JPS635426B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for decomposing isoprene rubber using microorganisms. Conventionally, many studies have been conducted on the effects of microorganisms on so-called "vulcanized rubber products", which are made by adding sulfur, etc. to natural rubber to increase the strength of the rubber, with the aim of preventing deterioration of rubber packing for water supplies, etc., and there are also reports. many. but,
The reports to date have mainly focused on preventing the deterioration of rubber caused by microorganisms, and not on actively deteriorating or decomposing rubber products. Therefore, the time required for rubber to decompose is extremely slow, ranging from several months at most to several years at most. Therefore, the inventors of the present invention believe that if they can actively search for microorganisms that can decompose rubber products such as waste tires in a short period of time, it will be possible to apply them to pollution prevention and composting. As a result of searching widely for microorganisms with such ability in the natural world, we discovered that certain microorganisms among isolated strains can strongly and quickly decompose natural and synthetic isoprene-based rubber products, and we have completed the present invention. I've reached it. That is, the present invention belongs to the genus Nocardia or Rhodococcus and has a crosslinking density of about 4×10 ¹⁹ /cm ² or less, or an equilibrium swelling degree in benzene (25
Decomposition of rubber, characterized by culturing microorganisms capable of degrading and assimilating isoprene-based rubber products having a temperature of about 4 °C or more in a medium whose main carbon source is the rubber product, and decomposing the microorganisms. It is about law. The newly isolated strain is NR-
They were named 26S strain, NR-34A strain, and NR-35A strain, and have been deposited as Microtechnology Research Institute Deposit No. 7268, No. 7267, and No. 7266.

[Table] Use

[Table] Liquefaction

[Table] ±: Weak positive -: Negative Based on the above mycological properties, as a result of searching using Virgies, Manual 8th Edition, etc., the NR-26S strain is of the genus Rhodococcus, the NR-34A strain is of the genus Nocardia,
The NR-35A strain is recognized to belong to the genus Nocardia. The strain used in the present invention grows in a medium containing synthetic or natural isoprene-based rubber as the main carbon source, and as a general growth medium, for example, a synthetic medium consisting of the following inorganic salts is used. . Table 1 (NH ₄ ) ₂ SO ₄ 1.0g KH ₂ PO ₄ 0.2g K ₂ HPO ₄ 1.6g MgSO ₄・7H ₂ O 0.2g NaCl 0.1g CaCl ₂・2H ₂ O 0.02g FeSO ₄・7H ₂ O 0.01g NA ₂ MoO ₄・2H ₂ O 0.5mg Na ₂ WO ₄・2H ₂ O 0.5mg MnSO ₄ 0.5mg Distilled water 1 PH 7.5 For this medium, usually 50mg to 10g/100ml
Degrading microorganisms are then inoculated. Preferably, the solid rubber product is cut into long threads or strings, and the microorganisms are inoculated using a rotor or the like under shear stress or shear force. A method of contacting with microorganisms is adopted, or a method of scraping off the decomposed surface at regular intervals using an appropriate method and contacting it with microorganisms while constantly renewing the untreated surface. However, depending on the type of rubber product, may be contacted in the form of fine particles or a film as much as possible. In addition, the culture is usually carried out at 30°C for about 14 to 60 days, and is carried out with aeration, such as by stirring the culture. In general, the stirring speed affects the decomposition rate, so it is 600 to 1200 rpm.
A stirring speed of is selected. The isoprene-based rubber used in the present invention is a rubber product containing natural or synthetic isoprene-based rubber as a main component, and has a crosslink density of approximately 4×10 ¹⁹ /
cm ³ or less, or whose equilibrium swelling degree in benzene is about 4 or more, or may contain inorganic fillers such as charcoal or clay. . Examples of such rubber products include commercially available famous rubber bands, rubber bands,
Examples include rubber thread, rubber tubes, condoms, rubber balloons, and rubber gloves. By culturing these rubbers for two weeks to two months, it is possible to decompose and assimilate up to 100%. The present invention will be specifically explained below using Examples. Example 1 NR-26S strain (FERM-P 7268) NR-34A strain (FERM-P 7267) NR-35A strain (FERM-P 7266) One platinum loop was added to each, and 50 mg of commercially available rubber glove shreds were added. Add to 100 ml of the medium in Table 1 and store at 30℃ for 1 month.
The culture was stirred using a magnetic stirrer at 800 rpm.
The degree of decomposition of the rubber pieces was measured by weight loss, and the growth of bacterial cells was measured by the total protein content in the medium using a modified Lowry method. The results are shown in Table 2.

[Table] Crosslinking degree of rubber gloves used = 3.4 x 10 ¹⁹ /cm ³ Equilibrium swelling degree in benzene (25°C) = 4.9 Example 2 NR-35A strain 1 platinum loop containing 70 mg of the following various rubber pieces It was added to 100 ml of the medium shown in Table 1 and cultured with stirring using a magnetic stirrer at 600 rpm for 2 months at 30°C. The analysis was conducted in the same manner as in Example 1.

[Table] Example 3 1 platinum loop of NR-35A stock and 100 pieces of the following famous rubber pieces
Add to 100 ml of the medium in Table 1 containing mg, and keep at 30℃ for 1 month.
The culture was stirred using a magnetic stirrer at 800 rpm.
The analysis was conducted in the same manner as in Example 1.

[Table] Example 4 Table 1 containing 1 platinum loop of NR-35A strain and 270 mg of rubber band
The cells were added to 100 ml of the culture medium and cultured at 30°C for 2 months using various methods.

[Table] Example 5 Results of a test similar to Example 2 using the NR-26S strain. Weight loss Protein ring Rubber 98% 8mg Rubber tube 80% 12mg Rubber nipple 60% 6mg Rubber balloon 53% 6mg Condom 45% 3mg Example 6 Example 3 using NR-26S strain and NR-34A strain
Results of tests conducted in the same manner.

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Claims (1)

[Claims] 1 Belongs to the genus Nocardia or the genus Rhodocotcus,
It has the ability to decompose and assimilate synthetic or natural isoprene-based rubber products with a crosslink density of about 4×10 ¹⁹ /cm ³ or less or an equilibrium swelling degree in benzene (25°C) of about 4 or more. A method for decomposing rubber using microorganisms, which comprises culturing microorganisms in a medium containing the rubber product as a main carbon source and decomposing the microorganism.