KR20120064958A - Medium for selection of salmonella typhimurium with improved capacity - Google Patents

Abstract

PURPOSE: A medium composition for selecting Salmonella Typhimurium is provided to enhance selectivity of Salmonella Typhimurium and to reduce false positive result. CONSTITUTION: A medium composition for selecting Salmonella Typhimurium contains D-arabinose. The composition additionally contains pH indicator of which color changes according to the pH concentration. The medium contains 3.8-7.2 wt% of D-xylose, 5.1-9.5 wt% of L-lysine, 7.9-13.9 wt% of lactose, 7.9-13.9 wt% of saccharose, 5.1-9.5 wt% of sodium chloride, 3-5.6 wt% of yeast extract, 7-13 wt% of sodium desoxycholate, 7-13 wt% of sodium thiosulfate, 0.8-1.6 wt% of ferric ammonium citrate, 16.8-26.8 wt% of agar, and 0.02-0.06 wt% of neutral red.

Description

Medium for selection of Salmonella Typhimurium with improved capacity}

The present invention is Salmonella typhimurium ( Salmonella) typhimurium ) relates to a medium composition for selective fractionation.

Salmonella is one of the major food poisoning bacteria, and it causes a lot of food poisoning through the media such as chicken, beef and pork. In particular, Salmonella typhimurium is the causative agent of typhoid fever.

Salmonella food poisoning is usually caused by livestock, milk, eggs, etc. that have Salmonella bacteria, salads, etc., susceptible to secondary infection from contaminated growth, etc. can also be a causal food. The most common cause foods in Korea are fish and shellfish and processed products, and meat and processed products, milk and dairy products.

The separation of Salmonella from food is important for food safety. Among the various methods for Salmonella separation, the use of selective fractionation media is the most widely used method. To date, various kinds of selective fractionation media have been developed, and XLD (xylose lysine desoxycholate agar) is the most widely used.

Xylose lysine desoxycholate agar (XLD) media distinguishes Salmonella from other microorganisms by using Salmonella's H ₂ S production and lactose-free fermentation. However, false positive to mistaken the characteristics of Salmonella is Proteus (Proteus) Proteus (Proteus) to the slave sheet bakteo (Citrobacter) on a culture medium due to its bell bakteo (Citrobacter) in longitudinal and sheet kinds such as the in Salmonella (false positive ) Shows a lot of results. This false positive result requires additional testing to discern Salmonella, which adds a lot of additional cost and labor.

On the other hand, recently, a number of chromogenic selective media for detecting Salmonella using fluorescent materials have emerged, which are simpler than conventional media, but have a low sensitivity and increase false negative results. have. In addition, because of the high price compared to the existing medium causes a problem that can be limited in use in the food industry.

Therefore, the development of a new medium capable of efficiently detecting Salmonella Typhimurium from other bacteria by increasing the discrimination ability is urgently needed.

The present invention is a new Salmonella typhimurium ( Salmonella) that can overcome the above problems Typhimurium ) The purpose is to develop and provide selective fractionation media.

In order to achieve the above object, the present invention provides a Salmonella Typhimurium selective fractionation medium composition, Salmonella typhimurium comprising D-arabinose (D-arabinose) ( Salmonella Typhimurium ) to provide a selective fractionation medium composition.

Hereinafter, the means for solving the problems of the present invention will be described in detail.

Conventional xylose lysine desoxycholate agar (XLD) media have distinguished Salmonella from other microorganisms in the gut, using the properties that Salmonella produces H ₂ S and does not ferment lactose.

Salmonella removes sodium thiosulfate from XLD media. By absorbing H₂Create S, generate H₂S reacts with ferric ammonium citrate on the XLD medium to turn the colony black, which is why Salmonella grows to black colony on the XLD medium, leading to other enteric microorganisms. Is easily distinguished from.

However, the properties as described above is Proteus (Proteus) species and if the strains in the medium exists because it represents a bakteo (Citrobacter) species sheet, bakteo (Citrobacter) determines paper with Salmonella as Proteus (Proteus) species and the sheet on a culture medium It can cause false positive results.

The present invention to solve the above problems, Salmonella typhimurium ( Salmone lla Typhimurium ) In the selective fractionation medium composition, the carbon source is characterized by including D-arabinose (D-arabinose).

D-arabinose is a substance that has never been used in conventional Salmonella Typhimurium selective fractionation media, and Salmone lla Typhimurium) mothana is not using it as a carbon source Proteus Billy's Mum (bakteo prune di (C. freundii) with P. mirabilis) and the sheet can be used. In the present invention, D-arabinose (D-arabinose) is added to the XLD medium, and as a result of experiments, Proteus mirabilis ( P. mirabilis ) and Citrobacter Prundi ( C. freundii ) are D-Ara As a result of lowering pH by using D-arabinose as a carbon source, the colony of the strain did not grow black, while Salmonella typhimurium ( Salmonella) Typhimurium ) did not use D-arabinose as its carbon source and still showed black colony appearance.

That is, when the microorganism uses the carbon source for growth, the acid is generated to lower the pH of the colony, and the low pH may inhibit the characteristics of the microorganism producing H ₂ S in the XLD medium. arabinose (D-arabinose), by adding on XLD medium, Proteus Mira Billy's bakteo pruned di (C. freundii) strain with (P. mirabilis) as carbon source and the sheet is a D- arabinose (D-arabinose) As a result of use, the pH of the colony is lowered, the production capacity of H ₂ S is inhibited and ultimately the colony does not turn black. Salmonella Typhimurium , on the other hand, does not use D-arabinose as its carbon source, so it still shows black colony color.

After all, the present invention is to inhibit the production of H ₂ S by lowering the pH as described above Salmonella tie blood bunch Titanium (Salmonella Typhimurium) and Di bakteo pruned by Proteus Mira Billy's (P. mirabilis) and sheets (C. freundii) I discerned.

On the other hand, preferably Salmonella typhimurium selective fractionation medium composition of the present invention preferably further comprises a pH indicator that changes color depending on pH, Salmonella typhimurium ( S. Typhimurium ) can be easily separated by colony color from intestinal microbial strains that exhibit a pH lowering with culture.

On the other hand, preferably, the Salmonella typhimurium selective fractionation medium composition of the present invention, D-xylose, L- lysine (L-lysine), lactose (lactose), saccharose (saccharose), Sodium chloride, yeast extract sodium desoxycholate, sodium thiosulfate, ferric ammonium citrate, agar, neutral red It may include.

In addition, more preferably, the Salmonella typhimurium selective fractionation medium composition of the present invention is D-arabinose 7.9-13.9 wt%, D-xylose 3.8-7.2 wt%, L L-lysine 5.1-9.5 wt%, lactose 7.9-13.9 wt%, saccharose 7.9-13.9 wt%, sodium chloride 5.1-9.5 wt%, yeast extract ) 3 to 5.6% by weight, sodium desoxycholate 7 to 13% by weight, sodium thiosulfate 7 to 13% by weight, ferric ammonium citrate 0.8 to 1.6% by weight, agar ( agar) 16.8 ~ 26.8% by weight, neutral red (neutral red) is preferably composed of 0.02 ~ 0.06% by weight.

As it described above, a multitude of Salmonella tie blood Titanium (S. Typhimurium) badges for selection fractional composition developed in this invention is selected from Salmonella tie blood fractionation medium bunch Titanium (S. Typhimurium) existing Salmonella tie blood bunch Titanium (S . Typhimurium) and effective to increase the selectivity of the fractionation Proteus Mira Billy's (P. mirabilis) and sheet bakteo pruned di (C. freundii) Salmonella tie blood bunch Titanium (S. Typhimurium) by solving the problem that was not sensible to do.

This effect reduces the false positive results of P. mirabilis and C. freundii , and the number of colonies that perform additional tests to confirm Salmonella. And significantly reduce the cost and time spent on Salmonella detection.

1 is a diagram showing colonies (colony) of Proteus mirabilis ( P. mirabilis ) and Citrobacter Prundii ( C. freundii ) cultured in the existing XLD medium and the medium of the present invention.
2 is a diagram showing the herd Salmonella tie blood help the fractionated state (Salmonella Typhimurium) and Proteus Mira Billy's bakteo pruned di (C. freundii) to (P. mirabilis) and the sheet in a culture medium of the present invention.

Hereinafter, the contents of the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited only to the following examples, and includes modifications of equivalent technical ideas.

Example  1: Salmonella typhimurium of the present invention ( Salmonella Typhimurium ) Preparation of Selective Media Composition

badge 1 L standard 7.5 g of D-arabinose, 3.75 g of D-xylose, 5.0 g of L-lysine, 7.5 g of lactose, 7.5 g of Saccharose, 5 g sodium chloride, 3.0 g yeast extract, 2.5 g sodium desoxycholate, 6.8 g sodium thiosulfate, 0.8 g the operation rules ammonium iron (ferric ammonium citrate), 15.0 g of agar (agar), 0.03 g of neutral Red was added to blood herd Salmonella tie (nutral red) Titanium (Salmonella Typhimurium ) was prepared for selective fractionation medium.

This composition is a modification of the composition of xylose lysine desoxycholate agar (XLD) medium, which has been used in the past, and D-arabinose is added as a carbon source and neutral red (phenol-red) instead of phenol-red as a dye. nutral red).

Experimental Example  1: D- on the badge Of arabinose  Salmonella typhimurium with addition Salmonella Typhimurium )and Citrobacter Prundi ( Citrobacter freundii ) And Proteus Mirabilis ( Proteus mirabilis )of Discernment  Measurement experiment

Food application experiments were performed on the xylose lysine desoxycholate agar (XLD) medium and the medium prepared in Example 1, which have been previously used to verify strain selectivity of the improved function.

Samples of chicken, beef and pork (25 g) were added to 225 ml of buffered peptone water (BPW) for 24 hours at 37 ° C, followed by xylose lysine desoxycholate agar (XLD) medium and the improved functionality prepared in Example 1. Diluted in the medium and smeared. After smearing, black colonies were taken and bacteria were identified using the API 20E system.

Sample Number of samples tested Number of samples showing false positive colonies
(Number of samples that produce false-positive colonies) XLD Badge Example 1 (XA medium) Chicken 30 30 One Ground beef 23 23 4 Ground pork 10 10 0

As a result of the measurement (Table 1), in the conventional XLD medium, a total of 63 food samples, not Salmonella but Proteus mirabilis (P. mirabilis) And Citrobacter Prundi (C. freundiiFalse positive results were obtained, whereas false positive results were obtained in only five samples in Example 1 medium.

1 is a diagram showing colonies of Proteus mirabilis ( P. mirabilis ) and Citrobacter Prundi ( C. freundii ) in the conventional XLD medium and Example 1 medium, Proteus mirabilis ( P . mirabilis), and while the bakteo pruned D (C. freundii) into a sheet to grow black colonies (colony), such as Salmonella, in example 1 in the culture medium Proteus Mira Billy's (P. mirabilis), and in sheet bakteo pruned D (C freundii ) appears as pink colony, not black.

Experimental Example  2: Salmonella typhimurium through the strain inoculation experiment ( S .  Typhimurium )of Selective fractional detection experiment

The amount of Salmonella in food samples, such as Taizhou (25g) avoid a bunch Stadium (S. Typhimurium), Proteus Billy's Mum (P. mirabilis) and then inoculated bakteo prune di (C. freundii) into sheets, 225ml of BPW (buffered The mixture was diluted in medium of Example 1 and plated in peptone water). All colonies were taken from the medium and identified using the 'API 20E system'.

Colony color Examined % Confirmed ^a Black colonies 34 34 (100.0) Pink colonies 58 0 (0.0) ^a Salmonella typhimurium confirmed using API 20 E test

As a result of the experiment (Table 2), all the bacteria growing in the black colony ( S. Typhimurium ) in Example 1 medium were identified as Salmonella typhimurium , and all the bacteria growing in the pink colony (Colony) were Proteus mummy P. mirabilis and Citrobacter prundii were identified.

Claims (4)

Avoid Salmonella Thai bunch Stadium (Salmonella Typhimurium ) for selective fractionation medium composition,
D- arabinose (D-arabinose) Salmonella tie blood bunch, comprising a step of including Titanium (Salmonella Typhimurium ) medium for selective fractionation.
The method of claim 1,
Salmonella typhimurium ( Salmonella) Typhimurium ) selection fractionation medium composition,
Salmonella typhimurium, characterized in that it further comprises a pH indicator that changes color depending on the pH ( Salmonella) Typhimurium ) medium for selective fractionation.
The method of claim 1,
Salmonella typhimurium ( Salmonella) Typhimurium ) selection fractionation medium composition,
D-xylose, L-lysine, lactose, saccharose, sodium chloride, yeast extract sodium desoxycholate ), Sodium thiosulfate, ferric ammonium citrate (ferric ammonium citrate), agar (agar), neutral red (neutral red) characterized in that it further comprises Salmonella Typhimurium Medium composition.
The method of claim 3,
Salmonella typhimurium ( Salmonella) Typhimurium ) selection fractionation medium composition,
7.9-13.9 wt% D-arabinose, 3.8-7.2 wt% D-xylose, 5.1-9.5 wt% L-lysine, lactose 7.9 ~ 13.9 wt%, saccharose 7.9 ~ 13.9 wt%, sodium chloride 5.1 ~ 9.5 wt%, yeast extract 3 ~ 5.6 wt%, sodium desoxycholate 7 ~ 13 wt%, sodium thiosulfate 7-13 wt%, ferric ammonium citrate 0.8-1.6 wt%, agar 16.8-26.8 wt%, neutral red 0.02-0.06 wt% Salmonella typhimurium, characterized in that consisting of ( Salmonella Typhimurium ) medium for selective fractionation.

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