JP2011244797A - Bacterium involved in suppression of increase of malaria parasite, malaria therapeutic agent, and production method of agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bacterium with which a suppressive substance suppressing an increase of a malaria parasite at an low cost and easily without the need for such a treatment by an expensive enzyme that a thick cell wall like Acromopeptidase is specifically decomposed.SOLUTION: Provided is a bacterium belonging to either of the genus Ochrobactrum and the genus Serratia, which produces a suppressive substance suppressing an increase of malaria parasites. A malaria therapeutic agent having, as effective ingredient, a cultured material obtained by cultivating the bacterium belonging to either of the genus Ochrobactrum and the genus Serratia is also provided.

Description

  The present invention relates to a microorganism that produces a substance useful for treatment of infectious diseases caused by malaria parasites, a malaria therapeutic agent using the substance, and a production method thereof.

  It is no exaggeration to say that malaria is the most important infectious disease, with more than 400 million people infecting each year, of which millions of people are killed. Until now, this threat has been mainly in the subtropics and the tropics, but reports of infections by travelers and imported infectious diseases accompanying the expansion of global economic activity are increasing rapidly in Japan. Also, in recent years, resistant species against conventional drugs have spread, and there is a concern over the expansion of the infected area due to global warming, so the development of a new antimalarial agent is urgently needed.

  Malaria parasites that infest humans include Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, and Plasmodium varieties of Plasmodium plasmodium. being classified. Among these, the most troublesome is P. falciparum, which accounts for 80% of those infected with malaria, and in severe cases it becomes cerebral malaria and is fatal. As the existing antimalarial agents for these malaria parasites, chemical synthetic drugs such as chloroquine and funcidal (combination of pyrimesamine and sulfadoxine), and artemisinin, which is an active ingredient of herbal medicine blue glaze, are used. It was.

  In the mammalian body, the malaria parasite invades the erythrocyte and repeats division and proliferation. Malaria parasites use hemoglobin in erythrocytes as an amino acid source, but free heme remaining in the protozoa is harmful to the protozoa because of its strong oxidizing power. Therefore, the malaria parasite is equipped with a system for polymerizing free heme, that is, a system for detoxifying and excreting heme. Currently used malaria treatment agents such as quinoline drugs and artemisinin developed from quinine inhibit the heme polymerization, and it is thought that malaria parasites have shown their medicinal effects by preventing the detoxification of heme. The mechanism of action of chloroquine and fancidar is considered to be that quinoline inhibits the mechanism of detoxification of heme during the metabolism of hemoglobin in the erythrocyte parasitic stage of the genus Plasmodium by complex formation with divalent iron. (See, for example, Non-Patent Document 1). From such a background, inhibition of heme polymerization is considered to be effective for the treatment and prevention of malaria.

  Patent Document 1 reports the development of a compound having a quinoline ring with respect to the development of a therapeutic agent for malaria by inhibiting heme polymerization. The compound in this case is obtained by chemical synthesis. However, chemical synthesis methods generally require the use of toxic reagents such as benzene, strong acids, strong alkalis, high temperature and pressure conditions, and multistage reactions. For example, in the case of a quinoline compound that is the basic skeleton of chloroquine, depending on the quinoline compound, synthesis itself is difficult, and it is difficult to obtain a compound having a desired structure. In addition, plant extracts typified by artemisinin require labor when purifying a target substance from a water-soluble compound such as a polysaccharide. Therefore, it is extremely advantageous from the viewpoint of production if the target substance can be produced in one step by microorganism culture from an inexpensive raw material such as sugar instead of a chemical synthesis method.

  Patent Document 2 and Non-Patent Document 2 describe polyether antibiotics by Streptomyces genus actinomycetes for microbial culture extracts having antimalarial activity.

  Patent Document 3 describes borrelidin caused by actinomycetes with respect to a microorganism culture extract having antimalarial activity.

However, actinomycetes belong to Gram-positive bacteria, the cell walls are thick, and 80% of them are peptidoglycans, so the cell walls are strong. Therefore, in order to disrupt the cell wall of actinomycetes, treatment with an expensive enzyme that specifically decomposes a thick cell wall such as achromopeptidase is required. It will be expensive. Furthermore, since the process which removes the used achromopeptidase is also needed, it is complicated compared with Gram-negative bacteria to collect a product.
Among the gram-positive bacteria, particularly, filamentous filamentous cells and actinomycetes that form mycelia are known to have a function of producing secondary metabolites having various physiological activities. However, in spite of the necessity of agitation for the purpose of supplying oxygen for mass production, actinomycetes often show a filamentous form, which is caused by cell rupture due to physical shearing associated with agitation. In order to carry out highly reproducible production, it is necessary to appropriately manage agitation.

JP 2008-1630 A JP 2003-335667 A JP 2004-269440 A

Nguyen Tien Huy, 7 others, “Clotrimazole binds to heme and promotes heme-dependent hemolysis: the proposed anti-malarial mechanism of clotrimazole (Clotrimazole binds to hemens hemes) -Dependent hemogenesis: the journal of biological chemistry (USA), the Journal of Biological Chemistry, United States of Biochemistry, United States, Biomolecules, Biomolecules, Biochemistry, and Biochemistry. , 2002 Month, 277 Vol., No. 6, p. 4152-4158 Jacques Advelande, 1 other, “Carboxylic acid ionophore in malaria chemotherapy: effects of momensin and nigericin on Plasmodium falciparum in vitro and Plasmodium vinkei petelli in vivo chemotherapy: the effects of monensin and nigerin on Plasmodium falciparum in vitro and Plasmodium vinckei petteri in viv (E), v e. ), 1996, Vol. 59, No. 20, p. 309-315

  The present invention has been made in view of the above problems, and its purpose is low-cost without treatment with an expensive enzyme that specifically degrades a thick cell wall such as achromopeptidase. It is an object of the present invention to provide a bacterium that can easily recover an inhibitory substance that suppresses the growth of Plasmodium. It is another object of the present invention to provide a bacterium capable of producing the inhibitory substance with high reproducibility without appropriate management of stirring. Furthermore, malaria-infected areas are developing countries belonging to the tropics and subtropics such as Asia, Africa, and Central and South America, where the medical system and economic infrastructure are not enriched. Malaria treatment agents that can be produced easily at low cost are desired. In view of the above, another object of the present invention is to provide a malaria therapeutic agent using the inhibitor and a low-cost and simple method for producing a malaria therapeutic agent.

  In order to achieve at least a part of the above object, the bacterium according to the present invention has taken the following measures.

  The gist of the present invention is that the bacterium of the present invention belongs to either the genus Ochrobactrum or Serratia, which produces an inhibitory substance that suppresses the growth of Plasmodium.

  Moreover, in the bacterium of the present invention, the inhibitory substance may be characterized by suppressing the growth of the malaria parasite by inhibiting the heme polymerization of the malaria parasite.

  Moreover, the bacterium of the present invention may be characterized in that the bacterium belonging to the genus Oklobactrum is the oclobactrum FERM P-21915 strain.

  Moreover, in the bacterium of the present invention, the bacterium belonging to the genus Serratia may be the Serratia FERM P-21914 strain.

  The gist of the therapeutic agent for malaria of the present invention is that a culture obtained by culturing a bacterium belonging to the genus Oklobactrum or Serratia is an active ingredient.

  Moreover, the malaria therapeutic agent of this invention can also suppress the proliferation of this malaria parasite by inhibiting the heme polymerization of the malaria parasite.

  Moreover, the therapeutic agent for malaria of the present invention may be characterized in that the supernatant fraction of the culture is used as an active ingredient.

  The malaria therapeutic agent of the present invention may be characterized in that the bacterium belonging to the genus Oclobactrum is Oclobactrum FERM P-21915 strain.

  In addition, in the agent for treating malaria of the present invention, the bacterium belonging to the genus Serratia is Serratia FERM P-21914 strain.

  The summary of the method for producing a malaria therapeutic agent of the present invention is to perform at least a step of collecting a culture obtained by culturing a bacterium belonging to either the genus Ochrobactrum or Serratia.

  Further, in the method for producing a therapeutic agent for malaria of the present invention, the bacterium belonging to the genus Oclobactrum can be characterized by Oclobactrum FERM P-21915 strain.

  Further, in the method for producing a therapeutic agent for malaria according to the present invention, the bacterium belonging to the genus Serratia is Serratia FERM P-21914 strain.

  The method for producing a malaria therapeutic agent of the present invention comprises at least a step of extracting a supernatant fraction from a culture obtained by culturing a bacterium belonging to either the genus Ochrobactrum or Serratia, and collecting the supernatant fraction. To do.

  Further, in the method for producing a therapeutic agent for malaria of the present invention, the bacterium belonging to the genus Oclobactrum can be characterized by Oclobactrum FERM P-21915 strain.

  Further, in the method for producing a therapeutic agent for malaria according to the present invention, the bacterium belonging to the genus Serratia is Serratia FERM P-21914 strain.

Since the bacterium of the present invention is a gram-negative bacterium, it suppresses the growth of malaria parasites easily and inexpensively without treatment with an expensive enzyme that specifically degrades a thick cell wall such as achromopeptidase. The inhibitory substance can be recovered. In addition, since the bacterium of the present invention is a gram-negative bacterium, the inhibitory substance can be produced with high reproducibility without appropriately managing the stirring required for actinomycetes.
On the other hand, since the anti-malarial agent of the present invention is produced using a gram-negative bacterium, the treatment with an expensive enzyme that specifically decomposes a thick cell wall such as achromopeptidase can be performed at low cost and easily. Can be produced. Moreover, since the malaria therapeutic agent of the present invention is produced using a gram-negative bacterium, it can be produced with high reproducibility without appropriate management of stirring as required by actinomycetes.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, the present invention will be described in detail. The bacterium used in the present invention belongs to the genus Oklobactrum or Serratia, but is not particularly limited as long as it is a microorganism that produces a suppressor that suppresses heme polymerization and malaria division and proliferation. For example, Okobactrum sp. Strain 34-29 and Serratia sp. Strain 44-1 are preferably used, but any strain can be used as long as it has substantially the same mycological properties. The Ochrobactrum genus 34-29 and Serratia genus 44-1 were discovered by screening from various types of soils collected by the present inventors from Ishigaki City and Miyakojima City, Okinawa Prefecture.

  From a comparison of 16S rRNA sequences, strain 34-29 is 99.7% identical to the 16S rRNA sequence of the standard strain of Oklobactrum anthropi (deposited as ATCC 49188 in the American Type Culture Collection American Type Culture Collection), and strain 44-1 is Serratia. Since it matched 99.7% with the 16S rRNA sequence of a standard strain of Marcesence (deposited as DSM 30121 in the German Microorganism Depositary, German microorganism deposit center), it was identified as Ocrobactrum genus and Serratia genus, respectively. These strains exhibit the mycological properties shown in Table 1. These strains were deposited with the National Institute of Advanced Industrial Science and Technology as of February 15, 2010, and accession numbers FERM P-21915 and FERM P-21914 have been obtained, respectively.

  So far, there has been no report regarding the registered strains of the genus Oklobactrum or Serratia having the ability to produce inhibitors that suppress the growth of Plasmodium, whereas the 34-29 and 44-1 strains are described later Have such ability. Therefore, it was found that the 34-29 strain was a new strain belonging to the genus Okrobactrum, and the 44-1 strain was a new strain belonging to the genus Serratia.

  The culture of the bacterium used in the present invention is performed according to a normal culture method of bacteria. The culture form may be either solid culture or liquid culture, but liquid culture is preferred. Commonly used nutrient sources for the medium are widely used. Any carbon compound may be used as the carbon source. For example, glucose, sucrose, lactose, succinic acid, citric acid, acetic acid and the like are used. The nitrogen source may be any available nitrogen compound. For example, organic nutrients such as peptone, polypeptone, meat extract, soybean meal, and casein hydrolyzate are used. In addition, phosphate, carbonate, magnesium, calcium, potassium, sodium, iron, manganese, zinc, molybdenum, tungsten, copper, vitamins, and the like are used as necessary. Culturing is performed at a temperature and pH at which the bacteria can grow, and is preferably performed under the optimal culture conditions for the bacteria to be used. In general, the pH of the medium is adjusted to an appropriate pH, for example, pH 6-8, and is preferably cultured under normal bacterial culture conditions at an appropriate temperature, for example, 25-35 ° C, preferably 30 ° C, under shaking or aeration conditions. It is done spiritually. Production of an inhibitory substance that suppresses the growth of the Plasmodium parasite according to the present invention can be performed by culturing the above-mentioned bacteria under the above-mentioned conditions in the above-mentioned medium.

  Hereinafter, the present invention will be specifically described with practical examples, but the technical scope of the present invention is not limited to these practical examples.

Example 1: Preparation of culture extract 5 mL of medium (adjusted to soluble starch, polypeptone, meat extract 10 g each, deionized water 1 L, pH 7.2) in a test tube having an inner diameter of 18 mm was sealed with a silicone stopper, 121 ° C, An autoclave treatment was performed in 20 minutes to obtain a PC-1 liquid medium. Thereafter, the PC-1 liquid medium was inoculated with Ocrobactrum sp. 34-29 or Serratia sp. 44-1 stored at 4 ° C. in PC-1 agar medium (PC-1 medium supplemented with 15 g of agar powder). The aerobic culture was performed using a Taitec BR-40LF type under conditions of 150 rpm at 30 ° C. for 3 days to obtain a PC-1 culture solution. Further, 20 mL of medium (soluble starch 2.5 g, soy bean meal 1.5 g, dry yeast 0.2 g, calcium carbonate 0.4 g, deionized water 1 L, pH 7) is prepared in a 100 mL baffle Erlenmeyer flask sealed with a silico stopper. Thereafter, autoclaving was similarly performed to obtain K medium. Further, 1 mL of the PC-1 culture solution of Okobactrum genus 34-29 or Serratia genus 44-1 obtained as described above was inoculated into K medium and cultured aerobically at 30 ° C. for 7 days. An equal amount of acetone was added to the obtained culture to obtain a culture extract. Here, acetone is added to the culture to facilitate the dissolution of the culture, which is a metabolic product of microorganisms, but methanol or dimethyl sulfoxide may be added as long as it can dissolve the culture. May be.

Example 2: Inhibitory activity test of heme polymerization using Tween 20 The inhibitory activity test of heme polymerization using the culture extract obtained in Example 1 was conducted according to the method reported by Huy et al. (Nguyen Thien・ Huy (Nguyen Tien Huy), 6 others, “Simple colorimetric inhibition of hematology and hydration of the anti-malarial substance, using a colorimetric method for high-throughput screening of anti-malarial substances. ”, (USA), Antimicrobials Agents and Chemotherapy rapy), the United States Society for Microbiology (American Society for Microbilogy), 1 January 2007, Vol. 51, No. 1, p.350-353). In this method, heme is mixed with hemin, which has a single chloride ion in heme, by mixing TWEEN 20 (polyoxyethylene (20) sorbitan monolaurate), which is a nonionic surfactant, as a polymerization initiator. Polymerize. A filter prepared by dissolving 20 mg of hemin (manufactured by Fluka) in 1.4 mL of dimethyl sulfoxide (manufactured by Nacalai) and 48 mg of Tween 20 (manufactured by Sigma) in 1 L of deionized water, Insoluble matter was removed with a 3 μm hole diameter) to obtain a hemin solution and a Tween 20 solution. Next, 5 mL of 1 M acetate buffer (pH 4.8) was mixed with the above hemin solution and 0.1 N aqueous sulfuric acid solution to a final concentration of 50 μM and 20 mM, respectively. A Tween 20 (+) sample to which a Tween 20 solution was added to a final concentration of 12 mg / L and a Tween 20 (-) sample to which deionized water was added instead of the Tween 20 solution were prepared. Samples added with Ochrobactrum spp. 34-29 culture extract to each of these Tween20 (+) samples and Tween20 (-) samples, samples added with culture extract of Serratia spp. 44-1 strain, samples added with chloroquine A total of 8 samples were prepared, in which nothing was added. Here, the Ochrobactrum genus 34-29 strain or Serratia genus 44-1 strain culture extract was added to the Tween 20 (+) sample or the Tween 20 (-) sample in an amount of a quarter of the final reaction solution. On the other hand, as a chloroquine sample that is a typical antimalarial agent, 51.586 mg of chloroquine diphosphate (manufactured by Wako Pure Chemical Industries, Ltd.) dissolved in 1 mL of deionized water is used so that the final concentration of chloroquine is 1 mM. Added to Tween 20 (+) or Tween 20 (-) samples. A total of 8 samples were incubated at 37 ° C. for 250 minutes. Thereby, heme polymerization reaction occurs in the sample containing Tween20. The polymerization of heme was determined by subtracting the value of absorbance at 615 nm (turbidity due to hemozoin formation, which is a heme polymerized product) from the value of absorbance at 415 nm (heme absorption wavelength) (415-615 nm value). . That is, when Tween 20 is added, heme is polymerized, the absorbance at a wavelength of 415 nm is decreased, and the absorbance at a wavelength of 615 nm is increased, so that the value of 415 to 615 nm is decreased. The heme polymerization inhibitory activity (A ratio) of the additive can be determined by dividing the 415-615 nm value of the sample containing Tween 20 by the 415-615 nm value of the sample not containing Tween 20. It shows that inhibitory activity is so high that A ratio is high. The experimental results are shown in Table 2. Since the A ratio of the sample to which chloroquine was added was higher than the A ratio of the sample without the additive, the validity of this evaluation method could be verified. Further, even when the Ochrobactrum sp. 34-29 or Serratia sp. 44-1 culture extract was added, the A ratio was remarkably high, and both culture extracts showed high heme polymerization inhibitory activity. Therefore, it was found that cultures obtained by culturing Ochrobactrum sp. Strain 34-29 and Serratia sp. Strain 44-1 inhibit heme polymerization. As a result, it was found that Oklobactrum sp. 34-29 and Serratia sp. 44-1 produce substances that inhibit heme polymerization.

  Further, the culture obtained by culturing in the same manner as in Example 1 was centrifuged under conditions of 3,000 rpm, 4 ° C., and 5 minutes, and the supernatant and the bacterial cell fraction were collected. The same amount as the culture broth was added to obtain a supernatant fraction extract and a cell fraction extract, respectively. Here, acetone is added to the culture to facilitate the dissolution of the culture, which is a metabolic product of microorganisms, but methanol or dimethyl sulfoxide may be added as long as it can dissolve the culture. May be. Using these fraction extracts, the A ratio was compared by the same evaluation method as described above. The results are shown in Table 3. As for the Ochrobactrum genus 34-29, when the cell fraction extract was added, the A ratio was the same as when no additive was added, whereas when the supernatant fraction extract was added, the A ratio was high. This indicates that the supernatant fraction extract has an inhibitory effect on heme polymerization activity. On the other hand, Serratia sp. 44-1 strain showed an inhibitory activity on the heme polymerization reaction in both the supernatant and the cell fraction extract, but the ratio A when the supernatant fraction extract was added was the cell fraction. Since it was slightly higher than the A ratio when the extract was added, it was found that the supernatant fraction extract had a slightly stronger inhibitory activity on the heme polymerization reaction than the cell fraction extract. Therefore, it was found that the supernatant fraction of the cultures obtained by culturing Ochrobactrum sp. Strain 34-29 and Serratia sp. Strain 44-1 inhibited heme polymerization.

Practical example 3: Inhibitory activity test of heme polymerization by crude malaria parasite extract This test was carried out according to the method reported by Arawal et al. (Rashmi Agrawal), five others, "cyproheptadine has Haem polymerase as a novel target of antigenic activity as a new target of anti-malarial activity "(UK), Biochemical Pharmecology (Biochemical Pharmecology 2) November, Vol. 64, No. 9, pp. 1399-1406). In this method, infected erythrocytes collected from malaria-infected mice are destroyed to recover malaria parasites, and a crude extract of the parasites is mixed to polymerize heme. In other words, this method is a method in which the heme polymerization system provided in the malaria parasite is reproduced in vitro. 3 mL blood was collected from the heart of 3 mouse malaria infected mice using a syringe. The collected blood dissolved in 9 mL of an aqueous solution containing 136 mM glucose, 85 mM trisodium citrate and 38 mM citric acid was centrifuged at room temperature and 1,500 rpm for 10 minutes, and the precipitate was used as the red blood cell fraction. The erythrocyte fraction was washed with 22 mM phosphate buffer (pH 7.4) and then suspended in about 2.8 mL of 22 mM phosphate buffer (pH 7.4) in which 9 g / L glucose was dissolved. 1 mL of the suspension was immersed in liquid nitrogen for 5 minutes, frozen, and thawed at room temperature to destroy erythrocytes and malaria parasites in the suspension. Centrifugal malaria parasite was centrifuged at 13,000 rpm for 20 minutes at 4 ° C, and the resulting precipitate suspended in 0.5 mL of 100 mM acetate buffer (pH 5.0) was roughly extracted. It was a thing. The polymerization reaction of heme consists of 1 mM hemin 100 μL, 1 M acetate buffer (pH 5.0) 100 μL, malaria protozoa crude extract 50 μL and Ochrobactrum 34-29 or Serratia 44-1 strain culture extract 50 μL, sterile deionized The reaction was performed by adding 700 μL of water and shaking at 37 ° C. for 4 hours. Moreover, what added 50 microliters of 20 mM chloroquine (final concentration 1 mM) instead of the culture extract of each strain was made into the positive control of heme polymerization inhibition, and the thing which added 50 microliters of deionized water was made into the negative control. After completion of the reaction, the precipitate obtained by centrifugation at 13,000 rpm for 5 minutes at room temperature was once in 100 mM Tris buffer (pH 7.4) containing 2.5 mass% SDS (sodium dodecyl sulfate). A precipitate obtained after washing twice with 100 mM Tris buffer (pH 7.4) and once with 100 mM bicarbonate buffer (pH 9.0), followed by centrifugation at 13,000 rpm for 5 minutes at room temperature The product was used as a polymerized heme fraction. The polymerized heme fraction was dissolved in 50 μL of 2N NaOH and 950 μL of a 2.5 mass% SDS aqueous solution to form free heme, and the amount of the polymerized heme was measured by measuring the absorbance at a wavelength of 400 nm. For the amount of polymerized heme, the experiment under the same conditions was performed three times, and the average value and the standard deviation of the measured values were calculated. The results are shown in Table 4. From the results of Table 4, the amount of polymerized heme measured when the Ochrobactrum sp. Strain 34-29 or Serratia sp. 44-1 strain culture extract was added was extremely low compared to the case without additives. It is clear that heme polymerization activity was inhibited by the culture extract. The effect was similar to that of a typical synthetic antimalarial drug chloroquine. Therefore, it was found that cultures obtained by culturing Ochrobactrum sp. 34-29 and Serratia sp. 44-1 inhibit heme polymerization of malaria parasites. Thus, it was found that Oklobactrum sp. 34-29 and Serratia sp. 44-1 produce substances that inhibit heme polymerization of Plasmodium.

Practical example 4: Growth / proliferation inhibition test of lethal malaria parasite in mouse Blood containing mouse lethal mouse malaria (P. berghei) is mixed with 22 mM phosphate buffer (pH 7.4) containing 15 uL heparin (manufactured by Nipro Pharma). And adjusted to 10 ⁶ -infected erythrocytes / 100 uL to obtain an infected blood sample. A male wild-type mouse of 12 weeks old was administered 0.1 mL of the infected blood sample intraperitoneally once on the first day of the test. This malaria usually causes mice to die about 9 days after infection. Next, 200 μL of Ochrobactrum sp. 34-29 strain or Serratia sp. 44-1 strain culture extract with one-tenth addition of 220 mM phosphate buffer (pH 7.4) (final concentration 22 mM) is administered for the first time. The mice were administered once a day intraperitoneally daily from the next day. Cut 0.5mm of the infected mouse's tail with scissors for medical use and smear a drop of blood obtained from the cut tail on a slide glass. Malaria lab manual (Kazuaki Tanabe, “Malaria lab lab manual” 1st edition, Nana Publishing Co., Ltd., November 15, 2000, p23-24) After Giemsa staining treatment, the number of malaria-infected red blood cells and total red blood cells were measured by microscopic observation with an oil immersion lens. The malaria infection rate was calculated from the ratio of the number of malaria-infected red blood cells to the total number of red blood cells. Using chloroquine as a positive control, 200 μL of a chloroquine solution adjusted to 5 g / L in 22 mM phosphate buffer (pH 7.4) was administered once a day from the day after administration of the infected blood sample. Moreover, the extract which adjusted the culture medium which has not culture | cultivated the microbe by the method similar to Example 1 was used as negative control. The result of this experiment is shown in FIG. In the negative control mice, malaria parasites could be confirmed in the blood from the 5th day of infection, and then the infection rate increased every day, and on the 9th day, the malaria infection rate reached 50% and died (FIG. 1). The death of the negative control mice is shown as a cross). On the other hand, the mice administered with the positive control chloroquine, Ochrobactrum sp. 34-29 strain or Serratia sp. 44-1 culture extract had a malaria infection rate of 10% or less until 9 days after infection. Therefore, it is considered that the culture obtained by culturing Ochrobactrum sp. 34-29 and Serratia sp. 44-1 suppresses the growth of the malaria parasite by inhibiting heme polymerization of the malaria parasite. Accordingly, it can be presumed that Oklobactrum sp. 34-29 and Serratia sp. 44-1 are producing inhibitors that suppress the growth of the malaria parasite by inhibiting the heme polymerization of the malaria parasite.

It is a figure which shows the relationship between the days after infection in a lethal malaria infection mouse | mouth, and an infection rate.

Claims (15)

  A bacterium belonging to either the genus Ochrobactrum or Serratia that produces a suppressor that suppresses the growth of Plasmodium.   The bacterium according to claim 1, wherein the inhibitory substance inhibits the growth of the malaria parasite by inhibiting the heme polymerization of the malaria parasite. The bacterium according to any one of claims 1 and 2, wherein the bacterium belonging to the genus Ochrobactrum is Ochrobactrum FERM P-21915 strain.   The bacterium according to claim 1 or 2, wherein the bacterium belonging to the genus Serratia is Serratia FERM P-21914 strain.   A therapeutic agent for malaria comprising, as an active ingredient, a culture obtained by culturing a bacterium belonging to the genus Oklobactrum or Serratia.   The agent for treating malaria according to claim 5, wherein the growth of the malaria parasite is suppressed by inhibiting heme polymerization of the malaria parasite.   The therapeutic agent for malaria according to claim 5 or 6, wherein a supernatant fraction of the culture is used as an active ingredient.   The malaria therapeutic agent according to any one of claims 5 to 7, wherein the bacterium belonging to the genus Ochrobactrum is Ochrobactrum FERM P-21915 strain.   The malaria therapeutic agent according to any one of claims 5 to 7, wherein the bacterium belonging to the genus Serratia is Serratia FERM P-21914 strain.   A method for producing a therapeutic agent for malaria, comprising at least a step of collecting a culture obtained by culturing a bacterium belonging to the genus Oklobactrum or Serratia.   The method for producing a therapeutic agent for malaria according to claim 10, wherein the bacterium belonging to the genus Ochrobactrum is Ochrobactrum FERM P-21915 strain.   The method for producing a therapeutic agent for malaria according to claim 10, wherein the bacterium belonging to the genus Serratia is Serratia FERM P-21914 strain.   A method for producing a therapeutic agent for malaria, comprising at least a step of extracting a supernatant fraction from a culture obtained by culturing a bacterium belonging to the genus Oklobactrum or Serratia, and collecting the supernatant fraction.   14. The method for producing a therapeutic agent for malaria according to claim 13, wherein the bacterium belonging to the genus Ochrobactrum is Ochrobactrum FERM P-21915 strain. The method for producing a therapeutic agent for malaria according to claim 13, wherein the bacterium belonging to the genus Serratia is Serratia FERM P-21914 strain.

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