High speed, consecutive batch or continuous, low effluent process for the production of ethanol from molasses, starches, or sugars

• US 7,070,967 B2
• Filed: 08/19/2004
• Issued: 07/04/2006
• Est. Priority Date: 01/26/2001
• Status: Expired due to Fees

• Current Assignee: Bio-Process Innovation Incorporated
• Original Assignee: Bio-Process Innovation Incorporated
• Inventors: Dale, M. Clark, Moelhman, Mark
• Primary Examiner(s): Lilling, Herbert J.
• Application Number:
  US10/921,182
• Publication Number:
  US 20050019932A1
• Time in Patent Office: 684 Days
• Field of Search: 435/161, 435/163, 435/254.1, 435/255.2
• US Class Current: 435/163
• CPC Class Codes: C12P 7/06 Ethanol, i.e. non-beverage
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

A flocculent Saccharomyces cerevisae strain (BPSC-15) produces higher yields of ethanol in fermentations of fermentable sugar or fermentable starch/enzyme.

Claims

1. A method of developing an improved strain of Saccharomyces cerevisae which comprises a) a selecting a highly flocculent strain of that species, b) running a continuous single stage CSTR for a period of weeks, c) selecting, based on floc stability, a ‘

best’

pellet, d) using this pellet as a starting inoculation for running a second CSTR, e) repeating steps b), c) and d) until an obtained stable well shaped floc cell mass is capable of maintaining consistent performance over a period of time, f) improving the osmo-tolerance of the stable floc mutant obtained from step d) by growing a small pellet thereof in a high-salt medium, g) taking a single pellet from the resulting medium and growing it again in fresh medium, h) repeating steps f) and g) a number of times until a new, highly flocculent, stable, osmo-tolerant mutant strain of Saccharomyces cerevisae is obtained.

2. A method of claim 1 wherein the highly flocculent strain of step a) is S. cerevisae ATCC 60593.

3. A biologically pure culture of a Saccharomyces cerevisae strain which i) has the capability to maintain a totally floc mode characterized by yeast pellets of from 0.1 to 5 mm in diameter in a fermentation medium, ii) shows a yeast free cell (single or budding double cells) of less than 0.5 g/L with a yeast floc density as high as 100 g/L or higher, iii) has a limiting osmo-tolerance for ethanol productivity of about 5.0 os/kg, and iv) is substantially the same as an improved strain obtained by the method of claim 2.

4. A method of claim 1 wherein the mutant strain obtained from step h) i) has the capability to maintain a totally floc mode characterized by yeast pellets of from 0.1 to 5 mm in diameter in a fermentation medium, ii) shows a yeast free cell (single or budding double cells) of less than 0.5 g/L with a yeast floc density as high as 100 g/L or higher, and iii) has a limiting osmo-tolerance for ethanol productivity of about 5.0 os/kg.

5. A method of claim 4 which further comprises producing an ethanol ‘

beer’

solution in a bioreactor at a pH of between 3.0 and 8.0 and a temperature between 5° and

45°

C., from a fermentation medium comprised of a fermentable carbohydrate, optional recycle stillage, requisite nutrients and an effective amount of the obtained mutant strain of Saccharomyces cerevisae.

6. A biologically pure culture of a Saccharomyces cerevisae strain which i) has the capability to maintain a totally floc mode characterized by yeast pellets of from 0.1 to 5 mm in diameter in a fermentation medium, ii) shows a yeast free cell (single or budding double cells) of less than 0.5 g/L with a yeast floc density as high as 100 g/L or higher, iii) has a limiting osmo-tolerance for ethanol productivity of about 5.0 os/kg, and iv) is substantially the same as an improved strain obtained by the method of claim 1.

7. A biologically pure culture of a Saccharomyces cerevisae strain which i) has the capability to maintain a totally floc mode characterized by yeast pellets of from 0.1 to 5 mm in diameter in a fermentation medium, ii) shows a yeast free cell (single or budding double cells) of less than 0.5 g/L with a yeast floc density as high as 100 g/L or higher, and iii) has a limiting osmo-tolerance for ethanol productivity of about 5.0 os/kg.