Low pH lactic acid fermentation

a technology of lactic acid fermentation and low ph, which is applied in the field of low ph lactic acid fermentation, can solve the problems of fermentation not providing lactate enriched in either optical isomer, and the inhibition of end-products by organic acids (lactic acid), and achieves poor growth, high productivity free lactic acid producers, and high concentrations of free lactic acid

Inactive Publication Date: 2006-05-04
CARGILL INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006] The present invention relates to the production of lactate via fermentation. It particularly concerns fermentation with acid-tolerant bacteria to produce a fermentation broth with high levels of free lactic acid. The presence of the high level of free lactic acid can facilitate the down stream processing required to isolate lactate in its free acid form from the broth.

Problems solved by technology

Unfortunately, as with most organic acid fermentations, the end-product inhibition by the organic acid (lactic acid in this instance) can be a major obstacle to efficient fermentation.
While relatively high production levels at pH as low as 4.2 have been reported, this fermentation does not provide lactate enriched in either optical isomer.
The high cost of dialysis membranes coupled with a low lactate gradient has generally lowered the attractiveness of this approach.
The lactate production levels reportedly achieved via this method are still, however, quite low.
This both lowers the efficiency of lactate production and introduces additional potential issues with regard to the separation and purification of free lactic acid.

Method used

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Examples

Experimental program
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Effect test

example 1

Standard Fermentation Conditions

[0077] Unless otherwise indicated, the fermentation reactions described in the following examples were run using a variety of growth media according to the following standard protocol.

[0078] Cells (250 ul) were passed from a bench stock of the particular strain in 40% tomato juice / 40% LSW-MRS agar bottom phase / MRS top phase biphasic (TJ-SW-MRS biphasic) into fresh TJ-SW-MRS biphasic medium and incubated under static conditions for 18-24 hours at 47° C.

[0079] MRS Medium (pH=6.2)

10g / Lpancreatic digest of gelatin8g / Lbeef extract4g / Lyeast extract20g / Lglucose2g / LK2HPO41g / LTweenR 805g / Lsodium acetate5g / Lammonium citrate0.2g / LMgSO40.05g / LMnSO4

[0080] A 1.0 ml aliquot of the incubate in the fresh TJ-SW-MRS biphasic medium was used to inoculate 80 ml of Medium B supplemented with 10% CSL, glucose (60 g / L total concentration) and calcium carbonate (20 g / L) in a sealed serum bottle and incubated with agitation 18 hours at 47° C. in an environmental shaker.

[...

example 2

Isolation of Acid-Tolerant Homolactic Strains Without pH Control

[0083] Homolactatic bacterial strains were isolated from samples of corn steep water obtained from eight different industrial corn milling facilities. The facilities were located in Blair, Nebraska; Edyville, Iowa; Cedar Rapids, Iowa; Dayton, Ohio; Memphis, Tenn.; Istanbul, Turkey; Tillbury, England; and Bergen Op Zoon, the Netherlands.

[0084] The strains were isolated by obtaining samples of steep water from commercial corn milling facilities. The samples were plated on 10% CSL-MRS agar plates (pH 5.0) and incubated anaerobically at 47° C. Colonies were restreaked for isolation on 10% CSL-MRS agar plates. Isolates were then passed into a 40% LSW-40% tomato juice-MRS bottom phase / MRS top phase biphasic medium (pH 6.0) for maintenance purposes. The isolated strains were screened for heterolactic production by monitoring for the formation of gas (CO2) in the bottom of the tube. The homolactic isolates were then screened ...

example 3

Isolation of Acid-Tolerant Homolactic Strains Using Added Base

[0087] An additional set of homolactic strains were isolated from corn steep water samples obtained from the corn milling facilities in Edyville (Iowa), Cedar Rapids (Iowa), and Blair (Nebr.). The isolation procedure employed was the same as described in Example 2. The isolated homolactic strains were characterized based on fermentations carried out in Medium B supplemented with 10 vol. % CSL, 90 g / L glucose and 33 g / L CaCO3. The overall lactate production and / or percentage L-lactate produced were measured for this set of strains. The results are shown in Table 2 below.

TABLE 2Isolated Homolactic StrainsStrain No.g / L Lactate% L-Lac.9062819267.9599562.47449963.177810358.537510465.187510966.268311458.64611747.996212749.544412968.757713259.129513360.379513428.876313654.14113966.084714057.1894

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Abstract

A process for producing lactic acid which includes incubating acid-tolerant homolactic bacteria in nutrient medium to produce a fermentation broth with high levels of free lactic acid is provided. An isolated acid-tolerant homolactic bacteria capable of producing high levels of free lactic acid is also provided.

Description

BACKGROUND OF THE INVENTION [0001] Lactic acid and its salts have long been utilized in a wide variety of applications in the chemical, cosmetic, food and pharmaceutical industries. More recently, new bioengineering materials based on lactate, such as biodegradable lactide polymers, have kindled an increased demand for lactate and especially for the free acid form of either L- or D-lactate. The use of lactic acid in the production of various industrial polymers has been described, for example, in U.S. Pat. Nos. 5,142,023; 5,247,058; 5,258,488; 5,357,035; 5,338,822; 5,446,123; 5,539,081; 5,525,706; 5,475,080; 5,359,026; 5,484,881; 5,585,191; 5,536,807; 5,247,059; 5,274,073; 5,510,526; and 5,594,095. (The complete disclosures of these seventeen patents, which are owned by the assignee of the present application, Cargill, Inc. of Minneapolis, Minn., are incorporated herein by reference.) [0002] While chemical processes can be used to produce lactic acid, the rising cost of petrochemica...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C12P7/56C12N1/20
CPCC12N1/20C12P7/56C12R1/00C12R2001/00C12N1/00
Inventor CARLSON, TING LIUPETERS, EUGENE MAX JR.
Owner CARGILL INC
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