Note: Descriptions are shown in the official language in which they were submitted.
~ - 1 ; 1 3~9 1 59
The present invention relates to high molecular weight
homopolysaccharides, their extra-cellular preparation
and their use, and corresponding fungal strains.
,
Water-soluble biopolymers are used in indus-try
for various applications. U.S. Patent 3,301,848 issued
on January 31, 1967 to the Allsbury Company describes
water-soluble, nonionic polysaccharides of defined structure
~ as glucans. These are produced microbially as metabolites
J''~: by growing the microorganism sclerotium glucanicum n.sp.,
NRRL 3006. However, they have a relatively low molecular
:, .
weight. The same applies to the polysaccharides described
in British Patent 2,178,~37 published on February 11,
1987 in the name of Sociéte Nationale ELF Aquitaine.
; W.L. Griffith and ~.L. Compere, in Dev. Ind.
Microbiol. 19 (1977), 609-617, describe the microbial
production of highly viscous glucans by cultivation of
the micro-organism Sclerotium rolfsii, ATCC 15206, in
a nutrient medium containing inorganic salts, glucose
, and a small amount of yeast extract, with a growth period
`~ 20 of 2.5 days. The glucans produced exhibit a decrease
in solubility in water at pH 1.5-~.
The present invention relates to a process for
~ the extracellular preparation of homopolysaccharides (PS)
'l having a high specific viscosity, the fungal strains which
produce these PS, the PS themselves and their use.
It is an object of the present invention to
prepare nonionic homopolysaccharides having a hlgh specific
viscosity and high heat stability, salt stabill;ty and
long-term stability. Stability means that the molecular
`n 30 weight and hence the properties do not change significantly
under the (possibly simultaneous) influence of elevated
temperatures, salts and atmospheric oxygen.
More particularly, the invention relates to
the fungal strains DSM 3887, DSM 3888, DSM 3890, DSM 3891
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` and DSM 3892, which are deposited at the Deutsche Sammlung
!~ ' fur Mikroorganismen IDSM), Gottingen.
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- 2 - O.Z. 0960/32003
We have found that this object is achieved if
microorgan;sms in the form of the fungal strains stated
in claims 1 and 2 are cultivated in a nutrient medium with
aeration and agitation at from about 15 to 40C and are
then heated for from 2 to 30, preferably from S to 15,
minutes at from 70 to 90C, preferably from 75 to 85C, if
the fungal strains have matured, the culture solution is
i then seParated from the cell mass, and the resulting
-~ homopolysaccharide is isolated therefrom with a purity o~
-~ 10 greater than 99~ from 0.03 to 0.1~ by weight of residual
- protein and with virtually only glucose as a basic monomer
component.
rhe conventional nitrogen and hydrogen carbon source
~hich can be assimiLated by the fungal strains, and the
` 15 inorganic ions required for growth, are made available to
the fungal strains as a nutrient medium, advantageously in a
concentration such that, when the cultivation is terminated,
the residual concentration of the carbon source is of the
order of 0.1X by weight, based on the total solution. The
nonionic PS produced have a viscosity of from 50 to 190
mPa.s at a shear rate D of 0.3 s 1 at 40C, determined with
0.3 9 of PS dissolved in 1,000 ml of highly saline water
(containing up to 1ûO g/l of alkali metal ions and up to 30
i~` g/l of alkaline earth metal ions). This viscosity remains
virtually constant for 1 year or longer at 60C in the air.
In the absence of oxygen, this even applies at temperatures
up to 90C. The viscosity of the nonionic PS produced
i according to the invention is influenced only to a small
~-~ extent at a concentration of from 0.1 to 1 g/l at about 20-
60C and in the shear range D of about 3 0 s 1 or higher,
so that it may be regarded as constant for practic!al
purposes. Even after a solution containing 0.3 g/l of the
PS obtainabLe according to the invention has been heated
for one hour in an autoclave at neutraL pH and at 120C
under 1 bar g3ge pressure, viscosity re~ains virtually
unaffected in the shear range D from 0.1 to 300 s 1 after
cooling to 20C and supple~enting the evaporated ~ater. The
~' .
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. . .
^` 132915~
_ 3 - o.Z. 0960/02003
PS consist of a linear chain of 1,3-bonded ~-D-
glucopyranose un;ts subst;tuted to different degrees by
1,6-bonded ~-D-glucopyranosyl groups.
~or use, the fungal strains are advantageously
immobilized in a conventional manner on a substrate, pre-
~ ferably a polyurethane foa~, and the formation of the PS
is carried out semicontinuously or completely continuously
using this immobilized material.
The PS obtainable according to the invention are
very useful as viscosity-increasing agents in polymer and
; surfactant flooding of oil deposits, as dispersants or
emulsifiers (alone or in combinat;on with anionic and/or
nonionic surfactants), as thickeners possessing structural
viscosity, as water retention agents and for improvin~ the
adhesion of substances to solid surfaces. ~hen employed
as thickeners, they are intended in particular for use in
drilling muds, for secondary and tertiary flooding of oil
deposits and in general for reducing frictional resistance
in flo~ing, in particular turbulent, aqueous liquids in
order to reduce the pressure loss. Examples of suitable
applications as dispersants are in agricultural chemicals,
such as fungicides and pesticides, and in the food and
animal feed sectors.
The fil~ration properties of the PS produced ac-
cording into the invention, as an e~pression of the inject-
ability into porous med;a, such as oil-bearing rock, are
outstanding. For a sa~ple of 0.3 9 of PS per l of highly
sal;ne ~a~er containing up to 100 g/l of alkali metal ions
and up to 30 9/~ ~f alkaline e~rth me~al ions and pressure
filtration under one bar gage pressure over a 3 ~ me~brane
`; filter of 19 cm2, using 200 ml of solu~ion, the relevant
properties are from 0~5 to 3.0 ~in in the case of shearing
for 5 sec and from 078 to 10 min ~ithout shearing; the cor-
responding propert;es for filtration over a 1.2 ~ me~brane
filter are from 1.6 ~o 18 min in ~he case of shearing for 5
sec and from 4.0 to 14 min without shearing.
The sus~ension Gulture is grr~n for about iû-1aû,
1 32q 1 5~
- 4-- O.Z. 0960/02003
preferably 50-80, hours.
rhe noveL process gives the PS directly in very
pure form. The resiclual protein content is from about
0.03 to Q.1X by weight.
For the purposes of the present invention, water-
soluble means that not less than 1, preferably not less
than 20, 9 of PS are soluble in a liter of water at Z0C.
In spite of their high molecular weight, the novel PS are
water-soluble because they are substituted to a high deg-
ree by side chains. They differ from the polysaccharides
~?~,~ described in U.S. Patent 3,301,848 in that, inter alia,
they have a substantially higher molecular weight. rheir
superior properties are mainly due to this.
The preferably used microorganisms in the form
of fungal strains are characterized in the Tables below.
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- 5 - O.Z. 0960/02003
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~ 1329159
. - 6 - 0. Z. 0960/02003
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; ~ 1 329 1 59
- 7 - o.Z. 0960/02003
Typical viscometric data for characterizing the polysac-
charides
AW
106 110 114 115 116 117
"
~u ~mPas~187 81 188 51 163 144
n 0.1 -0.150.06 O.t2 0.15 0.13
C~] r~l/g] 6200091000 17000 - - 43000
M~ Cg/mol] 22.5x106 9x1o68X106 - _ 6
DP 139000 5500050000 - - 105000
1 0
~- n = Zero shear viscosity of an aqueous PS soLut;on
ontaining 0.3 g/l
' n = Flow behavior index
~ .~.,
C~] = Intrinsic viscosity. This gives the space require-
` 15 ment of a polymer coil in dilute solution (<=0.5 g/l)
; and is directly related to the molecular ~eight
via the Mark-Houwink equation n = K.M~a
MW = Molecular weight
DP = Degree of poly~erization M~/162
16Z= D-glucose - 1 H2O
`:
The Examples ~hich follow illustrate the invention.
; EXAMPLE 1
Preparation of a ho~opolysaccharide, type AW 106, using
the fungal strain DSM 3889O
Two slant agar cultures of the strain DSM 3A89
~ere suspended in 3 ml of 0.9X strength sodium chloride
solution, and this suspension was used to inoculate
~,~ 500 ml of a nutrient solution containing 1.5 9 of NaN03,
30 0.5 9 ot K2HPO4 3 HzO, 0.25 g of MgS04 . 7 H20,
O.Z5 g ot KCl, 1.0 9 of yeas~ extract and 5.0 g o~ glu-
cose. The shaken suspension culture ~as cultivated at
~I 27C for 60 hours at pH 4.5. The preculture thus pre-
;~ pared ~as used to inoculate a 15 l bioreactor equipped
with three six-blade disk stirrers and containing 10 l
of a culture neuiun having the folLo~in~ cor,position:
,
1329159
- 8 - O.Z. 0960lOZ003
NaN03 30 9
K2HP04 3 H2013 g
MgS04 . 7 H2O 9
KCl - 5.0 9
ZnSO4 7 H200 03 9
Citric acid . H20 7.0 9
Glucose 300.0 9
Cultivation was carried out for 80 hours at 27C
~ith stirring at 500 rp~ and aeration with 1.67 liters of
sterile air per liter of nutrient medium per minute and
at an initial pH of 3.5. During the cultivation, the pH
decreased to 2.7. After the end of the cultivation, the
residual glucose content was less than 0.1% by ~eight.
The culture suspension was heated at 80C for
30 ninutes, diluted ~ith 50 l of deionized water and cen-
trifuged at 15,ûO0 9. The polysaccharide A~ 106 was pre-
cipitated from the supernatant liquid with ;sopropanol
(volume ratio 1:1), filtered off and washed ~ith 70Z
strength aqueous isopropanol solut;on, and the precipitate
~as resolvatized in 1 l of deioni~ed water and freeze-
dried. 120 9 ot polysaccharide A~ 106 were obtain@d. The
product contained glucose, as a ~onomer building block, and
less than 0.05~ by weight o~ protein. 0.3 9 of AW 106
dissolved in 1,000 ml of formation water tcomposition in
g/l: CaCl2 42.6 MgCl~ 10.5, NaCl 138.0, Na2S04 1.2 and
Na802 . 4 H2O 0.4) had a viscosity of 137.7 mPa.s at a
shear rate of 0.3 s 1 and 40C.
EXAMPLE 2
Preparativn of a homopolysaccharide, type AW 110~ using
the fungal strain DSM 3887.
Four slant agar cultures of the stra;n DSM 3887
were suspended in 3 ml of O.9X strength sodium chloride
~ solut;on, and this suspension ~as used to inoculate
;l 35 1,000 ~l of a nutrient salt solution containing 1.0 9 of
KzHP04 . 3 H2O, 1.5 ~ of KCl, 1~5 9 of N~NO3, 0.5 9 o~
MgSO4 . 7 HzO, 0.5 g gf yeast estrsct and 10.0 9 of glucose.
.
:
~ 1 329 1 59
- ~ - O.Z~ 0960/02003
The shaken suspension culture was cultivated at 27C for
54 hours at pH 4.5. This inoculation culture was used to
inoculate a 70 l bioreactor equipped ~ith an Intensor~
System fr-om Giovanola, Monthey, Switzerland, and con-
taining 50 l of a nutrient medium having the follo~ing
` composition:
NaN03 75 9
~; KCl 75 9
K2HPo~ 3 H2O
10 MgS04 7 H20 25 9
FeSO4 . 7 H2O2.5 9
Xylose 1500.0 9
Cultivation ~as carried out for 96 hours at 27Cith stirring at 1,Z00 rpm and aeration with 0.5 liter
of sterile air per liter of nutri~nt medium per ~inute,
at an initial pH of 4.5. After the end of the cultivation,
the pH had decreased to 3.0 and the xylose was virtually
-~ compLetely consu0ed.
~; The culture medium was heated at 85C, and the
2Q cell mass ~as separated off at this temperature by means
of pressure filtration. The clear, highly viscous fil-
~ trate was precipitated with iscpropanol and freeze-dried,
;1 as described in Exa~ple 1. 435 9 of the homopolysaccharide
type AW 110 ~ere obtained. The product contained exclu-
sively glucose as the basic monomer component and had a
residual protein content of less than 0.03~ by weight.
-~ Elemental analysis gave the following composition:
Carbon: 44-5~
Hydrogen: ~.25%
; 30 Nitrogen: 0~005~
0.3 g of A~ 110 in 1,000 ml of for0ation ~ater
in oil production, having the composition according to
~ ,:
Example 1, had a viscosity of 81.6 0Pa.s at a shear rate
~` of 0.3 s 1 and 40~C.
EXAMPLE 3
Preparation of a ho~opolysaccharide, type A~ 114, using
q the fungal strain DSM 3888~
,
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1 329 1 59
- 10 - O.Z. 0960/02003
T~o s~ant agar cultures of the strain DSM 3888
were suspended in 3 ml of 9% strength sodium chloride
solution~ and this suspension ~as used to ;nocuLate
500 ml o~ a nutrient salt solution containing 3.0 9 of
yeast extract, 0.75 9 of (NH4~2HP04, 0.5 9 of K2HP04 . H20,
-0.25 9 of MgS04 . 7 H20 and 10 9 of glucose. The shaken
suspension culture was cultivated at 27C for 96 hours at
pH 5.3. The pellets formed ~ere homogenized using an
Ultra-Turra~Q stirrer at 20,000 rpm for 10 seconds, and
this homogeni~ed innoculation culture was used to inoculate
a 15 l bioreactor equipped ~ith three si~-bLade disk stir-
rers and containing 10 l of a nutrient medium having the
- following composition:
.~ Technical-grade yeast extract 30.0 9
15 K2HP04 . 3 H20 10.0 9
MgS04 . 7 H20
Xylose Z50.0 9
Cultivat;on was carr;ed out for 76 hours at 27C
~;th stirr;ng at 400 rpm and aeration with 0.1 Liter of
~ 20 sterile a;r per l;ter of nutrient mediu~ per minute, at
- an initial pH of 5.3. After the end of the cultivation,
the pH had decreased to 4.6 and the residual xylose con-
tent was 0.1% by weight.
The react;on mixture was heated to 80C, 10 9 of
formaldehyde were added, and the predominant amount of
the polysaccharide ~as liberated from the resul~ing pel-
~i Lets by shearing with an Ultra-Turrax for 10 seconds at
Z0,000 rp~. Thereaf~er, the cell ~ateriaL ~as separated
off by pressure f;ltrat;on, and the clear f;ltrate was
freed from lo~ molecular we;ght substances by ultra-
-- f;ltration at an exclusion limit of 100,000 Dalton'. The
uLtrafiltraee ~a~ prec;pitated w;th isopropanoL and
freeze-dried, as descr;bed in Example 1. 7Z g of a ho~o-
polysaccharide A~ 114 were ob~a;ned. The product contained
excLusively gLucose as ~h~ basic monomer component and had
a res;dual protein content of less than 0.05X by we;ght.
Ele-ent~l analysis gs~e the foLLowing co-position:
132~15q
- 11 - O.Z~ 0960/02003
Carbon: 44.42%
~- Hydrogen: 6~19%
Nitrogen: 0.01X
.3 9 of A~ 114 dissolved in 1,000 ml of forma-
tion water having the composit;on described ;n Example 1
had a viscosity of 188.7 mPa.s at a shear rate of 0 3 5 1
and 40C.
EXAMPLE 4
Preparation of a ho~opolysaccharide, type AW 115~ using
the fungal strain DSM 3890.
A slant agar culture o~ the strain DSM 3890 was
; suspended ;n 3 ml of 0.9~ strength sodium chloride solu~
tion, and this suspension ~as used to inoculate 100 ~l
of a nutrient salt solution conta;n;ng 0.1 g of yeast
e~tract, ~.1 9 of K2HP04, 0.5 9 of MgS04 . 7 H20 and
1.0 9 of glucose. The suspension culture ~as cultivated
at 25C for 60 hours at pH 5.7, ~h;le shaking on a rotary
shaking ~achine at 110 rpm. This preculture was used to
inoculate t~o 2 l conical flasks, each of which contained
500 l of nutrient medium having the following composition:
K2HP04 3 ~2 9
MgS04 7 H20 0.25 9
Yeast extract 0.5 9
Glucose 12.0 9
25 After incubation at Z5C on a rotary shaking
machine at 110 rpm and at a pH of 5.7, the spec;fied
amount of glucose was consumed after 142 hours and a pH
of 3.5 reached. The two batches were combined and dilu-
ted ~ith 5 l of deionized water, and ~he cell mass was
separated off by centrifu~ing. The clear supernatant
liquid ~as concentrated to a polysaccharide content of
4.3 g/l by ultrafiltration at an exclusion limit of
100,000 Dalton~ the lo~ ~olecular weight components
simultaneously being separated off. Ethanol was added to
the concentrate (volume ratio 1:1), and the prec;pitated
polysaccharide A~ 115 was separated off by centrifuging~
~ashed ~ith ~00 ml of 70~ strength ethanol and free2e-
~ ~' 1329159
- 12 - O.z. 0960/OZ003
dried. 5.05 9 of polysaccharide AW 115 were obtained.
This product contained exclusively glucose as the mono-
mer building block and 0.11% by weight of protein as an
accompany-ing substance, the percentages being based on the
; 5 polysaccharide content.
0.3 9 of AW 115 dissolved in 1,000 ml of for~mation
~ater (for composition, see Example 1) had a viscosity of
51 mPa.s at a shear rate of 0~3 s 1 and 40C.
EXAMPLE 5
Preparation of a homopolysaccharide, type AW 116~ using
the fungal strain DSM 3891.
`~ Starting from a slant agar culture of the fungal
strain DSM 3891, the ho~opolysaccharide AW 116 was pro-
duced under the sa~e conditions as described in Example
4. However, 50 9 of maltose/l of nutrient medium ~ere
used as the C source. The cultivation was terminated
after 120 hours, when a pH of 3.6 had been reached and
the res;dual content of maltose had decreased to û.1~ by
eight.
The mixture was worked up as described in Exa~-
ple 4 to gi~e 4.0 9 of homopolysaccharide containing less
than 0.05~ by ~eight of proteinsu 0.3 g of A~ 116 dis-
solved in 1,000 ~l of formation water having the co~posi-
~` tion described in Example 1 had a viscosity of 163.2 mPa.s
25 at a shear rate of 0.3 s 1 and 40C.
EXAMPLE 6
Preparation of a homopolysaccharide, type A~ 117, using
the fungal strain DSM 3892.
Two slant agar cultures of the strain DSM 3892
~. .
were suspended in 3 ml of 0.9% strength sodiu~ chloride
solution, and this suspension was used to inoculate
500 ~l of a nutrient salt solution containing 0.5 g of
yeast extract, 0O5 g of K2HPO4 . 3 H2O, 0.25 9 of
~gS04 . 7 H2O, 0.25 g of citric acid-H20 and 5 9 of suc-
}5 rose. The suspension culture was cultivated a~ 25C for
72 hours at pH 5.6, ~hile shaking on a rotary shaking
~achina ae 100 rp~. This preculture ~as used to
.'
. ~
t 329 1 59
- 13 - O.Z. 0960/02003
inoculate a 15 l bioreactor which was equipped with a guide
tube possessing a propeLler stirrer and contained 10 l of
nutrient medium having the following composition:
K2HP04 ~3 H20 10.û 9
S MgS0~ . 7 H20 5.0 9
Yeast extract 5.0
Asparagine 12.0 9
Glucose 33U.0 9
Cultivation was carried out for 48 hours at 25C
; 10 ~ith stirring at 6ûO rpm and aeration w;th 1.0 liter of
sterile air per liter of nutrient medium per minute, at
an initial pH of 5.6. After the end of the cultivation,
the pH had decreased to 3.2 and the residual glucose con-
- tent was 0.15% by weight.
8 1 of deionized water ~ere added to the culture
medium, the mixture ~as heated to 85C and the cell mass
was separated off by means of pressure filtration. The
clear cultur~ solution was concentrated to a homopoly-
saccharide content of 10 g/l by ultrafiltration at an ex-
clusion Limit of 100,000 Dalton, and was free2e-dr;ed.
90 9 of homopolysaccharide A~ 117 were obtained.
After hydrolysis of the production in 6 N H2S04
at 90C under an N2 atmosphere, glucose was detected
as the only monomer component by thin layer chromatography
and by high pressure liquid chromatography.
Elemental analysis gave the follo~ing composition:
Carbon: 44.32X
Hydrogen: 6.21X
Nitrogen: 0.09~.
This gives a residual protein content of 0.56%.
0.3 9 of A~ 117 dissolved in 1,000 ml of forma-
tion ~ater according to ExampLe 1 had a viscosity of
144.5 mPa.s at a shear rate of 0.3 s 1 and 40C.
In order to test the suitability of the PS pro-
duced by the process of the invention for tertiary oilproduction, the fungal strains stated ;n cLaim 1 ~ere
grown in submerse culture, subjected to pressure
~ 1 32q 1 5q
`:
- 14 - O.Z. 0963/Q2003
filtration and substantially freed from inorganic ions,
residual glucose and proteins by subsequent ultrafiltra-
- tion at an exclusion limit of 100,0ûO Dalton. Formalde-
- hyde was-added to this stock solution as bactericide
and as a stabilizer.
~ The follobing evaluation criteria were checked
using these stock solutions:
The viscosity in formation water having the com-
;~ position according to Example 1, with a total salinity
of 190 g/l.
The polymer concentration was adjusted so that,
-~ for industrial use at from 40 to 60C, the viscosities
were fro~ 30 to 40 mPa.s at a shear gradien~ D of 0.3 s 1.
~; The ~iscosities at D = ~.3 s 1 and D = 3.0 s 1 were used
for characterizat;on.
The data in the Table below shou that 0.3 g/l of
the homopolysaccharide solutions produced are sufficient.
It is found that the speci~ic viscosity at 60C is higher,
and the temperature dependence smaller, than in the case
of the com~ercial products used for compar;son.
- The Table shows that at, for e~ampLe, 40C, 1 g/l
of Flocon~ 4800 have to be used, compared with only
; 0.3 g/l of the PS type AW It4 obtainable according to
; the invention, in order to obtain similar viscosities.
Evaluation ot the Table also shows that, owing
to its pronounced temperature dependence, the sa~e com-
~ercial product cannot be used at a temperature above 60C.
In contrast, the viscosity of the homopolysaccharide
obtained by the process of the invention exhibits little
te~perature dependence.
,
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r~ 1 329 1 59
- 15 - O.Z. 0960/02003
Viscosity
n tmPa.s] Shear Concent-
gradient ration
Product ~) T - 25C 40C 60C
`` 5 A~ 114 74 53 44 0.3 0.3
`;~ 30 -26 22 3.0
A~ 117 48 39 27 0.3 0.3
i~ 24 20 16 3.0
;~ Actigu ~ 20 13 8 0.3 0.3
; 10 12 9 7 3.0
Actigum 80 50 32 0.3 0.5
: 38 30 2~ 3~0
Flocon~34800 - 42 18 0.3 1.0
34 14 3 0
.: 15 +) The solutions of the products are each sheared under
. the same cond;tions.
The commercial product Actigum has to be used in
~;: an amount of 0.5 g/l in order to obtain a viscosity of
30-4Q mPa.s at D = 0.3 s 1 and at T = 60C. In contrast,
`.- 20 only 0.3 g/l of the product prepared by the process of
A~ the invention, type A~ 114, has to be used.
:i: Filtration behavior:
;:
As a technical rule, the solutions of the homo-
; polysaccharides should flo~ freely, ~ithout causing bLock-
.: 25 ages, through a filter having a pore diameter Dp of 1.2 ~m.
200 ~l of the solutions of the homopolysaccharides are
filtered through a filter having a diameter of 47 mm, under
a pressure of 0.4 bar. The ratio of ~he fLow rate of the
first fourth to the fourth fourth is the ~illipore filter
ratio ~MPFR). Solutions ~hich can readily be filtered
~; have an MPFR value of less than 106u This filtra~ion
behavior can be further improved by subjecting the stock
so~utions to shear forces.
; The Table belo~ gives the data for ~he viscosities
and the filtration of the PS produced by the process of
the inventir,n using the fungal streins according to clail 1.
,
1 ~29 1 59
- - 16 - O.Z. 0960/02003
The types
AW: 106, 110, 114, 115~ 116 and 117
correspond to the fungal strains
DSM: 388Q, 3887, 3888, 3890, 3891 and 3892.
. S n 0.3 and n 3.0 are the viscosi,ties at shear rates
of 0.3 and 3.0 s 1, respectiveLy.
MPfR = millipore filter ratio
Dp = pore diameter
~ Conc. = concentration in g/l
,,, 10 The solvent used ~as formation water according to Ex'ample
.~ 1.
The shear conditions are:
,- 7,000 rpm x 3 min in an Ultra Turrax circu,lation appara-
~ tus from Janke & Kunkel, Staufen~ FederaL RePublic of
'~ 15 Germany.
'~ - = Not subjected to shearing
, + = Subjected to shearing.
'~ All solutions are filtered ~ith 3 ~m or 5 ~m me~brane
,, filters. The viscosities after filtration are measured
,' 20 at T = 25C and expressed in mPa.s.
~,~
' Homopoly- A~ 106 AW 110 A~ 114
; saccharide = + - ~ - *
n 0~3 46 57 31 118 74
,j 25 n 3-0 18 26 18 32 30
MPFR 1.4 1.3 1.2 1.0 1.0
~, Dp C~ 1. 2 3 1. 2
Conc. ~g/lJ _ 0.3 0~3 - 0'3
;~ 30
, Homopoly- A~ 115 AW 116 AW 117
saccharide - +
J , _ , _
n 0.3 121 73 181 79 133 48
3.0 30 30 3~ 34 29 24 -
MPfR 1.5 1.81.8 1.6 1.16 1.0
,; Dp C~m] 1.2 1.2 1.2
Conc. [~/l] ~,4 0.3 0.3
,.
.
.
t 329 1 59
- 17 - O.Z. 0960/02003
The Table shows that types AW 114 and AW 117 can
very readily be filtered even without being subjected to
shearing. As a result of shear;ng, the v1scosity is pre-
ferentiaL-ly reduced at the lower shear gradient of D =
0.3 s 1 This results in a flattening of the viscosity
curve, and this measure enables the viscosity to be~
adjusted.
`~ Long-term stability:
Solutions subjected to shearing and filtered for
'- 10 use in practice were used to check the long-term stability
`~ of the viscosity at T = 40C, 60C and 85C, different
solutions stabilized with 200 or 1,000 ppm of formaldehyde
being employed in the presence and absence of oxygen
(2)-
~' 15 Type AW 114 is stable, for example at 60C~ for
;~ 1 year or longer. This result is also found, for example,
for type AW 117. These two solutions of the homopoly-
saccharides were stabilized with formaldehyde but were not
free of oxygen.
An important characteristic for practical use is
j the filtration time of the PS obtainable according to the
invention. The Table below shows the filtration times
in ~inutes using ~embrane filters having pore diameters
.~
of 1.2 ~m and 3 ~ and a filter dia~eter of 47 m~. To
,t~ 25 determine the filtration property, 0.3 g/l of PS is dis-
~~ solved in formation water according to Example 1 and the
solution is filtered over the membrane filters under 1 bar.
` The time, in minutes, required for the filtration of 200
`~ ml is determined.
3~ D;fferent filtration times are obtained. Negative
solutions of types A~ 114 and A~ 117 possess good!filtra-
tion properties after uLtrafiltration without treatment
:,~
f by shearing. For good filtration properties, products
~; A~ 106, AW 110 an~ A~ 116 require treatment by shearing
for 5 seconds in a ~aring ~lendor in order to obtain an
industrially usable filtration ti~e.
~'l Type A~ 115 requires a longer filtra~ion time.
:,
: `
'` 1 ~2~ 1 5~
- 18 - O.Z. 0960/0Z003
Where a shorter filtration time is important for indus-
trial use, a longer shearing time will be required. The
preferred types of the homopolysaccharides prepared by
the proc~ss of the invention make it possible to prepare
S products having the filtration times reyuired for indus-
trial use.
Table showing the filtration times at 2 different pore
diameters of the membrane filters, in minutes
3 ~m 1.2 ~m
10 Type ~min.] [min.]
AW 106 0.5 18.0
AW 110 3.0 12.0
AW 114 0.8 4.0
AW 115 10 14
AW 116 1.6 1.6
AW 11? _ _ _ 2.5 _ 4.5
Treatment by shearing for 5 seconds in a Waring ~lendor
The PS produced by the process of the invention
using microorganisms in the form of fungal strains accord-
ing to claim 1 have the advantage of good water solubility.
For this reason and because of their rheological proper-
, ties~ these products have a wide range of uses in indus-
try in the form of solutions~ as well as in the for~ of
, shaped materials or of films and filaments.
Other advantages are the heat stability, the
long-term stability and the shearing stability of the
solutions, as well as their controllable filtration pro-
perties.
