Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing compound containing saccharide radical
Reexamination Certificate
1999-12-21
2001-06-26
Lilling, Herbert J. (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing compound containing saccharide radical
C435S072000, C435S104000, C435S875000
Reexamination Certificate
active
06251641
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to compositions and methods for the recovery of bacterial exopolymers for food, personal care, pharmaceutical, petroleum and other industries requiring high quality viscosifiers, bioemulsifiers and biodegradable polymers.
BACKGROUND OF THE INVENTION
There is an ever increasing demand for inexpensive and environmentally acceptable viscosifiers, bioemulsifiers and biodegradable polymers. The biotechnology industry has responded with increasing the availability of a variety of bacterial cell products that may find their way into commercial use. Although many of the bacterial products offer a wide range of attractive improvements over synthetically produced materials, they remain relatively expensive to produce. The expense is generally associated with costs of recovery and purification of the desired product.
Higher yields of biopolymers are the result of a better understanding of biosynthesis and optimization of fermentation conditions. This satisfies one of the important steps in recovering adequate amounts of the polymer for potential industrial applications. Nonetheless, recovery of these polymers remains a difficult and costly step. Recovery of a biopolymer, regardless of the conditions used to produce it, typically involves a precipitation step; the precipitated biopolymer is recovered by centrifugation.
There are two major inefficiencies associated with a typical recovery protocol. The first problem arises if significant numbers of the producing population are killed by the precipitation protocol. The viable biomass must then be reinoculated and allowed to equilibrate to the conditions optimal for the recovery of the biopolymer. These steps require the addition of nutrients and energy that increase the cost of producing the biopolymer. Another major inefficiency is incomplete recovery of the biopolymer of interest. Different bacterial exopolymers are attached to (or associated with) the producing cells with varying degrees of tenacity. Those bacteria that have relatively securely attached exopolymers are less likely to shed them into the medium, thus reducing the amount of exopolymer available for recovery in the precipitation step.
The compositions of the present invention have demonstrated their ability to significantly increase the recovery of exopolymer from a microbial culture. The materials do not apparently affect the amount of exopolymer produced by the bacterial cells, but serve only to increase the efficiency of exopolymer recovery.
SUMMARY OF THE INVENTION
The present invention provides for compositions and methods for enhancing recovery of exopolysaccharide polymers from bacterial cells. The compositions and methods of the present invention neither interfere with the viability of the producing strains of bacteria, nor enhance the production of the exopolymer; the materials increase exopolymer recovery. The method of the present invention comprises adding to the cultivation medium (i.e., a nutrient solution for microorganisms to grow within) an effective amount of an alkyl-sulfosuccinate surfactant in order to induce the desired response. The method also comprises the inclusion of a nonionic block copolymer in conjunction with the alkylsulfosuccinate that further enhances the recovery of the exopolymer while reducing the required amount of sulfosuccinate.
REFERENCES:
patent: 2296249 (1996-06-01), None
Evans et al., Journal of Antimicrobial Chemotherapy (1990) 25, 585-591.
Cerning et al., J. Diary Sci., (1992) 75: 692-699.
DuBois et al., Analytical Chemistry, vol. 28, No. 3, Mar. 1956, 350-356.
Buckmire et al., Microbios, (1984), 41, 49-63, 1984.
Lawford et al., “Bioreactor Design Considerations in the Production of High-Quality Microbial Exopolysaccharide,”Applied Biochemistry and Biotechnology, vol. 28/29, 1991, p. 667-83.
BetzDearborn Inc.
Boyd Steven D.
Lilling Herbert J.
Paikoff Richard A.
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