JPH10244294A - Method for bio-denitrification of hardly removable aromatic organic nitrogen compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform two phase denitrification reaction of petroleum org. solvent/water system for decomposing and removing different arom. org. nitrogen compd. with carbazole skeleton and quinoline skeleton with one kind of microorganism by bringing continuously a resting bacillus of a microorganism for decomposing an arom. org. nitrogen compd. into contact with a substance contg. the arom. org. nitrogen compd. and decomposing them. SOLUTION: By using a bacterium isolated from the natural world by an accumulation cultivation method under a barely aerobic condition with an oxygen partial pressure condition being at most explosion limit and with assimilation and decomposition ability under an appropriate water content by using carbazole as a sole nitrogen source and a sole carbon source, quinoline which is another representative compd. with a skeleton as a hardly removable arom. compd. except carbazole is also assimilated and decomposed. From a view point for decomposing efficiently, e.g. the interface for bringing the denitrification bacterium into contact with the org. nitrogen compd. as a substrate is enlarged by using a surfactant and stirring appropriately the reaction system. As the result, the reaction in a petroleum fraction such as a crude oil and kerosene can be done in two phases of a petroleum org. solvent/water and a resting bacillus can be repeatedly used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for denitrification using microorganisms. More specifically, using a specific strain,
The present invention relates to a method for denitrifying petroleum (product) such as crude oil and a substance containing an aromatic organic nitrogen compound such as coal.

[0002]

2. Description of the Related Art The demand for oil in the world is still resilient due to the necessity of revitalizing the industry worldwide, increasing consumption in developing countries, halting the development of alternative energy to oil, and the limit of energy saving. In particular, demand for gasoline, kerosene, and gas oil is strong, and the structure of petroleum demand is rapidly moving toward lightening. With the increasing demand for light petroleum, further progress and development of petroleum refining technology are desired.

[0003] For example, it is desired to establish a petroleum refining technology that responds to recent environmental problems and requires less burden on the environment. In the industry, there is an opinion that "in boiler combustion, it is necessary to select a high-quality fuel with low nitrogen content", and the need for denitrification is increasing. Also, from the viewpoint of preventing environmental pollution, it is desired to reduce the nitrogen content in light oil and kerosene due to NOx regulations and difficulty in obtaining light crude oil. It has been pointed out that nitrogen compounds in these fossil fuels become NOx by combustion, and as a result, one of the causes of acid rain, which is a major environmental problem. Furthermore, among the nitrogen compounds contained in crude oil and the like, there are also difficult-to-removable aromatic organic nitrogen compounds such as carbazoles. There are problems such as coloring of products.

[0004] In addition, the current purification technology centering on distillation and chemical reaction has been completed in one aspect, but it is an energy-consuming process that requires setting operating conditions of high temperature and high pressure. Under such operating conditions, there is a problem with respect to energy load and safety. Therefore, establishment of a means that does not require the above-described energy-consuming process and that can perform petroleum refining at normal temperature and normal pressure is currently awaited.

[0005] The content of nitrogen compounds in petroleum varies from 0.01 to 0.49% depending on the place of production, and the forms of organic nitrogen compounds present in petroleum are hardly removable organic nitrogen compounds,
For example, there are various types such as non-basic nitrogen compounds (mainly having a pyrrole ring and an indole ring) and basic nitrogen compounds (mainly having a pyridine ring and an acridine ring). In particular, aromatic nitrogen compounds such as carbazole (abbreviation CA), which are difficult to remove in the current process, can cause discoloration and coloring of petroleum products at high temperatures, and degrade the catalyst used in petroleum refining processes. This is a problem in the oil refining process. It is also desirable to establish a method that can be carried out under microaerobic conditions with a low risk of an accident such as an explosion also in these denitrification methods.

[0006]

SUMMARY OF THE INVENTION The present invention relates to the establishment of a method utilizing biotechnology as one of the means capable of refining petroleum at normal temperature and normal pressure, and more specifically, to a method for refining petroleum and coal. Microorganisms capable of specifically decomposing organic nitrogen compounds or converting them into compounds that can be easily removed are separated from the natural world, and establishment of denitrification means for petroleum and the like using such microorganisms has been established. Aim. In particular, it is desired to establish a denitrification means having a feature that one type of microorganism can decompose and remove different aromatic organic nitrogen compounds having a carbazole skeleton and a quinoline skeleton, which can be regarded as double shoulders of an aromatic organic nitrogen compound which is difficult to remove. ing. Furthermore, since the reaction target is an organic nitrogen compound that is difficult to remove in crude oil, it is not a hydrophilic reaction (aqueous reaction) inherent in microorganisms, but a two-phase system composed of a petroleum organic solvent / water system. The purpose is to establish a nitrogen reaction.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have separated microorganisms having the ability to decompose a specific organic nitrogen compound from the natural world, The present inventors have found that the problem can be solved by applying the method to the denitrification method, and have completed the present invention.

That is, the present invention is characterized in that a microorganism capable of decomposing an aromatic organic nitrogen compound is brought into contact with a substance containing the aromatic organic nitrogen compound to decompose the aromatic organic nitrogen compound. This is a denitrification method using a microorganism. Examples of the microorganism include microorganisms belonging to the genus Sphingomonas, and more specifically, CDH-7 of the genus Sphingomonas. These microorganisms are used in the form of cultured cells or quiescent cells. Examples of the aromatic organic nitrogen compounds include carbazole compounds and / or quinoline compounds.

The contact between the microorganism and a substance containing an aromatic organic nitrogen compound is carried out under aerobic or microaerobic conditions. The denitrification method can be carried out in a two-phase system consisting of an oil-based organic solvent / water system. Furthermore, the present invention decomposes the aromatic organic nitrogen compound by continuously contacting resting cells of a microorganism having the ability to decompose the aromatic organic nitrogen compound and a substance containing the aromatic organic nitrogen compound. It is a continuous denitrification method characterized by the above.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The denitrification method of the present invention is a biodenitrification method using a microorganism belonging to the genus Sphingomonas and capable of decomposing organic nitrogen compounds. Among the organic nitrogen compounds, carbazole, which is a typical chemical substance as a hard-to-removable organic nitrogen compound, is exemplified.The present inventor has the ability to assimilate and decompose the carbazole as a sole nitrogen source and sole carbon source. Bacteria were newly isolated from nature by the enrichment culture method under microaerobic conditions. Furthermore, the bacterium also assimilates quinoline, another typical compound having a skeleton as a hard-to-remove aromatic compound other than carbazole, as the sole nitrogen source and sole carbon source. In addition,
The microaerobic condition referred to in the present invention refers to an oxygen partial pressure condition below the explosion limit, which is usually 2% or less, preferably about 0.5%.

First, the screening of denitrifying bacteria used in the present invention will be described. Using soil, wastewater, crude oil sludge, etc. (approximately 350 points) collected from all over Japan, carbazole of the following formula, which is a typical chemical substance of organic nitrogen compounds that are difficult to remove by the current oil refining process (hereinafter,
Abbreviated as CA. )

[0012]

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The microorganisms that grew under oxygen-suppressing conditions close to the actual storage tank conditions were screened using only nitrogen as the sole nitrogen source. After performing enrichment culture at a temperature of 30 ° C. for 1 week, 2% of the culture solution was subcultured and further enrichment culture was performed. This operation was repeated four times or more, and the diluted solution of the culture solution that had been sufficiently accumulated was applied to a Rich agar medium containing CA. The colonies that appeared here were picked, and further cultured in an integrated manner in a liquid medium. This operation was repeated two or more times to separate those that grew.

In particular, at the time of the enrichment culture, a soil sample and CA were added to a test tube (50 ml) with a screw cap together with the screening medium 20, a Teflon tape was wrapped around the cap, and nitrogen was bubbled, followed by culturing at 30 ° C. for 7 days.
As shown in Table 1 below, a completely synthetic medium CD medium containing only CA as the nitrogen source was used as the screening medium containing only the organic nitrogen compound CA as the nitrogen source. In order to enhance the dispersing effect of CA, n-hexadecane was attached to the medium at a concentration of 0.5% (v / v).

[0015]

[Table 1] CD medium (pH 7.0) Carbazole 1.0 g or 0.5 g Na 2 HPO 4 1.6 g KH 2 PO 4 1.0 g MgSO 4 · 7H 2 O 0.5 g MgCl 2 · 6H 2 O 0.1 g CaCl 2 · 2H 2 O 0.025 g metal mixture Solution ^a) 2 ml Vitamin mixture ^b) 1 ml Add distilled water to make a total volume of 1000 ml. a) a metal mixture b) Vitamin mixture _{FeCl 2 · 4H 2 O 1.5 g} Ca- pantothenate _{400mg CoCl 2 · 6H 2 O 0.19} g Niacin _{400mg MnCl 2 · 4H 2 O 0.1} g pyridoxine hydrochloride 400 mg ZnCl ₂ 0.07 g inositol 200mg H ₃ BO ₃ 0.062 g p-aminobenzoate 200 mg Na ₂ MoO ₄ .2H ₂ O 0.036 g cyanocobalamin 50 mg NiCl ₂ .6H ₂ O 0.024 g Distilled water is added to make a total volume of 1000 ml. CuCl ₂ · 2H ₂ O 0.017 g distilled water 1000 ml

As a result of the above screening, several kinds of microorganisms capable of assimilating and using CA as the sole nitrogen source were obtained. Among several types of CA-degrading microorganisms obtained, CDH-7 strain showed the highest CA degrading ability. Table 2 shows the physiological and biochemical properties of this strain. As shown in Table 2, this strain was a gram-negative, catalase- and oxidase-positive bacillus, and from other various properties, this strain was identified as belonging to the genus Sphingomonas.

[0017]

Table 2 Physiological and biochemical properties of CDH-7 strain Cell morphology Bacillus Width μm 0.5-0.6 Length μm 1.5-5.0 Gram staining-Lysis with 3% KOH + Aminopeptidase + Spores-Oxidase + Catalase + Alcohol dehydrogenase - NO ₃ than NO ₂ generation - denitrification - urease - hydrolysed gelatin - esculin - starch - acid formation from glucose - utilizing glucose as carbon source - arabinose - xylose - D-ribose - rhamnose - caprylic Sainte - citric Acid trebulic acid-malic acid-mannitol- adonitol-

Furthermore, the nucleotide sequence of the 16S rDNA of the CDH-7 strain was determined, and the homology was examined. As a result, the homology was 96% with a bacterium belonging to the genus Sphingomonas. Tables 1 and 16
Based on the results of SrDNA, this strain was identified as a bacterium belonging to the genus Sphingomonas. The strain is Sphingomonas CDH
7 (Sphingomonas sp. CDH-7) as of February 19, 1997
It has been deposited with the National Institute of Bioscience and Biotechnology at the National Institute of Advanced Industrial Science and Technology, and its deposit number is FERM P-16089.

As the microorganism used in the present invention, any microorganism can be used as long as it has the ability to decompose aromatic organic nitrogen compounds, in addition to the above microorganisms. All of these microorganisms have organic solvent resistance. The cells of this strain are inoculated into a medium containing carbazole as a carbon source and nitrogen source at a temperature of 30 ° C. and a pH of 7.
It is obtained by culturing at 0 at aerobic for 24 to 48 hours.
The denitrification method of the present invention is characterized in that a denitrifying bacterium as described above is brought into contact with a substance containing an aromatic organic nitrogen compound to decompose and denitrify the substance.

Examples of the substance containing an organic nitrogen compound include crude oil, petroleum, and coal liquefied oil. These substances can be used as they are, but from the viewpoint of efficiently decomposing the organic nitrogen compound as a substrate, it is desirable to use, for example, a surfactant or to appropriately shake the reaction system. Thereby, the contact interface between the denitrifying bacteria and the organic nitrogen compound as a substrate can be increased, and the decomposition can be performed efficiently.

The amount of air in the decomposition reaction atmosphere is not particularly limited, but under aerobic conditions, the reaction is carried out in the presence of ordinary air. On the other hand, it is conceivable to set the reaction atmosphere to an anaerobic condition that is completely anoxic, but in actual application, setting up a facility with a completely anaerobic condition requires a large amount of funds, In addition, since the operating cost is high, it cannot be said to be a practical method. For these reasons, it is preferable to carry out the reaction under microaerobic conditions in the presence of slight oxygen, or under facultative anaerobic conditions. Also, considering the state of the storage tank at the time of the reaction,
It is preferred to carry out the reaction under the above microaerobic conditions.

The specific oxygen content under such microaerobic conditions is 2% or less below the explosion limit, preferably 0.5% (v / v).
It is preferred to be on the order of magnitude. The temperature at the time of the decomposition reaction is not particularly limited as long as it is a temperature at which the denitrifying bacteria can act, but generally 10 to 45 ° C, and preferably around 30 ° C.

As a component of the decomposition reaction system, in addition to a substance containing a denitrifying bacterium and an organic nitrogen compound, it can react if there is appropriate water, but for the purpose of improving the reactivity of the denitrifying bacterium. It is preferable to appropriately add an inorganic substance or a nutrient source such as a general easily decomposable organic nitrogen source or an inorganic salt to the reaction system.

The reaction can be performed by a column method or a batch method. When performing the reaction by the column method, it is necessary to immobilize the denitrifying bacteria on an appropriate reaction column by an appropriate method.

After the biodenitrification reaction as described above, a known separation / purification process is usually applied. For example, the petroleum after denitrification can be directly applied to a petroleum refining device (topper) generally used at present. However,
In the present invention, it is not indispensable that the separation and purification steps be performed after the denitrification reaction.

Since the target reactant is a hardly removable aromatic compound in crude oil, the concentration of crude oil or the like as a reaction substrate is extremely low in a hydrophilic reaction (aqueous reaction) which microorganisms are originally good at in terms of cost. Thinking that it is impossible in
Another important issue in the present invention is how to increase the concentration of the reaction target such as crude oil. Under such circumstances, a petroleum organic solvent /
By enabling the CA decomposition reaction in a two-phase system consisting of an aqueous system, this reaction has become possible with petroleum fractions (products) such as crude oil, kerosene, and light oil. In addition, since the cultured resting cells can be used repeatedly for the reaction, they have great significance in terms of cost, and the continuation of the reaction using the resting cells has been made possible.

[0027]

The present invention will be described more specifically with reference to the following examples. However, the technical scope of the present invention is not limited by these examples.

Example 1 CA Decomposition Test Using a medium for denitrifying bacteria containing carbazole (CA), a hardly removable organic nitrogen compound, as a carbon source and a nitrogen source, under aerobic and microaerobic conditions. Denitrifying bacteria (Sphingomonas spp.)
sp. CDH-7) to conduct a CA decomposition test. The composition of the medium for denitrifying bacteria is a CD medium containing 500 / CA.

Specifically, for the culture of the denitrifying bacteria (Sphingomonas sp. Strain CDH-7), the suspension is put in a vial (100 ml) together with 30 ml of the above-mentioned medium for denitrifying bacteria, and aerobically and under nitrogen. The cells were sealed after bubbling, and cultured by shaking at 30 ° C. under aerobic and microaerobic conditions. In addition, shaking culture was employed to enhance the contact between the substrate and the denitrifying bacteria because CA is a solid substance.

CA and metabolic degradation product anthranilic acid (AN)
Quantification was performed by acidifying the culture solution with hydrochloric acid, extracting the mixture with ethyl acetate, and analyzing the supernatant (ethyl acetate solution containing CA) by high performance liquid chromatography (abbreviated HPLC). In addition, dibenzofuran was used as an internal standard for the analysis. NH4 + was measured using an ammonia measurement kit manufactured by Wako Pure Chemical. The growth of the CDH-7 strain was measured at a concentration (OD) at 660 nm. As a representative example of the carbazole degradation by this strain, the time course of CA degradation under aerobic conditions is shown in FIG.

From the above results, in the denitrifying bacterium Sphingomonas sp. Strain CDH-7, CA decreased sharply after 20 hours of culture under microaerobic conditions, and the growth and growth of the CDH-7 strain were thereby accompanied. Recognized, and as CA decreased, AN
Temporarily accumulated but decreased thereafter, and trace amounts of NH ₄ ⁺ were present after 40 hours of culture. This confirmed that CA was degraded and consumed with high efficiency by this strain. Under microaerobic conditions, decomposition of carbazole was observed, although decomposition activity was reduced.

The metabolic degradation product of CA by CDH-7 strain was confirmed by analyzing the culture medium extract of CD medium containing only the above CA of CDH-7 strain as a nitrogen source by HPLC and gas mass spectrometer (abbreviated GC-MS). did. As a result, the presence of anthranilic acid (AN) was confirmed. From this, it was confirmed that CA was finally completely decomposed to ammonium ions via the AN by the CDH-7 strain. The decomposition reaction format of CA is shown below.

[0033]

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[Example 2] Decomposition test of quinoline Next, the decomposition process of quinoline which shows one typical skeleton of the hardly removable aromatic compound other than carbazole will be described. Example 1
Is the same as Example 1 except that carbazole in was replaced with quinoline. As a result, by the CDH-7 strain, quinoline was reduced by 40% in 20 hours of culture and completely degraded in the same manner as carbazole in 72 hours of culture. The quinoline was measured by HPLC using dibenzofuran as an internal standard in the same manner as carbazole.

Example 3 Decomposition of CA by Resting Bacterial Cell Reaction When the process of the present invention is aimed at, a continuous reaction using resting cells is considered as one process. From this viewpoint, first, CA degradation by a resting bacterial cell reaction using the CDH-7 strain was examined.

(Preparation method of resting cells)
100 ml of CD medium containing 00 mg / l CA, 0.5 ml of n-hexadecane
In addition, the CDH-7 strain was inoculated with one platinum loop using platinum wire enzyme, and then cultured at 30 ° C. for 33 to 35 hours. CDH by centrifugation
After collecting 7 strains, 50 mM potassium phosphate buffer (pH 7.0)
Was washed twice. CA remaining in the suspension suspended in the same buffer was removed by passing through a glass filter (17G2). As a result, CDH-
Seven suspensions of resting bacterial cells were prepared.

(Decomposition of CA by Resting Cells) The concentration of resting cells used in the reaction was 2.2 mg / ml in terms of dry cells, and 10 ml of this suspension of resting cells and 50 ml of n-hexadecane 1 were used. Add to vial. Initial CA concentration of 100mg / l or 500mg
/ l, 100μl of ethanol solution with CA dissolved
And a resting cell reaction is performed at 30 ° C. for a certain period of time. 6N-H
After stopping the reaction by adding 200 μl of Cl, CA, AN, and NH ₄ ⁺ were quantified in the same manner as in Example 1.

FIG. 2 (A and B) show the results. Figure 2-
A: CA initial concentration is 100 mg / l; Fig. 2-B: CA initial concentration is 500 mg / l
This is an example. As shown in FIG. 2-A, when the initial concentration of CA was 100 mg / l, CA was completely decomposed in 30 minutes after the reaction, and there was no accumulation of the intermediate metabolite AN in the reaction solution, and a trace amount of NH. ₄ ⁺ has not only are present. Even when the initial concentration of CA was 500 mg / l, the quiescent bacterial cell reaction proceeded efficiently, and CA was completely decomposed in 4 hours of the reaction. Temporarily put AN in the reaction solution
, But soon decrease,
The presence of NH ₄ ⁺ was observed. From the above results, it was found that CA was completely degraded with high efficiency by the quiescent bacterial reaction of CDH-7 strain.

Example 4 Continuous Decomposition of CA by Resting Cell Reaction In a reaction using a microorganism, how many times the microorganism can be regenerated has a large weight in terms of cost. For the purpose of cost reduction, continuous degradation of CA was examined to determine how many times the once prepared resting cells could be reused. The suspended cell suspension used was prepared in the same manner as in Example 3 (cell concentration: 2.2 mg / ml), the concentration of CA added was 100 mg / l, and the next 100 mg / l immediately after CA was completely degraded. Was added successively to perform a resting cell reaction. The results are shown in FIG.
From this figure, it can be seen that CA was completely decomposed in the ninth consecutive reaction, and that continuous decomposition of CA was possible for 42 hours under these conditions. Although the tenth CA decomposition reaction for 48 hours was not complete, 950 mg / l of total CA was decomposed under these conditions. As shown above,
By examining appropriate conditions, it was found that continuous complete degradation of sequentially added CA using resting cells of CDH-7 was possible.

Example 5 CA Decomposition in a Two-Phase System Consisting of a Petroleum Organic Solvent / Water System Originally, microorganisms are hydrophilic organisms and exhibit their activity in aqueous systems. On the other hand, the target object of the present invention is a hard-to-removable aromatic organic nitrogen compound in crude oil or the like, which is contradictory when its reaction system is considered. As a result of intensive studies to overcome such contradicting points, Sphingomonas sp. CDH-7 is a very rare organic solvent-resistant aromatic organic nitrogen compound that has the characteristics of showing resistance to petroleum organic solvents. They discovered for the first time that they were microorganisms, and opened the way to the process of the present invention.

(CA Decomposition Reaction in Two-Phase System of Various Petroleum Organic Solvents / Water System) The bacterial cell concentration of the CDH-7 strain used in the reaction was set to 4.4 mg / ml, twice that of Example 3. 20% (v / v) of petroleum organic solvents (isooctane, n-hexane, cyclohexane, ρ-xylene, toluene) in aqueous solution, and 20, 50, 100% kerosene (kerosene) as model oil
(V / v) Overlaid, the initial CA concentration was set to 100 /, and a resting cell reaction was performed for 1 hour. FIG. 4 shows the results. As shown in this figure,
When isooctane, n-hexane and cyclohexane were layered, CA was completely decomposed. Also, in petroleum organic solvents having high cytotoxicity such as ρ-xylene and toluene, the decomposition rate was slightly reduced, but CA decomposition was confirmed. In addition, CA was completely decomposed even if kerosene (kerosene) was layered at 20% or 50% (v / v). At 100% (v / v), the CA decomposition rate decreased. From the above results, it was found that this strain exhibited high resistance to petroleum organic solvents and was able to degrade CA in a two-phase system.

(CA Decomposition by Changing Cell Concentration in a Two-Phase System of Petroleum Organic Solvent / Water System) Toluene is 20% (v / v) as an example of a petroleum organic solvent and a highly cytotoxic organic solvent.
v) Layering was performed, and the decomposition of CA was examined by changing the cell concentration. FIG. 5 shows the results. When the bacterial mass was increased, the CA decomposition rate was increased, and CA decomposition was confirmed even in the presence of toluene.

Example 6 Cell Life of Sphingomonas CDH-7 Strain in the Presence of an Organic Solvent As shown in Example 4, this microorganism is a robust microorganism that can be repeated many times, Degradation reaction was shown to be possible, but considering the actual process, it is also extremely important how long the bacterial cell life and the CA decomposition activity are maintained in the presence of an organic solvent. From this viewpoint, the cell concentration of the CDH-7 strain was increased to 2.2 as in Example 3.
mg / ml, add 10 equivalents of n-hexadecane as an example of an organic solvent to the cell suspension 10, and add 3 equivalents at 30 ° C.
After shaking (7 days), 100 mg / l of CA was added and a resting cell reaction was performed for 1 hour, and the life of the cells in the presence of an organic solvent (remaining CA decomposition activity) was examined. Table 3 shows the results. As shown in Table 3, it was confirmed that the strain CDH-7 maintained the CA-decomposing activity even after being contacted with an equal amount of n-hexadecane for 7 days.

[0044]

[Table 3]

[0045]

According to the present invention, it is possible to remove hard-to-removable aromatic organic nitrogen compounds from petroleum and coal at normal temperature and normal pressure. Therefore, the present invention can be used as a part of a petroleum refining process, and petroleum and coal can be refined at normal temperature and normal pressure.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a graph showing the time course of CA degradation by Sphingomonas strain CDH-7.

FIG. 2. C by resting cells of Sphingomonas sp. Strain CDH-7
The figure which shows the time-dependent change of A decomposition.

FIG. 3 is a diagram showing continuous degradation by quiescent cells of Sphingomonas sp. Strain CDH-7.

FIG. 4 is a diagram showing a CA decomposition reaction in a two-phase system of various petroleum organic solvents / water systems using Sphingomonas sp. Strain CDH-7.

FIG. 5 shows changes in bacterial cell concentration in a two-phase system composed of petroleum organic solvent / water using Sphingomonas sp. Strain CDH-7.
The figure which shows the change of CA decomposition.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shoji Usami 384-9, Mizuno, Sayama-shi, Saitama (72) Kotaro Kirimura 2-10-3, Kakinokizaka, Meguro-ku, Tokyo (72) Inventor Kenji Tsuji Tokyo 6-16-16 Shakujiicho, Nerima-ku, Tokyo Corporate Lakeside 201

Claims (10)

[Claims] 1. A method according to claim 1, wherein a microorganism capable of decomposing the aromatic organic nitrogen compound is brought into contact with a substance containing the aromatic organic nitrogen compound to decompose the aromatic organic nitrogen compound. Nitrogen method. 2. The denitrification method according to claim 1, wherein the microorganism having the ability to degrade an aromatic organic nitrogen compound is a microorganism belonging to the genus Sphingomonas. 3. The method according to claim 2, wherein the microorganism belonging to the genus Sphingomonas is Sphingomonas genus CDH-7. 4. The denitrification method according to claim 1, wherein the aromatic organic nitrogen compound is a carbazole compound and / or a quinoline compound. 5. The denitrification method according to claim 1, wherein the microorganism is contacted with a substance containing an aromatic organic nitrogen compound under aerobic or microaerobic conditions. . 6. The method according to claim 1, wherein the microorganism is a cultured cell or a quiescent cell. 7. The method according to claim 1, wherein the method is carried out in a two-phase system consisting of a petroleum organic solvent / water system. 8. An aromatic organic nitrogen compound is decomposed by continuously contacting resting cells of a microorganism having the ability to decompose the aromatic organic nitrogen compound with a substance containing the aromatic organic nitrogen compound. A continuous denitrification method, characterized in that: 9. The microorganism belonging to the genus Sphingomonas is Sphingomonas bacterium CDH-7,
9. The continuous denitrification method according to claim 8. 10. The continuous denitrification method according to claim 9, wherein the aromatic organic nitrogen compound is a carbazole compound and / or a quinoline compound.