What is Pseudomonas Aeruginosa? Preservation Methods Explained

News 30 9 月, 2024

1. What is Pseudomonas Aeruginosa?

Pseudomonas aeruginosa, previously known as Bacillus pyocyaneus, is a widespread bacterium found in nature. It is one of the most common bacteria in soil and can be present in various environments, such as water, air, human skin, respiratory tracts, and intestines. This bacterium thrives in moist conditions and is classified as a non-fermenting Gram-negative rod.

Pseudomonas aeruginosa is a well-known opportunistic pathogen, with cells that are slender and vary in length. They sometimes appear as coccobacilli or linear rods and often arrange in pairs or short chains. It grows within a temperature range of 25-42°C, with an optimal growth temperature of 25-30°C. Notably, the bacterium does not grow at 4°C but can grow at 42°C, a characteristic that aids in its identification.

It can grow on ordinary culture media and produces water-soluble pigments like pyocyanin and fluorescein. On blood agar plates, it forms clear hemolytic rings around the colonies.

2. Important Considerations for Preparing Pseudomonas Aeruginosa Contaminated Carriers

Standard strains of Pseudomonas aeruginosa are commonly used in disinfection efficacy evaluation tests for products like water disinfectants and disinfection equipment. Since Pseudomonas aeruginosa differs from other common bacteria, there are some specific considerations to keep in mind:

• During the drying process at 37°C, the bacterial load can decrease significantly (up to one logarithmic level). Therefore, the initial concentration of the Pseudomonas aeruginosa suspension should be increased to ensure the required bacterial load is met.
• Prepare the contaminated carriers freshly and use them immediately. Avoid storing them for extended periods.

3. Preservation Methods for Pseudomonas Aeruginosa

Slant Preservation Method:
Pseudomonas aeruginosa is prone to death when stored in a refrigerator’s cold compartment. Therefore, it is best to store its slant culture tubes at room temperature. Using an inoculating needle, transfer a small amount of the bacterial colony onto a slant culture tube and incubate it at 37°C for 18 hours. After incubation, store the tube at room temperature for further use.

Ultra-Low Temperature Glycerol Preservation Method:

1. Inoculate Pseudomonas aeruginosa into a sterile broth and incubate at 37°C for 18 hours in an incubator.
2. Add sterile glycerol to the culture to achieve a final concentration of 15% glycerol. Mix thoroughly.
3. Dispense 1 mL of the mixture into sterile cryogenic vials or 1.5 mL centrifuge tubes, sealing the lids tightly.
4. Place the tubes in a -20°C freezer for 3 hours, then transfer them to a -70°C freezer for long-term preservation.