JP3584251B2 - Halo photographing apparatus and halo photographing method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a halo photographing apparatus and a halo photographing method. More specifically, the present invention relates to an apparatus and a method for imaging a halo of a colony of bacteria (particularly, Listeria, Bacillus cereus, Staphylococcus aureus, etc.) formed on an agar medium. Here, a colony is a colony formed on an agar medium as a result of division and growth of bacteria, and a halo is a turbid zone formed around a bacterial colony. .
[0002]
[Prior art]
Foods are obligated to determine the presence of contamination indicator bacteria and food poisoning bacteria by bacterial inspection in accordance with official law. Such a method of bacterial inspection is defined as an official law and an inspection guideline in the “Food Sanitation Law” and “Food Sanitation Inspection Guidelines / Microorganisms” under the supervision of the Ministry of Health, Labor and Welfare. In the inspection according to the official method and the inspection guidelines, a specimen is smeared on an agar medium filled in a petri dish, and after culturing for a certain period of time, the contamination indicator bacteria and food poisoning bacteria are determined by a qualitative or quantitative test.
[0003]
On the other hand, in typical food poisoning bacteria Listeria, Bacillus cereus, Staphylococcus aureus, etc., it is known that a halo is formed around the colony, and a specific agar medium corresponding to each bacterium was used. In that case, it is known that halo formation is specific to each bacterium. Therefore, halo discrimination has an important significance in judging the presence or absence of these halo-forming food poisoning bacteria.
[0004]
[Problems to be solved by the invention]
However, since the halo is extremely thin at the beginning of the culture, it is difficult to visually distinguish the halo early with the conventional apparatus and method. Accordingly, an object of the present invention is to provide a halo photographing apparatus and a photographing method for photographing a halo clearly and early after culturing, and an object of the present invention is to construct a system capable of judging a result of a bacterial test at an early stage.
[0005]
[Means for Solving the Problems]
In the halo imaging apparatus according to claim 1 of the present application, a petri dish filled with an agar medium for detecting bacteria from a specimen is disposed between a camera and a transmission light source having a white and uniform planar shape. The first shield that can adjust the position of the transmission light source so that the distance between the light source and the petri dish is a predetermined distance, and shields the parts other than the petri dish so that the light from the transmission light source does not hit the parts other than the petri dish A plate is disposed at substantially the same height as the petri dish, and shields a region other than a region having a predetermined size outside the projection region of the transmission light source as viewed from the camera of the petri dish. The plate is arranged close to the transmission light source.
[0006]
The halo photographing device according to claim 2 of the present application, wherein the shielding region of the second shielding plate is larger than the projection region of the transmission light source as viewed from the camera by a predetermined dimension. A third shielding plate for shielding an area smaller than the third area is disposed close to the transmission light source.
[0007]
A halo photographing device according to a third aspect of the present invention is the device according to the first aspect, wherein the predetermined distance between the transmission light source and the petri dish is 5 to 15 cm.
[0008]
A halo photographing device according to a fourth aspect of the present invention is the device according to the third aspect, wherein the predetermined distance between the transmission light source and the petri dish is 10 cm.
[0009]
The halo photographing device according to claim 5 of the present application is the device according to any one of claims 1 to 4, wherein the predetermined size of the second shielding plate is 0 to 3 cm. is there.
[0010]
A halo photographing apparatus according to a sixth aspect of the present invention is the apparatus according to the fifth aspect, wherein the predetermined size of the second shielding plate is 1 cm.
[0012]
The halo imaging method according to claim 7 of the present application provides a first step of disposing a culture dish inoculated with a sample between a camera and a transmission light source having a white and uniform planar shape; A second step of adjusting the position of the transmission light source so that the distance becomes a predetermined distance, a third step of shielding a portion other than the petri dish so that light from the transmission light source does not impinge on a portion other than the petri dish, A fourth step of shielding an area other than an area having a predetermined size outside the projection area of the petri dish viewed from the camera of the light source, and illuminating and photographing the petri dish with a transmission light source to obtain a first image; And 5 stages.
[0013]
The halo photographing method according to claim 8 of the present application is the method according to claim 7 , wherein each of the transmission light sources is larger than a projection area of the petri dish viewed from the camera by a predetermined size and is larger than a shielding area in the fourth stage. And a seventh step of illuminating and photographing the petri dish with a transmission light source to obtain a second image.
[0014]
A halo imaging method according to a ninth aspect of the present invention is the method according to the seventh or eighth aspect , wherein the predetermined distance between the transmission light source and the petri dish is 5 to 15 cm.
[0015]
According to a tenth aspect of the present invention, in the halo imaging method according to the ninth aspect , the predetermined distance between the transmission light source and the petri dish is 10 cm.
[0016]
The halo imaging method according to claim 11 of the present application is the method according to any one of claims 7 to 10 , wherein the predetermined distance in the fourth step is 0 to 3 cm. is there.
[0017]
A halo imaging method according to a twelfth aspect of the present invention is the method according to the tenth aspect , wherein the predetermined distance in the fourth step is 1 cm.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, a halo photographing apparatus according to a preferred embodiment of the present invention will be described with reference to the drawings. A halo photographing apparatus according to a preferred embodiment of the present invention, which is generally indicated by reference numeral 10 in FIG. The camera 12 is typically of a CCD type, but a camera of another type may be used. The camera 12 is attached to a vertical pole 16 fixed to a base 14 via an arm 18 as shown in FIG.
[0020]
The halo imaging device 10 also includes a transmission light source 20. As shown in FIG. 1, the transmission light source 20 is attached to a vertical pole 22 fixed to the base 14 via a support 24 so as to be able to move up and down. That is, the support 24 supporting the transmission light source 20 is configured to move vertically along the rail 26 attached to the vertical pole 22 by using the driving force of the motor 28. Since such elevating means itself is known, a detailed description thereof will be omitted.
[0021]
The transmission light source 20 is a white and uniform planar light source, and is preferably formed of a white light emitting diode adjusted to have a uniform luminance.
[0022]
The halo imaging apparatus 10 further includes a petri dish 30 filled with an agar medium for detecting bacteria from a specimen. A petri dish 30 having a circular planar shape is attached to the vertical pole 16 via an arm 32. According to experiments performed by the present inventors, the distance between the transmission light source 20 and the petri dish 30 is preferably 5 cm to 15 cm, and most preferably 10 cm. The distance between the transmission light source 20 and the petri dish 30 is appropriately adjusted by using the above-described elevating means.
[0023]
The halo photographing device 10 further includes a first shielding plate 34 attached at a position substantially at the same height as the petri dish 30. The first shielding plate 34 has an opening 34 a having a plane shape substantially the same as the plane shape of the petri dish 30, so that light from the transmission light source 20 does not reach the camera 12 from a location other than the petri dish 30. Help to make. The provision of the first shielding plate 34 prevents light hitting the side wall and the like of the petri dish 30 from being irregularly reflected.
[0024]
The halo photographing device 10 further includes a second shielding plate 36 mounted immediately below the transmission light source 20. The second shielding plate 36 has an opening 36 a having a size to be described later, and serves to adjust the amount of light of the transmission light source 20.
[0025]
The opening 36a of the second shielding plate 36 desirably has such a size as to minimize unevenness in luminance in the image of the petri dish 30. As a result of various experiments, the inventor has found an opening 36a having an optimal size for photographing a halo. Now, as shown in FIG. 2, assuming that the distance between the camera 12 and the petri dish 30 is L1, the distance between the petri dish 30 and the transmission light source 20 is L2, and the diameter of the petri dish 30 is D, the camera of the petri dish 30 in the transmission light source 20 12, the diameter E of the projection area is represented by E = D × (L1 + L2) / (L1), and the size of the opening 36a is E + 2X. Our experiments have shown that X is preferably between 0 and 3 cm, most preferably 1 cm.
[0026]
The halo imaging apparatus 10 further includes a third shielding plate 38 mounted immediately below the transmission light source 20, as shown in FIG. The third shielding plate 38 has a diameter E + 2Y that is slightly larger than the diameter E of the projection area viewed from the camera 12 of the petri dish 30 (see FIG. 4). According to experiments performed by the present inventors, Y is preferably 0 to 1 cm. The third shielding plate 38 serves to prevent the petri dish 30 from being directly illuminated. Note that the third shielding plate 38 must be smaller than the opening 36a of the second shielding plate 36.
[0027]
A method of photographing a halo using the halo photographing apparatus 10 configured as described above will be described. First, the petri dish 30 is filled with an agar medium, and a sample is smeared, and then cultured for a certain time. Next, the distance L2 between the petri dish 30 and the transmission light source 20 is set to 5 to 15 cm, and the first shielding plate 34 and the second shielding plate 36 are arranged and photographed to obtain a first image (first image). Then, the whole petri dish is bright and the halo is relatively dark). Next, in addition to the above-described state, shooting is performed with the third shielding plate 38 arranged, and a second image is obtained (in the second image, the entire petri dish is darkened, and the halo is relatively brightly displayed. ).
[0028]
The first and second images obtained as described above are processed as follows. An image is created in which the absolute value of the difference between the respective density values of the same coordinate pixels of the first image and the second image is set as a pixel value, and this is set as a third image. Similarly, an image is created in which the absolute value of the difference between the respective density values of the same coordinate pixels of the inverted image of the first image and the second image is a pixel value, and this image is defined as a fourth image. By performing image processing in this manner, halos are clearly displayed.
[0029]
The present invention is not limited to the above embodiments of the invention, and various modifications can be made within the scope of the invention described in the claims, which are also included in the scope of the invention. Needless to say, it is.
[0030]
For example, in the above embodiment, the petri dish 30 is shown as having a circular planar shape, but a petri dish having a rectangular planar shape may be used. Further, in the above-described embodiment, the distance L2 between the light source 20 and the petri dish 30 is configured to be mechanically adjustable. However, the distance L2 may be manually adjusted.
[0031]
【The invention's effect】
According to the present invention, with the conventional apparatus and method, it is possible to obtain a clear image of a halo that was difficult to visually distinguish early in the cultivation, and thereby it is possible to obtain a halo-forming food poisoning bacterium. Presence / absence and the number thereof can be accurately determined.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a halo photographing apparatus according to a preferred embodiment of the present invention.
FIG. 2 is a diagram showing dimensions of a shielding plate in FIG. 1;
FIG. 3 is a diagram showing a state where a third shielding plate is arranged in FIG. 1;
FIG. 4 is a diagram showing dimensions of a shielding plate in FIG. 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Halo imaging device 12 Camera 14 Base 16, 22 Vertical pole 20 Transmission light source 30 Petri dish 34 First shielding plate 36 Second shielding plate 38 Third shielding plate

Claims (12)

An apparatus for photographing a halo formed around a bacterial colony,
A Petri dish filled with an agar medium for detecting bacteria from a specimen is arranged between the camera and a transmitted light source having a white and uniform planar shape, so that a distance between the transmitted light source and the Petri dish becomes a predetermined distance. The position of the transmission light source can be adjusted
A first shielding plate for shielding a portion other than the petri dish so that light from the transmission light source does not hit a portion other than the petri dish is disposed at a position substantially at the same height as the petri dish,
A second shielding plate for shielding an area other than an area having a predetermined size outside the projection area as viewed from the camera of the petri dish in the transmission light source is arranged close to the transmission light source,
An apparatus characterized in that: A third shielding plate, which shields an area larger than the shielding area of the second shielding plate by a predetermined size outside the projection area of the petri dish viewed from the camera in the transmission light source, is close to the transmission light source. The device of claim 1, wherein the device is arranged. The apparatus according to claim 1, wherein the predetermined distance between the transmission light source and the petri dish is 5 to 15 cm. The apparatus according to claim 3, wherein the predetermined distance between the transmission light source and the petri dish is 10cm. The device according to any one of claims 1 to 4, wherein the predetermined dimension of the second shielding plate is 0 to 3 cm. The apparatus according to claim 5, wherein the predetermined dimension of the second shielding plate is 1cm. A method of photographing a halo of a bacterial colony,
A first stage of disposing a culture dish inoculated with a sample between a camera and a transmission light source having a white and uniform planar shape;
A second step of adjusting the position of the transmission light source so that the distance between the transmission light source and the petri dish is a predetermined distance;
A third stage of shielding a portion other than the petri dish so that light from the transmitted light source does not hit the portion other than the petri dish;
A fourth step of shielding regions other than regions each having a predetermined size outside the projection region of the transmission light source viewed from the camera of the petri dish;
Illuminating and photographing the petri dish with a transmission light source to obtain a first image. A sixth step of shielding an area larger than the projection area as viewed from the camera of the petri dish in the transmission light source by a predetermined dimension and smaller than the shielding area in the fourth step;
The method according to claim 7 , further comprising: illuminating and photographing the petri dish with a transmission light source to obtain a second image. 9. The method according to claim 7 , wherein the predetermined distance between the transmission light source and the petri dish is 5 to 15 cm. The method according to claim 9 , wherein the predetermined distance between the transmission light source and the petri dish is 10cm. The method according to any one of claims 7 to 10 , wherein the predetermined dimension in the fourth step is 0 to 3 cm. The method of claim 11 , wherein the predetermined dimension in the fourth step is 1cm.

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