Method for detecting coliform

A coliform and concentration technology, which is applied in the preparation of test samples, color/spectral characteristic measurement, and resistance to vector-borne diseases, etc., can solve the problem of inability to accurately measure low-concentration colonies, multi-scenario detection application limitations, and difficult To achieve the ideal effect and other problems, to achieve the effect of low reagent price, few types, and low cost-effectiveness ratio

Pending Publication Date: 2022-05-27
SOUTH CHINA UNIV OF TECH
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Problems solved by technology

This makes this type of detection method have greater instability, and the detection limit is high, and it is impossible to accurately measure low-concentration colonies
In addition, due to the complex composition of the food matrix, it is difficult to achieve the desired effect in detecting the number of bacteria in the food matrix. Therefore, many of these reports do not involve the detection and analysis of colonies in food samples, which has great limitations in the application of multi-scenario detection.

Method used

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  • Method for detecting coliform
  • Method for detecting coliform
  • Method for detecting coliform

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] The compounds of the present invention with good effect of inducing the expression of coliform β-galactosidase are screened. Select the following compound combinations (lactose, low-concentration glucose and IPTG can be induced): lactose (0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0g / L), glucose (0.5, 1.0, 1.5, 2.0, 2.5 , 3.0, 4.0, 5.0g / L), lactose and glucose (mixed in equal amounts of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0g / L), the preparation solvents were pure water, physiological saline (SPSS) ), SPSS+IPTG, PBS and PBS+IPTG five groups of solvents. The five groups of solvents were mixed with X-Gal to form a detection solution system. The concentration of IPTG added was 0.024g / L, and the concentration of X-Gal was 0.2g / L, and then the bacterial liquid was added and mixed (Escherichia coli ATCC25922), The bacterial concentration is 1.0×10 7 CFU / mL, cultured in a 37°C incubator shaker. The induction effect of different induction systems on coliform was determined. All r...

Embodiment 2

[0054] Screening of SPSS+IPTG and PBS+IPTG

[0055] In order to further verify the color rendering effect of SPSS+IPTG and PBS+IPTG detection systems, the bacterial concentration (Escherichia coli ATCC 25922) in both SPSS+IPTG and PBS+IPTG detection systems was 1×10 6 CFU / mL, IPTG concentrations were all 0.024g / L, and X-Gal concentrations were all 0.2g / L. Response appropriate time, record OD 655nm , see the results figure 2 .

[0056] figure 2 It shows that under the same conditions, the bacterial concentration is 1 × 10 6 In CFU / mL, PBS+IPTG was better than SPSS+IPTG, and the color rendering effect was better. Therefore, the PBS+IPTG detection system was selected.

Embodiment 3

[0058] Optimization of PBS+IPTG detection system

[0059] Further experiments found that in the 24h incubation time, the detection system of PBS+IPTG (without YET) in Examples 1 and 2 could only make the bacterial concentration 1.0×10 at the highest. 4 CFU / mL detection system color development (OD 655nm =0.030), wherein the IPTG concentration in the detection system was 0.024g / L, and the X-Gal concentration was 0.2g / L. The concentration of bacterial liquid after 24 hours was detected by plate counting method, and it was found that the number of bacterial colonies in the detection system decreased significantly after culturing for 24 hours, indicating that the bacteria died in the process of inducing color development. It is speculated that there may be antibacterial substances or Lack of nutrients makes the bacteria unable to maintain vitality in the detection system for a long time, and eventually some bacteria die, resulting in the inability to develop normal color. Theref...

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Abstract

The invention belongs to the field of detection of coliforms, and particularly discloses a method for detecting coliforms, and a detection solution system in the method comprises the following components by mass: a phosphate buffer solution, yeast extract powder, 5-bromo-4-chloro-3-indole-beta-D-galactopyranoside and isopropyl-beta-D-thiogalactoside. The method specifically comprises the following steps: adding a to-be-detected sample into the detection solution system (IPTG-YET-X-Gal), and calculating the number of coliforms in the to-be-detected sample by measuring OD655nm and combining the standard curve of the method. The method disclosed by the invention can be used for simply and conveniently detecting the coliform in foods such as water, fruit juice and milk, and provides guarantee for the safety quality of the foods. In addition, the method disclosed by the invention is slightly influenced by an external environment, is good in stability, can be used for sample adding operation on site, can adapt to various detection environments and does not need specific laboratory conditions.

Description

technical field [0001] The invention belongs to the field of detection of coliform bacteria, and particularly relates to the field of detection of coliform bacteria in food (water, fruit juice, milk, etc.). Background technique [0002] Coliforms are grouped into different genera, mainly based on the bacteria's ability to ferment lactose. However, coliforms are often described as Gram-negative, rod-shaped Enterobacteriaceae that ferment lactose to produce acids and gases. Coliform bacteria mainly exist in the feces of humans and animals, and can be used as an indicator of fecal contamination to evaluate the hygienic status of food, so as to infer the possibility of contamination by enteric pathogens in food. Coliforms are generally considered harmless, but some typical coliform strains such as Escherichia coli O157:H7, Klebsiella pneumoniae, and Citrobacter freundii are pathogenic to humans. The risk of infectious disease transmission in public health settings has attracte...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/31G01N1/38
CPCG01N21/31G01N1/38Y02A50/30
Inventor 肖性龙刘西敏王璐莹李晓凤余以刚
Owner SOUTH CHINA UNIV OF TECH
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