HU183596B - Process for preparing xanthane gum by means of a xanthomonas pruni strain or of variants thereof - Google Patents

Abstract

A new process for the industrial production of xanthan rubber as a carbon source in sucked-aerated conditions at 25-30 ° C in sucrose and / or glucose and / or hydrolysed starch and / or fructose, organic nitrogen source in maize corn and / or soy extract and / or animal protein containing fluid. 6.5-7.5 using Xanthomonas pruni (OKI 00191) for fermentation, and the xanthan gum formed during culture is isolated from the fermentation broth by means of organic solvent precipitation in a manner known per se, dried and then pulverized. Xanthan rubber is widely used in agriculture and industry as a thickener and / or stabilizer.

Description

The present invention relates to a novel process for the industrial production of xanthan gum, wherein the strain Xanthomonas pruni isolated by us and deposited with the National Institute of Public Health and its derivatives are sucrose and / or glucose and / or hydrolyzed starch and / or fructose as carbon sources. , preferably cultivated on a liquid medium containing corn jam and / or soy extract and / or animal protein and mineral salts under immersed aeration, maintaining the temperature at 25-30 ° C, pH 6.5 by addition of acid or base It is maintained at -7.5, and the xanthan gum formed during culturing is isolated from the fermentation broth in a manner known per se, preferably by isopropyl alcohol precipitation, and then powdered.

Xanthan gum is a high molecular weight heteropolysaccharide with colloidal properties. Its solution is already high at 1% concentration and has a viscosity of 1500-2000 mPas. (Measurement conditions: RHEOTEST-2 rotary viscometer, set at 9.00 sec ^-1 shear stress at 25 ° C.) This high viscosity is used in industrial applications to stabilize suspensions, emulsions. U.S. Patent Nos. 3,507,664; 3,573,972; 3,784,201; 3,821,008.

The industrial production of xanthan gum is done using microorganisms, primarily Xanthomonas species. Particularly preferred are strains of Xanthomonas campestris (US Patent 3455786; 3485719) and Xanthomonas vesicatoria (Hungarian Patent Application No. 166072).

In different processes for the production of xanthan rubber, different factors prevailed as aspects of progress. These include, for example, the amount and quality of the xanthan gum formed, the minimum fermentation time required, the amount of sugar used to produce the unit amount of xanthan gum (degree of conversion), the most solvent-efficient, and thus most economical, method of recovering the polysaccharide.

According to literature data, the highest available concentration of xanthan gum in fermentation broth is 3.6% w / v (Hungarian Patent No. 166072). For fermentations with a maximum yield of 2.5% to 3.0%, the growing time is usually 48 to 96 hours (3485719; U.S. Patent 3455786; Journal of Hungarian Chemists 35/98, 468-74, 1980).

Xanthan rubber is widely used in agriculture and industry as a thickener and / or stabilizer.

From the economical point of view, it is very important how much sugar is used by the microorganism to produce 1 kg of xanthan gum, i.e. the degree of conversion. This is on the one hand from the producing strain [e.g. in the case of a Pseudomonas, only 30% of the sugar ingested was converted to polysaccharide (French Patent No. 2378092)] and, on the other hand, depends on the composition of the medium and the culture conditions.

It is relatively easy to achieve a high degree of conversion without also considering high xanthan rubber production. Both conversion rate and xanthan gum production are highly dependent on the sugar content of the medium, but the opposite is true. This is well illustrated in U.S. Patent No. 4,071,406:

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broth sugar content, vo The amount of xanthan produced, % conversion degrees, vo 0.5 0.45 90 1.0 0.78 78 2.0 1.55 78 3.0 1.88 63 4.0 1.90 48

Xanthomonas vesicatoria strain provides the highest degree of conversion and at the same time the highest amount of xanthan gum by providing the process with Xanthomonas vesicatoria strain, providing 3.6% w / v xanthan gum production with 72% conversion rate in the fermentation broth glucose using a carbon source; with the use of sucrose at 25, production is lower.

Achieving a high degree of conversion and the quality of the carbon source to be utilized is very important for the profitability of xanthan rubber production.

From this point of view, it is significant to realize that our isolated strain Xanthomonas pruni with accession no. volume%.

3 ₅ also has the advantage of using our newly isolated Xanthomonas pruni strains that have a high conversion efficiency and high content of xanthan gum is available for the carbon source is sucrose. Xanthomonas vesicatoria strain for a given carbon source is sucrose ₄₀ Rás low production results.

Examining the molecular weight composition of xanthan rubber samples, it was found that about 20% of the amount of xanthan rubber produced by Xanthomonas pruni strain number 00191 is in the 5 million or more molecular weight range, compared to xanthan rubber samples from the Xanthomonas vesicatoria strain. only 8% of the product is in the molecular weight range above 5 million.

Higher molecular weight means higher viscosity, which results in more economical and wider industrial usability of our product.

Characterization of the strain: The strain was isolated in 1977 from market fruit waste. The strain shows growth characteristic of Xanthomonas on solid complex 55 media. The body of the bacterium is short, straight rod-shaped, and its movement is provided by a polar butterfly. Gram-negative, no spore formation. In complex media, where the medium contains carbohydrates, after 30 to 60 hours incubation, a significant amount of xanthan gum is produced. Dispenses gelatin. It does not utilize xylose, mannose, arabinose, maltose, raffinose, mannitol. Glucose, sucrose, fructose is polymerized and fermented into xanthan gum. Depending on the environmental conditions, glucose and sucrose are generally 80-85%

-2183596 turns xanthan rubber with efficiency. It does not reduce nitrate. A particular property of the strain is its ability to utilize sucrose in high-pressure culture in submerged culture.

The implementation of our procedure is illustrated below:

700 L working volume fermentor pilot plant using 2.1 kW / m ³ mixer-power deposited under number 00191 Xanthomonas pruni strains were grown at 25 ° C for 24 hours, the following aqueous medium:

corn steep liquor 1.6% peptone 0.5% glucose 1.0% Dipotassium hydrogen phosphate 0.1% sunflower oil 0.1% 1: 1 aeration at the end of the growing season

a viscous pre-fermentation culture was prepared from xanthan gum.

From the pre-fermentation obtained above, the main fermentation was inoculated with 70 liters of culture and used in a 700 liters fermentor using a 2.5 kW / m ³ energy mixer with a 1: 1 aeration and a pH of 6.5 to 7.5 at 28 ° C. at 50 hours.

The composition of the aqueous medium was as follows:

ammonium chloride, 0.1% dipotassium hydrogenphosphate 0.5% magnesium sulfate 7 H ₂ O 0.05% Sunflower oil 0.1%

In our experiments, the basic medium was supplemented with carbon and nitrogen sources of various qualities and amounts as shown in Tables 1 and 2. These tables also report the production data obtained by precipitating, drying and powdering 1 to 1 liter of fermentation leaves prepared according to the media compositions described in the tables using 1.5 times the volume of isopropyl alcohol.

Table 1 (using 1.6% corn jam as nitrogen source)

coal source denomination % produced by xanthan rubber conversion % its weight % viscosity mPas glucose 2.0 1.60 1930 80.0 glucose 3.0 2.55 1800 85.0 glucose 4.0 3.40 1550 85.0 glucose 5.0 3.20 1140 64.0 glucose 6.0 2.10 980 35.0 saccharose 2.0 1.55 2150 77.5 saccharose 3.0 2.40 2030 80.0 saccharose 4.0 3.35 1900 83.75 saccharose 5.0 3.00 1350 60.0 saccharose 6.0 1.85 1100 30.8

Table 2 Conversion of nitrogen source (using 4% sucrose as carbon source) to xanthan gum

denomination % its weight % viscosity ntPas % corn steep liquor 0.8 2.10 2050 52.5 corn steep liquor 1.6 3.35 1900 83.75 corn steep liquor, 2.4 3.00 1380 75.0 soybean extract 1.80 2100 45.0 peptone 0.1 2.80 2150 70.0 peptone 0.3 3.30 2100 82.5 peptone 0.5 3.30 1980 82.5

Patent claims

Claims (2)

1. A process for the industrial production of xanthan gum by culturing a bacterium of the genus Xar.thomonas, characterized in that, for fermentation, Xanthomonas 30 pruni strains (OKI 00191) are used as a carbon source in a liquid medium containing sucrose and / or glucose and / or hydrolyzed starch and / or fructose, organic nitrogen source in cornmeal and / '/ brain soy extract and / or animal protein. Under immersed-aeration conditions at 25-30 ° C at pH 6.5-7.5, the xanthan gum formed during culturing is isolated, dried and powdered in an organic solvent by precipitation in an organic solvent. 2. The process according to claim 1, wherein the medium contains from 2% to 6%, preferably 4%, of carbon sources. 45 3. A process according to claim 1, wherein 0.8 to 2.4%, preferably 1.6% of corn jam and / or soy extract is used as protein source in the medium. 50 4. Figures 1-3. The process according to claim 1, wherein the organic nitrogen source in the medium is 0.1-0.5%, preferably 0.3% animal protein. ₅₅ 5. Figures 1-4. Process according to Claim 1, characterized in that isopropyl alcohol is used for the precipitation in a ratio of 1: 1 to 1: 3, preferably 1: 1.5, by volume of the fermentation broth.