the portion of the culture medium from which the cells have been removed. It has been found that this method results in greatly improved ethanol production without the disadvantages which have been found when yeasts are continuously cultured.

Ethanol production in a continuous process with cell recycle

A process for the production of ethanol from a carbohydrate substrate such as glucose comprising culturing a flocculant strain of Zymomonas mobilis such as ATCC 31822, in a semi-batch manner periodically allowing the flocculent cells to settle, removing the ethanol containing supernatant and introducing fresh fermentation medium into the fermentor.

Semibatch ethanol production

A method of producing ethanol (alcohol) comprising culturing in a suitable means a strain of Zymomonas mobilis which has a specific ethanol productivity at 30.degree. C., pH5 and in a medium containing 300 g/l glucose of at least 4.0 g/g/h; a specific rate of glucose uptake at 30.degree. C., pH5 and a medium containing 200 g/l glucose of at least 8.0 g/g/h; and an ethanol tolerance level at 30.degree. C., pH5 and in a medium containing 300 g/l of glucose of at least 120 g/l ethanol in a batch culture or of at least 60 g/l ethanol in a continuous culture at 30.degree. C., pH5 and in a medium containing 150 g/l glucose.

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Maroubra, Australia

David E Tribe