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Patented Oct. 8, 1946
2,408,853
UNITED STATES PATENT OFFICE
I
2,408,853
I
GUAYULE RUBBER BY FERMENTATION
Samuel R. Hoover, Philadelphia, Pa., Paul J. Al
len, Robles del Rio, Calif., and Joseph Naghski,
Philadelphia, Pa., assignors to the United
States of America as represented by the Sec
retary of Agriculture
No Drawing. Application July 21, 1944,
Serial No. 546,020
4 Claims. (Cl. 195-1)
(Granted under the act of March 3, 1883, as
amended April 30, 1928; 370 O. G. 757)
1
This application is made under the act of March
3, 1883, as amended by the act of April 30, 1928,
and the invention herein described and claimed,
if patented, may be manufactured and used by or
for the Government of the United States of
2
agar medium which containsthe resin of guayule
rubber as an emulsion, along with common bac
terial nutrients, if the latter are desired. Resin
digestion is shown by the appearance of cleared
areas around the colonies as they grow. We have
America for governmental purposes without the
demonstrated that the microbiological digestion
payment to us of any royalty thereon.
of the crude resin extracted from the rubber is
In the recovery of rubber from guayule by the
a selective process, 1. e. only certain constituents
conventional mechanical extraction method, the
present in the resin are removed by the organ
shrub is defoliated, crushed or cut, and milled 10 isms. The data presented hereinafter shows that
with pebbles in a slurry containing appropriate
marked improvement in physical properties re
solids until the rubber is agglomerated into gran
sults from incubation of the rubber with these
ules, called worms. Upon dilution of the slurry
organisms, which leads to the conclusion that
with water, the Worms ?oat to the surface and
the impurities present in the rubber that are
are skimmed off. The product recovered by these 15 removed by fermentation are those which lower
operations is boiled, usually under hydrostatic
pressure, to waterlog the particles of plant ma
terial contaminating it, and then is dried and
marketed.
the physical properties.
A variety of organisms thus selected have been
shown to improve the quality of guayule rubber
by pure culture fermentation of the worms in
Commercial guayule rubber produced by this 20 an appropriate medium under proper conditions
process contains appreciable quantities of resinous
of aeration and temperature for the particular
contaminants and plant debris. Various methods
organism. Typical data is given in Table 1,
of further purifying the product have been ‘pro
below.
posed, extraction of the resins with acetone or
Examples
other solvents having been employed commer 25
100 gms. wet weight of‘ guayule worms were
cially from time to time.
'
steam sterilized 30 minutes at l5-pound pressure,
We have found that the rubber worms pro
then fermented in 250-300 cc; of Allison’s min-_
duced by the conventional mechanical extraction
eral salts medium 1 in 2-quart jars at 30-32° C.
method can be subjected to a process of fermen
tation. By this method, only 5 to 20 percent of 30 for 10‘ days. The pH was adjusted and organic
the plant mass material is required to be handled
amendments were added to the medium as indi
and pure culture inoculum may be employed to
cated. The worms were washed and ‘air dried
at 32“ 0. Physical properties given are those at
maintain an essentially pure culture fermenta
optimum time of cure, usingthe following formula.
tion. We have also developed a method for eval
ulating the ability of organisms to grow on and 35 and conditions, referred to as “ERRL Standard”:
digest the guayule resins.
Guayule rubber worms are particles averaging
%" to 1/4" in size which on microscopic exami
Rubber
___
Captax
__
parts" 100
do___~v
1
ZnO
____
do“;
5
nation of cross sections are shown to be quite
inhomogeneous, with numerous voids and oc 40 Stearic acid _____________________ __do____ 1.5
S
>
do____ 3.5
eluded particles of bagasse. Apparently, the basic
visible unit in a worm is the contents of one cell,
many of these being pushed or stuck together to
form a worm.
Mill'I'_______________________________ __°F__ 1.15
Vuld T_____________________________ __°F__ 274
1Standard
Allison’s
medium
was
diluted
to
half
Evaluating the ability of organisms to grow on 45 strength.
and digest guayule resins comprises inoculation
All values are given at optimum time of cure
and growth of a pure or mixed culture on an
for tensile strength.
2,408,853
Table 1
Analytical results
Sample
U25W2~1°¥
Organism
I‘
”
Organic amend.
' bor ,
pH
_
Benzene Acetone Benzene Tensile Elon- Hug
extract extract
sol
strength gation shot;
7. 1
76. 28
17. 79
5. 93
2, 960
830
32
Micrococcus (unident.) _ .____
7. 0
76. 65
17. 43
5. 92
2, 650
950
31
Achromabacter lacticum l___-_ N
6. 3
6. 7
7. 4
6. 6
7. 7
7. 6
7. 0
76. 03
77. 49
78.87
78. 30
78. 04
79. 11
76. 34
17. 75
17. 21
16. 74
16. 62
17. 27
16. 25
19. 06
6. 22
5. 30
4. 39
5.08
4. 69
4. 64
6. 60
2. 280
2, 810
2, 860
2, 850
2, 860
2, 810
2, 230
970
880
840
940
910
940
940
27
32
35
33
37
31
27
. _ .. _ .
Nutrient broth ...... -.
Physical tests
_ _ . "do- _
0.2% N114 citrate ____ _.
6. 8
75. 49
18. 75
5. 79
2, 350
940
32
6. 7
75. 47
18. 80
5. 73
2, 540
950
29
1 Less satisfactory growth took place in this medium. This data is given to typify the negative results obtained with unsatisfactory growth
conditions or with organisms which do not produce the desired efiectrin any of the media tried.
tions of said resinous contaminants by fermen
On the basis of ease of culture and nutrient re-_
quirements Pseudomonas boreopolz's gave the best 0 tation, whereby the quality of the rubber is in
creased, thence removing and washing the re
results, as indicated by the following example:
sulting high quality rubber and drying it.
1000 g. wet weight of worms were incubated with
out sterilization at room temperature
2. The process of producing an improved rub
(about ‘
ber from guayule rubber worms, comprising sus
86-88° F.) in 5 liters of half strength Allison's
solution to which was added 0.1% ammonium 25 pending the worms in water, inoculating the mix
ture with Pseudomonas boreopolis organisms,
citrate and 0.15% KzIH’Or. 100 cc. of a 2 day
conditioning the medium for growth of the or
nutrient resin broth culture of Ps. boreopolis was
ganisms, allowing the organisms to grow until
added at 0 days and 100 cc. more of a 1 day cul
the resin content of the worms is substantially de
ture was added the third day. Fermentation was
carried out in an open crock and aeration was 30 creased, whereby the physical properties of the
rubber will be improved, then removing and
maintained by compressed air bubbling vigorous
washing the improved rubber and drying it.
ly from a tube running to the bottom of the crock.
Table 2
Analytical composition
ERRL standard formula
std'?l?gyg’agle'ggggnodi‘
Day
Benzene
Acetone
extract
insoluble
Tensile
Per cent
Per cent
Per cent
P. s. i.
75. 45
77. 77
78. 75
80. 31
80. 99
18. 20
16. 28
14. 61
13. 87
12. 45
6.
5. 95
6. 64
5. 82
6. 66
extract
C ontrol .... __
5 ___________ __
8 ___________ __
12 __________ __
20 __________ __
Benzene
-
2, 400
2, 860
3, 020
3, 060
3, 280
Modulus
at 600%
-
Elong'
Tens?e
Per cent
P. s. 1‘.
270
440
500
430
660
940
890
880
900
860
3, 120
3, 380
3, 450
3, 710
3, 790
Modulus
at 600%
Elong'
Per cent
030
1, 070
l, 120
1, 190
1, 080
840
800
800
790
800
The accelerating e?ect of p,p'-diaminodiphenyl
methane upon the physical properties of the rub
ber was essentially additive upon the improve
3. The process of producing an improved rub
ber from guayule rubber worms, comprising sus
pending the worms in water, inoculating the mix
ment due to the fermentation.
A boiling treatment or a heating under hydro
static pressure (paila treatment) is convention
ture with Aspergillus fumigatus organisms, con
ditioning the medium for growth of the organ
isms, allowing the organisms to grow until the
ally used in the guayule rubber industry to water
log the cellulosic debris present in the worms,
thus causing it to sink and be separated from the
resin content of the worms is substantially de
creased, whereby the physical properties of the
rubber will be improved, then removing and
Washing the improved rubber and drying it.
?oating rubber. The worms coming from this
step of the process are at least partially sterilized
and in excellent condition for a subsequent fer
mentation step. The worms treated by our proc
4. The process of producing an improved rub
beer from guayule rubber worms, comprising sus
pending the worms in water, inoculating the mix
ess can be washed in water by a variety of means, 60 ture with Trz'choderma sp. organisms, condition
ing the medium for growth of the organisms, al
lowing the organisms to grow until the resin con
tent of the worms is substantially .decreasedi,
such as on a screen or by successive changes of
water, and then dried in the conventional man
ner.
Having thus described our invention, we claim:
1. The process of extracting high quality rub
ber from guayule rubber plants comprising me
- whereby the physical properties of the rubber
65 will be improved, then removing and washing the
chanically separating rubber worms from the
plant bulk, which worms will normally contain
resinous contaminants, suspending the worms in
water, selectively decomposing substantial por 70
improved rubber and drying it.
SAMUEL R. HOOVER.
PAUL J. ALLEN.
JOSEPH NAGHSKI.
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