Chemistry: molecular biology and microbiology – Process of utilizing an enzyme or micro-organism to destroy... – Destruction of hazardous or toxic waste
Reexamination Certificate
1999-04-26
2001-10-09
Saucier, Sandra E. (Department: 1651)
Chemistry: molecular biology and microbiology
Process of utilizing an enzyme or micro-organism to destroy...
Destruction of hazardous or toxic waste
C435S253300, C435S875000
Reexamination Certificate
active
06300121
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to means of rendering environmental lead innocuous by assimilation into microorganisms. Using the methods of the invention, the lead is sequestered in an insoluble form. In addition, the organism is able to sequester other heavy metals such as cadmium and arsenic.
BACKGROUND OF THE INVENTION
Lead in the environment presents a significant health risk, especially to children. Lead-based paint from older buildings has been one of the primary sources of lead-caused morbidity. The ability of microorganisms to bioaccumulate or to remove heavy metals from aqueous systems has been noted. Applications have included removal of metals from sewage or industrial effluent and mining of precious heavy metals, and for recovering polluting metals from geothermal ponds. However, lead removal from soil can be more difficult due to the chemistry of binding mechanisms in the soil.
Vesper, et al, (“Microbial Removal of Lead from Solid Media and Soil”.
Water, Air
, &
Soil Pollution.
86:207-219 (1996) reported use of a strain of
Pseudomonas aeruginosa
(the organism used in the instant application) to remove lead from solidified media and soil. However, they did not report use of the organism in the presence of phosphate to provide an insoluble form of lead, but only reported that the organism could sequester lead. There is no suggestion therein that the organisms could sequester other heavy metals.
Ryan, et al, in U.S. Pat. No. 5,512,702, teaches that addition of calcium phosphate to lead-containing soil resulted in formation of insoluble lead phosphate. However, no use of any microorganisms is reported or suggested therein. Furthermore, the calcium phosphate required therein, while appropriate for use in soil, would not necessarily be appropriate for use in other ecosystems or in solutions containing lead or other heavy metals. Significant theoretical and experimental evidence supports the hypothesis that lead phosphates are the most insoluble and stable forms of Pb in soils. Among all the Pb-P minerals, chloropyromorphite has one of the lowest solubilities; thus it is one of the most stable under favorable environmental conditions (Nriagu, J. O., “Lead Orthophosphates-II. Stability of Chloropyromorphite at 25° C.”
Geochim. Cosmochim. Acta.
37:367-377 (1973)). Formation of chloropyro-morphite [Pb
10
(PO
4
)
6
Cl
2
] in soils contaminated through mining activities was reported by Cotter-Howells and Thornton (“Sources and Pathways of Environmental Lead to Children in a Derbyshire Mining Village.”
Environ, Geochem, Health.
12:127-135 (1991)). Further, they illustrated that the blood Pb levels of children exposed to these contaminated soils was not elevated thus implying that this form of soil Pb is unavailable.
SUMMARY OF THE INVENTION
The instant invention provides means of reducing bioavailability of lead in the environment by addition of microorganisms which sequester lead from the environment in the presence of phosphate. The microorganisms are highly mobile and are, therefore, capable of scavenging a material for lead, which they then sequester. The method basically consists of reducing bioavailability of lead in the environment by addition of
Pseudomonas aeruginosa
strain CHL004 to said environment in the presence of phosphate which contains at least stoichiometric equivalent amounts of phosphate to lead.
It has now been found that the organism described herein is capable of sequestering other heavy metals. Examples of such heavy metals include cadmium and arsenic. These metals may also be sequestered in the bacteria in the form of salts (not necessarily phosphate salts).
The organism may be grown on a solid matrix such as charcoal or a synthetic polymer. The matrix with the organism is then added to the substrate from which the heavy metal is to be extracted.
REFERENCES:
patent: 5055402 (1991-10-01), Greene et al.
patent: 5443729 (1995-08-01), Sly et al.
patent: 5512702 (1996-04-01), Ryan et al.
Vesper et al. Water, Air and Soil Pollution. 1996. 86:207-219.*
Aickin et al. Micribios Letters. 1978. 9 (34), 55-66.*
ATCC Bacteria and Bacteriophages. Catalogue. 19 th edition. 1996, p. 277.
Davis-Hoover Wendy J.
Vesper Stephen J.
Afremova Vera
Ehrlich Alan M.
Hendricks Glenna
Saucier Sandra E.
The United States of America as represented by the Administrator
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