 Production of esters of lactic acid, esters of acrylic acid, lactic acid, and acrylic acid |
| OF THE PREFERRED EMBODIMENTS The following disclosure of the invention is submitted in furtherance ... |
|
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| Method for producing the ACCI restriction endonuclease and methylase |
| In accordance with the present invention there is provided a clone containing the genes for the AccI... |
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| Process for preparing optically active 3,3,3-trifluoromethyl-2-alkylpropionic acid derivatives |
| What is claimed is: 1. A process for preparing optically active 3,3,3-trifluoro-2-alkylpropionic ... |
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| Process for the fermentative production of L-amino acids using coryneform bacteria |
| OF THE INVENTION The present invention is illustrated in greater detail by the following practical ... |
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| Apparatus for cooling newly formed glass containers |
| A method of and apparatus for reducing the noise resulting from cooling air at the dead plate of a ... |
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| Apparatus for cultivating algae |
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| Cyanobacterium-produced bioemulsifier composition and solution thereof |
| It is an object of the invention to provide a process for the production of a novel emulsifying ... |
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Membrane-based process for the recovery of lactic acid by fermentation of carbohydrate substrates containing sugars
| Details |
Inventors: Russo, Jr., Lawrence J.; Kim, Hyung S.;
Assignee:
Primary Examiner: Spear; Frank
Assistant Examiner:
Attorney, Agent or Firm: Lobo; Alfred D.
A substantially continuous membrane separation process has been discovered in which the known benefits of a cell-recycle fermentor are unexpectedly enhanced because pH is controlled from 4.0 to 5.5 with a nitrogen-containing base. The ammonium lactate formed is not precipitated, allowing continuous removal of lactic acid so as to maintain a concentration of lactic acid about 12% by wt in the broth. When combined with recycle of UF retentate, operating this cell-recycle fermentor allows the build-up of a cell population in the range from above 5.times.10.sup.9 CFU/ml to 5.times.10.sup.10 CFU/ml, which population is much denser than one which can be produced with the specified pH control in a batch fermentor, after self-termination of the fermentation. This super-dense population of cells, In turn, not only accelerates production of lactic acid but also minimizes contamination by foreign cells. UF retentate is recycled to produce a specified high fluid velocity when the effluent stream is flowed over UF membranes used in the UF modules. The high fluid velocity at relatively low pressure produces a scrubbing action over the membrane surfaces which are therefore not fouled over long periods of operation. In a batch fermentation with pH control, when the fermentation is self-terminated the total lactic acid present is about 10% by wt (measured by HPLC), though free lactic acid is always <4%, and the live cell population is lower than 5.times.10.sup.9 CFU/ml because many cells die as pH drops. |
|
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Lactic acid, a large portion of which is ionized at a temperature in the range from about 30.
degree.
C.
to 45.
degree.
C.
, is recovered from the broth preferably at from 35.
degree.
C.
to 42.
degree.
C.
, by a combination of filtration steps.
The purity of lactic acid recovered depends upon the nutrients used for growth of the microorganisms used in the fermentation.
The temperature of the fermentation determines that a large proportion of the lactic acid is ionized, and the ionic species of lactic acid are found to make separation of lactic acid from the broth, unexpectedly effective, so long as the separation is effected in a series of membrane separation means which at the very least, requires a combination of three filtration zones operating in series, including a first UF zone with a UF membrane having a pore size no greater than about three-fourths (0.
75 times) the smallest dimension of a single colony forming unit or CFU, or living microorganism (hence referred to as "cell-matched"); a second NF zone with a semipermeable NF membrane; and, a third RO zone, with a semipermeable RO membrane.
The following recipe is for a fermentable broth in which thin stillage is used as a supplemental nutrient.
The ingredients of the mash are as follows:
______________________________________
Ingredient Range, % by wt (wet basis)
______________________________________
Mashed corn 5 to 25
Yeast Extract
0.
05 to 0.
8
Buffers 0.
2 to 0.
8
Thin stillage
2 to 8
______________________________________
An analogous fermentation product may be used, which product is obtained from the submerged culture fermentation of molasses, potatoes or, especially, starch provided by other grains, by bioconversion using Lactobacillus delbrueckii, L.
bulgarcius or L.
leichnanii, or any other microorganism which generates lactic acid.
The fermentation product will have a composition exemplified by:
______________________________________
wt
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Molecular Biology 
