Escherichia Coli Water Analysis

Escherichia coli can cause gastrointestinal infections or localized tissue and organ infections in humans and animals under certain conditions, and is a common foodborne pathogen in humans. In recent years, the number of cases of human food poisoning caused by E. coli contaminated water is increasing, and this contaminant poses a great safety risk to drinking water quality.

Technologies for Testing E. coli

Multi-tube fermentation technology, membrane filtration technology, enzyme-linked immunoassay, gene chip technology, and high performance liquid chromatography.

Detection Range

Detection of E. coli in surface water, groundwater, wastewater, sewage, drainage water and sea surface water.

Interfering Substances in the Detection Process

• The water sample contains substances that inhibit or promote the growth of E. coli bacteria.
• The glassware and equipment used for testing contain substances that inhibit or promote the growth of E. coli bacteria.
• Water samples with high turbidity may cause blockage of membrane pores or diffuse growth of bacterial colonies (Spreading) and affect the observation of water samples and interpretation of results.

Testing Services

BOC Sciences can provide the following steps for testing E. coli in water by the membrane method.

1. The water sample must be shaken vigorously before testing or dilution to mix the sample well.
2. Use a sterile pipette to absorb the water sample into the sterile dilution solution to form a 10 times dilution of the water sample, mixed well. And then from the 10 times dilution of water samples, the same operation to 100, 1000, 10000 times the dilution of water samples, and mixed well.
3. Pick up the sterile filter membrane and put it on the perforated plate of the sterile filtration device. Add sterile dilution solution to determine whether the filtration equipment is properly installed.
4. Suck up the original solution and each dilution of water samples to the sterile filter and filter.
5. After rinsing and filtering, remove the filter cup and place the filter membrane on the culture medium by clamping it, the membrane should be completely attached to the culture medium to avoid air bubbles.
6. Place the Petri dish upside down in the incubator and incubate at 35 ± 1℃ for 24 ± 2 hours.
7. Count the colonies produced in each dilution of the Petri dish and record.

Caution

• If the solution appears foreign matter or turbidity, it should not be used anymore.
• If the water sample has to be diluted, it is recommended to complete the test procedure within 30 minutes after dilution to avoid bacterial death or proliferation, which may affect the test results.
• Whenever a colony appears metallic, whether the metallic luster covers the entire colony or only a small portion of the center of the colony, the colony is considered to be E. coli bacteria.
• If according to the historical data or water sample characteristics, the water sample has a high turbidity condition, or the expected number of miscellaneous bacteria on the filter membrane may be the number of metallic luster colonies If the water sample has a high turbidity condition, or the expected colony count on the membrane may be more than 10 times of the metallic luster colony count, the water sample can be filtered by more than 2 membranes, and the metallic luster colony count can be summed up after incubation to reduce the interference.

In addition to E. coli detection by filter membrane method, we can also provide other types of detection techniques for analysis and testing, if you are interested in our services, please do not hesitate to contact us at any time.