Non-sterile fermentation of bioethanol

• US 8,703,453 B2
• Filed: 01/24/2012
• Issued: 04/22/2014
• Est. Priority Date: 12/21/2007
• Status: Expired due to Fees

• Current Assignee: Inbicon A/S
• Original Assignee: Inbicon A/S
• Inventors: Larsen, Jan
• Primary Examiner(s): Weber, Jon P
• Assistant Examiner(s): Knight, Teresa E
• Application Number:
  US13/356,664
• Publication Number:
  US 20120122174A1
• Time in Patent Office: 819 Days
• Field of Search: None
• US Class Current: 435/161
• CPC Class Codes: A01N 43/08 with oxygen as the ring hetero atom
• CPC Class Codes: A01N 61/00 Biocides, pest repellants or attractants, or plant growth regulators containing substances of unknown or undetermined composition, e.g. substances characterised only by the mode of action
• CPC Class Codes: A01N 65/00 Biocides, pest repellants or attractants, or plant growth regulators containing material from algae, lichens, bryophyta, multi-cellular fungi or plants, or extracts thereof containing compounds of determined constitution A01N27/00 - A01N59/00
• CPC Class Codes: A01N 65/44 Poaceae or Gramineae [Grass family], e.g. bamboo, lemon grass or citronella grass
• CPC Class Codes: C12N 1/22 Processes using, or culture media containing, cellulose or hydrolysates thereof
• CPC Class Codes: C12P 2201/00 Pretreatment of cellulosic or lignocellulosic material for subsequent enzymatic treatment or hydrolysis
• CPC Class Codes: C12P 7/06 Ethanol, i.e. non-beverage
• CPC Class Codes: C12P 7/10 substrate containing cellulosic material
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

A range of concentrations exists in which fermentation inhibitors derived from pretreatment of lignocellulosic feed stocks inhibit growth of lactic acid bacteria without affecting fermentive yeast. By optimizing levels of fermentation inhibitors to fall within this range, yeast fermentations of lignocellulosic biomass can be conducted under non-sterile conditions with ethanol yields comparable to those achieved under sterile conditions. Optimised inhibitor levels can be achieved by controlling the water/biomass ratio of a lignocellulosic biomass during and after pretreatment, for example by washing the fiber fraction of a previously pretreated lignocellulosic biomass with a pre-defined amount of fresh water or recycled process solutions. Crude extracts of liquid fraction or process solutions from pretreatment of lignocellulosic biomass can also provide an effective anti-baterial treatment for first generation starch fermentations.

Claims

1. A method of yeast fermentation of starch biomass comprising the steps of:

preparing a non-sterile yeast fermentation mixture comprising primarily starch biomass and optimized levels of fermentation inhibitors that inhibit contaminating bacterial growth and/or lactate production while having substantially no effect on ethanol fermentive yeast, and

fermenting said fermentation mixture,

wherein optimized levels of fermentation inhibitors are achieved by addition of isolated and/or concentrated extracts from liquid fraction or wash waters of pretreated lignocellulosic biomass.

2. The method of claim 1 wherein the extracts comprise a portion of liquid fraction remaining after useful C5 sugars have been removed.

3. The method of claim 1 wherein the extracts comprise a portion of liquid fraction remaining after useful C5 sugars have been removed and extracts have been concentrated to a concentrated liquid.

4. The method of claim 1 wherein the extracts comprise a portion of liquid fraction remaining after hazardous or unwanted materials have been removed.

5. The method of claim 1 wherein the extracts comprise a portion of liquid fraction remaining after hazardous or unwanted materials have been removed and extracts have been concentrated to a concentrated liquid.

6. The method of claim 1 wherein the extracts are derived from liquid fraction or wash waters from steam pretreated corn stover, wheat straw or bagasse.

7. The method of claim 1 wherein said lignocellulosic biomass is pretreated to a severity index of at least 3.0.