Abstract:
Methods of degrading napalm and/or trinitrotoluene involve contacting the waste with specific intra-amoebic isolates of ATCC 40908 and/or dispersants derived therefrom. Useful isolates include is deposited as ATCC 77529, NAP-1 deposited as ATCC 77526 and 13 deposited as ATCC 77527.

Description:
The United States Government has rights in this invention pursuant to contract No. DE-AC05-84OR21400 between the United States Department of Energy and Martin Marietta Energy Systems, Inc. 
    
    
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 08/011,841, filed on Feb. 1, 1993, now U.S. Pat. No. 5,314,821, issued on May 24, 1994, entitled Amoeba/Bacteria Consortia and Uses for Degrading Wastes and Contaminants, the entire disclosure of which is incorporated herein by reference application Ser. No. 08/011,841 is a continuation of application Ser. No. 07/693,998, filed on Apr. 26, 1991, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to methods of biological degradation of napalm and trinitrotoluene (TNT), and more particularly to such methods which utilize intra-amoebic isolates. Napalm, as used herein, is defined as Napalm B, a mxiture of gasoline, benzene, and polystyrene. The original, obsolete napalm formula, containing napthenic and palmitic acids, has not been tested. 
     BACKGROUND OF THE INVENTION 
     The end of the &#34;cold war&#34; has brought about the need for the reduction or elimination of many weapons stockpiles. Among those are explosives and incendiaries which, for the sake of protecting the environment, can no longer be burned. Therefore there is a need for alternative methods for eliminating explosives and incendiaries, in particular, waste napalm and TNT. 
     OBJECTS OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a new and improved method of biological degradation of napalm. 
     It is another object of the present invention to provide a new and improved method of biological degradation of TNT. 
     Further and other objects of the present invention will become apparent from the description contained herein. 
     SUMMARY OF THE INVENTION In accordance with one aspect of the invention, the foregoing and other objects are achieved by a method of degrading napalm which involves the steps of: 
     a. providing a culture of a bacterium which comprises an intra-amoebic isolate essentially identical to American Type Culture Collection Deposit Number 77529, a mutant thereof possessing all the identifying characteristics thereof, or mixtures thereof; 
     b. deriving an aqueous dispersant solution from the culture; 
     c. contacting napalm B with a sufficient amount of the dispersant solution to emulsify the napalm B; and, 
     d. contacting the emulsified napalm B with a sufficient amount of at least one of intraamoebic isolates essentially identical to American Type Culture Collection Deposit Numbers 77526 and 77527, a mutant thereof possessing all the identifying characteristics thereof, or mixtures thereof, to degrade the emulsified napalm B. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Amoeba/bacteria consortium 46, ATCC Deposit Reference No. 40908, was found to contain certain useful bacteria, designated as intra-amoebic isolates 13, NAP-1, 1S and CR-1. Isolate 1S produces a biodispersant which separates the components of napalm, and also elutes TNT bound to soil. Isolates NAP-1 and 13, in combination with the biodispersant produced from isolate 1S, degrade and disperse the polystyrene component of napalm. Isolate CR-1 degrades TNT in a manner which renders it undetectable by standard analysis methods. 
     The method of deriving a dispersant and using it to separate components of napalm is described in general terms as follows: Isolate 1S is usually grown on culture plates containing a solid medium. A typical solid medium suitable for this purpose comprises 15g/L Bacto Tryptone (Pancreatic Digest of Casein), 5g/L Bacto Soytone (Papaic Digest of Soybean Meal), 5g/L Sodium Chloride and 15g/L Bacto Agar. Small amounts of freshly grown bacteria (typically 1-3 day old cultures) are spread on the surface of the solid medium and incubated at a temperature of about 15° C. to about 40° C., preferably about 30° C., for several days (usually about 3-5 days) in an aerobic environment. When growth is sufficiently heavy, the bacteria are harvested, washed by centrifugation (usually about three times) with normal saline (about 8.5g/L NaCl), diluted (to about 10 ml for each culture plate used) with normal saline, and autoclaved (typically for about 15 minutes at 121° C. at 15 psi). The autoclaved solution is allowed to cool, and is preferably filtered through a 0.2μm nucleopore filter to remove extraneous membranes and other bacterial debris. The biodispersant solution thus derived is preferably stored in a sterile container. The biodispersant solution is preferably diluted 1:10 with sterile distilled water for use in separation of napalm components. 
     Napalm typically composed of polystyrene, leaded gasoline, and benzene, is degraded as follows: Napalm, preferably in its liquid form, is added to the diluted biodispersant solution. The mixture should generally contain about 5% to about 25%, preferably about 10%, napalm. Upon thorough mixing, an emulsifying effect is observed in the mixture, indicating suspension of the polystyrene component of the napalm. 
     To further degrade the mixture, a supernatant bacterial preparation containing about 10 3  /ml to about 10 8  /ml, usually about 10 5  /ml, isolate 13 and/or isolate NAP-1, preferably both, is added to the emulsified mixture in a ratio of about 3:1 to about 1:3, preferably about 1:1. The mixture is then incubated at a temperature of about 15° C. to about 40° C., preferably about 30° C., until the polystyrene component of the napalm has dissolved, usually at least 24 hours. Marked increases in breakdown products of polystyrene, indicative of its degradation, will be evident, as seen in Table 1. 
    
    
     EXAMPLE 
     A dispersant was derived from Isolate 1S as described hereinabove, and was mixed with napalm as described hereinabove to produce an emulsified mixture containing a suspension of the polystyrene component of the napalm. Results are shown in Table 1. 
     EXAMPLE II 
     Isolate 13 and isolate NAP-1 were grown separately on Trypticase Soy Agar at 30° C. for 3 days and harvested dry. The bacteria were prepared and used as described hereinabove to degrade the mixture produced in Example I. Results are shown in Table 1. 
     
                       TABLE 1______________________________________Effect of Isolates 13 and Nap-1 on Volatile AromaticComponents of Napalm    Water   Bio-      Biodispersant +    Control dispersant                      Isolates 13, NAP-1______________________________________Benzene in:Polystyrene.sup.a      37,000,000                28,000,000                          38,000,000Supernate.sup.b      140,000   320,000   110,000Ethyl Benzene in:Polystyrene      80,000    80,000    150,000Supernate  420       620       150,000Toluene in:Polystyrene      81,000    91,000    130,000Supernate  1,800     2,400     210,000Total xylene in:Polystyrene      180,000   150,000   280,000Supernate  1,200     820       260,000______________________________________ .sup.a μg/kg (semi solid portion of mixture) .sup.b μg/L (liquid portion of mixture) 
    
     A general, simple method of treating soil contaminated with TNT is described as follows. Soil contaminated with TNT is loaded into a vessel, usually a column, for contacting the soil with a biodispersant. An aqueous solution containing biodispersant derived from isolate 1 S (as described hereinabove) is added and allowed to percolate down through the soil and elute the TNT. The solution may be forced through the soil, the soil may be pretreated, and/or other process steps known to the skilled artisan may be taken to increase the efficiency of the process. The process may be carried out at about room temperature, but process temperature is not a particularly critical factor. 
     EXAMPLE III 
     10 grams of contaminated soil were loaded into two columns, 7 in. in height with a diameter of 2.0 inches, each column having a Whatman #1 filter pad 
     in the bottom thereof to retain the soil. One column was eluted with 100 ml 
     distilled, deionized water, and the other column was eluted with 100 ml of the above described dispersant solution. The flow rate through the soil was slow, requiring 12 hours for all the liquid to pass through the columns. The eluate and soil for both the control and test columns were collected and analyzed for TNT and metabolites after acetonitrile extraction. No metabolites were detected. The results are shown in Table 2, indicating a significant reduction in detectable TNT in the soil eluted with the biodispersant solution. 
     
                       TABLE 2______________________________________Desorption of TNT from Soil Using Biodispersants fromIsolate 1S    VA Site (soil)             NJ Site (soil)                        NJ Site (eluate)______________________________________Water Control      5,900 μg/g                 370 μg/g                            15,750 μg/L10% Biodispersant      1,900 μg/g                  5.3 μg/g                             1,100 μg/L______________________________________ 
    
     A method of degrading TNT using isolate CR-1 is as follows. A solution is prepared containing a mineral salts solution, usually NATE, and about 20 mg/L to about 200 rag/L, usually about 50 mg/L, TNT. Isolate CR-1 is grown on a suitable medium, usually Trypticase Soy Agar, for generally 1-2 days at about 15° C. to about 40° C., usually about 30° C., and harvested dry. Isolate CR-1 is added to the TNT solution at a concentration of about 10 3  /ml to about 10 9  /ml, usually about 106/ml, followed by incubation at about 15° C. to about 40° C., usually about 30° C., to degrade the TNT. 
     A typical NATE solution is generally prepared using the following materials: 
     Solution A (10X stock) 
     10 g/L MgSO 4 . 7H 2  O 
     2 g/L CaCl 2   
     10 g/L KNO 3   
     1 g/L NH 4  Cl 
     Solution B (100X stock) 
     5 mg/L CuSO 4 . 5H 2  O 
     1 mg/L H3BO 3   
     1 mg/L MnSO 4  or 0.76 mg/L MNSO 4 . 1 H 2  O 
     7 mg/L ZnSO 4   
     1 mg/L MoO 3   
     1 mg/L CoCl 2 . 6H 2  O 
     Phosphate Buffer 
     8.5 g KH 2  PO 4  and 6.5 g K 2  HPO 4  in 300 ml 
     Iron Chloride 
     0.027 g/100 ml FeCl 3   
     To prepare a typical NATE media, 100 ml of solution B is added to 1 liter of solution A, resulting in a 10X NATE solution which can be autoclaved (sterilized). After cooling, the sterilized 10X NATE solution is diluted 1:10 with sterile water to obtain a 1X NATE solution. To 1 liter of the 1X NATE solution is added 20 ml filter sterilized phosphate buffer and add 10 ml of filter sterilized FeCl 3  to obtain the finished NATE media. 
     EXAMPLE IV 
     TNT was dissolved in water and diluted 1:1 with NATE media in a test bottle, resulting in a solution containing about 50 mg/L TNT. Isolate CR-1 was grown on Trypticase Soy Agar for 1-2 days at 30° C. and then harvested dry. Isolate CR-1 was then added to the TNT/NATE solution at a concentration of 10 6  /ml, followed by incubation at 30° C. until the solution had attained a stable yellow-orange color. A control for this experiment was similar to the test, with the organisms killed by autoclaving prior to addition to the test bottle. Each bottle was analyzed by high pressure liquid chromatography (HPLC) and showed a marked decrease in TNT levels by the live bacteria. Small quantities of 4-amino-2,6-dinitrotoluene (4-ADNT), one of the metabolites associated with the degradation of TNT, were detected as indicated in Table 3. 
     
                       TABLE 3______________________________________CONCENTRATION OF TNT AND ITS METABOLITESAFTER INCUBATION WITH BACTERIA ISOLATECR-1Isolate      TNT, mg/L  4-ADNT, mg/L______________________________________CR-1         36         0(5 minutes)CR-1         10         0.3(24 hours)Control      48         0(24 hours)______________________________________ 
    
     EXAMPLE VI 
     Additional experiments were then undertaken using a similar protocol as previously mentioned except that the saturated TNT solution now contained  14  C-labeled TNT. Most of the  4  C-TNT was associated with the cell pellet. Further analysis of the cell pellet showed no detectable TNT present. TNT metabolites were detected in small amounts in the test bottles. Results are shown in Tables 4 and 6. 
     
                       TABLE 4______________________________________% .sup.14 C-TNT per fractionEXPERIMENT   Cell Pellet  CO.sub.2                            Soluble______________________________________1            70           1      292            66           2      32Control       6           4      90______________________________________ 
    
     
                       TABLE 5______________________________________% TNT and Metabolites in Cell PelletEXPERIMENT   TNT       2-ADNT   4-ADNT______________________________________1            0.0       0.009    0.042            0.0       0.005    0.05Control      0.0       0.000    0.00______________________________________ 
    
     Deposit of Microorganisms 
     The applicants, in accordance with the provisions of the Budapest treaty on the international recognition of the deposit of microorganisms for the purposes of patent procedure under the Budapest Treaty, did deposit samples of Isolate NAP-1, Isolate 13, Isolate CR-1, and Isolate 1S with the American Type Culture Collection (ATCC), 12301 Parklawn Drive, Rockville, Md. 20852, U.S.A. on Aug. 20, 1993 and assigned ATCC deposit reference Numbers 77526, 77527, 77528, and 77529, respectively. Each culture is hereby irrevocably and without restriction or condition released to the public upon the issuance of letters patent herefor. 
     While there has been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the inventions defined by the appended claims.