JP4074261B2 - Method for producing photodegradable agricultural chemical composition - Google Patents

Description

  The present invention relates to a method for producing a photodegradable agrochemical composition, and more particularly, to a method for producing a photodegradable agrochemical composition in which an agrochemical active ingredient is degraded with light over time.

  In modern agriculture, chemical pesticides have played a major role in improving productivity. However, excessive use of chemical pesticides disrupts the ecosystem and causes problems for the human environment, such as food safety concerns caused by residual pesticides. For these reasons, development of agricultural chemicals with low toxicity and persistence is desired.

Recently, microbial pesticides have been actively developed as pesticides having no toxicity or persistence. For example, Patent Document 1 discloses a method of using a microorganism that removes pests and improves soil, and is particularly resistant to temperature and chemicals, and is suitable as a microorganism suitable for removing pests and improving soil. It has been proposed to use the soil treatment fungus S5. Further, Patent Document 2 discloses a microbial pesticide having a plant surface fixing ability, using a filamentous fungus Verticillium lecani having a function of parasitic insects and killing insects as a pest parasitic fungus.
JP 2000-197477 A (Claims etc.) JP 2003-335612 A (Claims etc.)

  However, since microbial pesticides are composed mainly of microorganisms such as live cells, dead cells, dry cells, and spores, they should be handled in the same way as conventional general chemical pesticides in terms of formulation. Was difficult. That is, microbial pesticides have problems in their preparation and spraying methods, and have not always been easily put into practical use.

  Accordingly, an object of the present invention is to provide a method for producing a novel agrochemical composition having no toxicity and persistence in place of a microbial agrochemical.

  In order to solve the above-mentioned problems, the inventors of the present invention have made extensive research efforts and pursued by screening a pesticide active ingredient that can be a residual pesticide and a reduced pesticide, and found an antimicrobial substance that is photodegradable by sunlight. The present invention has been completed.

  That is, this invention is a manufacturing method of the photodegradable agricultural chemical composition characterized by including the process of culture | cultivating MS02-063 strain which belongs to the genus Hahera in a nutrient medium, and producing a prodigiosin pigment.

  The present invention cultivates the above-mentioned microorganism belonging to the genus Hahella that produces prodigiosins, and has found that the culture supernatant has antibacterial activity against pathogenic plant bacteria and is easily decomposed by sunlight. It is based on.

  Prodigiosins, which are active ingredients in the photodegradable agricultural chemical composition of the present invention, are useful as therapeutic agents for inhibiting the infection of phytopathogenic fungi, especially powdery mildew and black rot. Moreover, since it decomposes easily by sunlight, it does not remain as a residual pesticide and is an extremely safe pesticide. Therefore, spraying pesticides in the evening or at night shows pesticide activity at night and prevents infection against phytopathogenic fungi, while remaining easily on the field because it is easily degraded by sunlight during the day There is nothing.

Hereinafter, embodiments of the present invention will be specifically described.
The active ingredient of the photodegradable agricultural chemical composition of the present invention is a red pigment of prodigiosins, which is a representative pigment produced by Serratia marcescens. In addition to Serratia, these prodigiosins include Vibrio (Int J Syst Evol Microbiol. 2003 Mar; 53 (Pt2): 479-84) and Pseudoarteromonas (Biochem Biophys Res Commun. 28; 237 (3). : 543-7 (1997)), actinomycetes (Antimicrob Agents Chemother. 46 (4): 1112-1113 (2002)), etc., are known to produce.

で表されるプロジギオシンの他、次式（ＩＩ）、

で表されるシクロプロジギオシンも含まれ、さらにこれらの塩酸塩、リン酸塩、硫酸塩、過塩素酸塩等、各種塩類も含まれる。 Prodigiosins that are active ingredients of the photodegradable agricultural chemical composition of the present invention include the following formula (I),

In addition to prodigiosin represented by the following formula (II),

In addition, various salts such as hydrochloride, phosphate, sulfate, perchlorate and the like thereof are also included.

  Obtaining a standard product of such prodigiosins has been difficult until now, but the present inventors have discovered a microorganism that produces a large amount of prodigiosin pigments, and have completed the production method of the present invention.

  The strain MS02-063 belonging to the genus Hahella used in the method of the present invention is a yeast / malt agar seawater medium (yeast extract 0.4%, malt extract 1%, It was obtained by culturing with dextrose 0.4%, agar 1.5%, 50% artificial seawater) and separating the formed colonies.

  The prodigiosin-producing microorganism MS02-063 strain thus obtained is a non-fermentative negative bacillus and has no motility. It also has the ability to produce cells with zoospores. This bacterium does not produce a pigment at the initial stage of culture (about 12 hours of culture), and then rapidly produces a red pigment. Moreover, since it was alive in the brackish water area, about 0.5% or more of salt is required. The mycological properties of the MS02-063 strain are shown in Table 1 below.

＊炭素源の資化性試験はバイオログシステムを使用した。

* The biolog system was used in the carbon source utilization test.

  The prodigiosin-producing microorganism MS02-063 strain of the present invention is a novel bacterium not disclosed in the literature, and is deposited at the Patent Organism Depositary under the deposit number FERM P-19635.

  The method for culturing such microorganism MS02-063 strain is not particularly limited. For example, colonies may be formed in a solid medium and the colonies may be cultured in a liquid medium. The medium used in the present invention can be used as long as it is a general nutrient medium. For example, YPG medium-30% artificial seawater (yeast extract 1.25%, peptone 1.25%, glucose 3%) is preferably used. can do.

  The culture temperature can be cultured from 15 ° C to 37 ° C, but is preferably 20 ° C to 30 ° C. Moreover, pH at the time of culture | cultivation is 5.5-10, Preferably it is pH 6.0-9.0. Furthermore, the salt concentration of the medium can grow at 0.5-3.0% as the amount of NaCl, but is preferably 0.5-1.5%, more preferably about 1%. The culture period produces a large amount of red pigment in one or more nights, and is preferably about 1.5 days, but the number of culture days is not limited.

  The following method for isolating and recovering the produced pigment is not particularly limited, and may be appropriately changed according to the form of the red pigment used, the type of the extraction solvent, and the like. For example, a solvent extract of a red pigment can be obtained by the following method. The detailed extraction procedure will be described in the following examples.

  First, the culture solution in which the colonies are cultured is preferably freeze-dried. Next, a red pigment is extracted by adding an appropriate extraction solvent to the obtained freeze-dried preparation. Examples of the extraction solvent used to obtain the red pigment include water, alcohols having 1 to 8 carbon atoms such as methanol, ethanol, propanol, and butanol, ester organic solvents such as chloroform and ethyl acetate, or water and the above-mentioned A mixed solution with alcohol can be mentioned, and alcohol is particularly preferably used, and methanol and ethanol are most preferably used. For extraction, for example, an appropriate amount of a desired extraction solvent is added to a freeze-dried preparation, subjected to ultrasonic treatment, and then centrifuged to obtain a supernatant. If necessary, an extraction solvent may be newly added to the residue, and the same method may be repeated once or twice for extraction.

  By subjecting the solvent extract obtained by the above method to a known separation and purification method such as column chromatography, the desired prodigiosins can be easily isolated.

  The formulation form of the photodegradable agricultural chemical composition of the present invention is not particularly limited, and an arbitrary dosage form such as a powder, a granule, a liquid, a granule aqueous solvent, an emulsion and the like may be appropriately selected according to the use. it can. Moreover, the photodegradable agricultural chemical composition of the present invention may be used as it is after adjusting the concentration of the culture supernatant containing prodigiosins to an appropriate concentration, without taking the form of an arbitrary dosage form.

Hereinafter, the present invention will be described in more detail based on examples, but it is needless to say that the present invention is not limited to such examples.
Prodigiosin-producing microorganism MS02-063 strain was cultured with shaking in YPG liquid medium at 28 ° C. for 3 days. 100% ethanol was added to the culture solution, and the cells were removed by centrifugation (3000 rpm, 20 minutes) to obtain an ethanol-extracted culture supernatant. An equal amount of 100% ethanol was added to the culture supernatant, extracted and condensed with ethyl acetate, the solvent extract was replaced with 50% methanol, and the absorption spectrum was measured. The absorption spectrum shown in FIG. 1 was obtained. From this absorption spectrum, it was found that the substance contained in the culture supernatant was a prodigiosin pigment.

  Next, 50 μL of the culture supernatant solution was impregnated into a thick pulp disk of φ8 mm, and ethanol was completely evaporated under reduced pressure. This supernatant-containing pulp disc is placed on an assay plate (Sabouraud agar medium) containing each test bacteria, and cultured for 1 to 7 days to inhibit the growth inhibitory activity against the test bacteria (pathogenic bacteria) shown in Table 1 below. It was measured by the size of the circle.

  Next, the culture supernatant solution was transferred to a glass container capable of being sealed and allowed to stand in the daytime under fine weather. The growth inhibition activity of the left sample was measured in the size of the inhibition circle by the same method as described above. The results are shown in Table 2 below.

  Subsequently, the photodegradability with respect to sunlight was measured by measuring the optical density (OD) in 536 nm which is the maximum absorption wavelength ((lambda) max) of prodigiosin dye. The results are shown in Table 3 below.

なお、上記表３中、０時間のＯＤ（５３６ｎｍ）を１００％とした。

In Table 3, the 0 hour OD (536 nm) was 100%.

  As seen in Table 3, it was found that the prodigiosin pigments were clearly inactivated by sunlight.

  The active ingredient compound in the present invention has an excellent anti-phytopathogenic action, has no persistence, and is useful as an agricultural chemical. That is, pesticides are sprayed in the evening or at night to obtain pesticide activity at night and are easily decomposed by sunlight during the day, so that they do not remain on the field. The use as an agrochemical in the present invention can be used not only for powdery mildew and black rot, but also for the treatment and prevention of plant diseases caused by pathogenic fungi and pathogenic yeasts. Moreover, the amount of the existing pesticide can be reduced by combining the pesticide of the present invention with the existing pesticide.

It is a graph which shows the absorption spectrum of the red pigment | dye refine | purified from the culture supernatant.

Claims (1)

  A method for producing a photodegradable agricultural chemical composition, comprising a step of culturing MS02-063 strain belonging to the genus Hahella in a nutrient medium to produce a prodigiosin pigment.

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