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Measurement of salmonella bacteria – provided by Kagome Co., Ltd. –

Series: Ernestly measurement

Measurement of salmonella bacteria – provided by Kagome Co., Ltd. –

Food poisoning salmonella bacteria develop an infection on intestinal epithelial cells and cause gastroenteritis.
Although the number of cases is decreasing in recent years, food poisoning incidents caused by this bacteria are often reported by news programs.
We examined salmonella bacteria using a mobile PCR device.

Sample

Salmonella (strains Sal A, B) culture specimen (salad 10 g + pre-culture medium 90 mL)

Pretreatment

Detection sensitivity check:

  1. Strain Sal A and strain Sal B were inoculated in salad materials (10 g) + medium (90 mL of buffered peptone water).
  2. They were cultured at 37 degrees Celsius for 24 hours.

Measurement of cultured suspension via direct PCR:

  1. 3.4 pieces of strain Sal A and 1.5 pieces of strain Sal B were inoculated in salad materials (10 g) + medium (90 mL of buffered peptone water).
  2. They were cultured at 37 degrees Celsius.
  3. Samples were obtained at specified times and exposed to boiling water for 5 min.
Program
Process Temperature Time
Initial denaturation 95℃ 15sec
Annealing/extension 60℃ 15sec 45cycle
Denaturation 95℃ 4sec
Results

[First step: Creation of a calibration curve]
Sample
Cultured suspension (direct PCR)
Pretreatment

  1. Strain Sal A and strain Sal B were inoculated in salad materials (10 g) + medium (90 mL of buffered peptone water).
  2. They were cultured at 37 degrees Celsius for 24 hours.
  3. 1 μL of supernatant of the cultured suspension was used as the template.

The number of bacteria after the culture was calculated using the same sample.

[Second step: Measurement of cultured suspension via direct PCR]
Sample
Cultured suspension (direct PCR)
Pretreatment

  1. 3.4 pieces of strain Sal A and 1.5 pieces of strain Sal B were inoculated in salad materials (10 g) + medium (90 mL of buffered peptone water).
  2. They were cultured at 37 degrees Celsius.
  3. Samples were obtained at specified times and exposed to boiling water for 5 minutes. Then, 1 μL of supernatant was used as the template.

This study result was presented by Kagome Co., Ltd. and NSG Group at 39th annual conference of the Japanese Society of Food Microbiology.