How to Test Textiles for Microbes

Microbes, such as bacteria and fungi, can cause deterioration and odor in textile materials, as well as skin irritations on the person in contact with them. Many textile manufacturers now apply an antimicrobial finish and treatment onto the textile to help prevent the growth on microbes. However, laboratory testing on the antimicrobial textiles is necessary to ensure that the finish and/or treatments are working and that there is no deterioration in the textile material itself.

Things You'll Need

• Bacteria samples
• Fungal inoculum samples
• Textile samples
• Agar plates
• Petri dish
• Incubator
• Humidity chamber
• Vermiculite
• Distilled water
• Test tube or beaker

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Instructions

Agar Diffusion Method

• 1

  Inoculate an agar plate with bacteria and incubate the plate for 24 hours.

• 2

  Put a piece of the textile directly on the surface of the agar plate. Incubate the agar plate again for 24 hours.

• 3

  Examine the plate for any microbial growth. Textiles that have been treated or contain an antimicrobial agent should not show bacterial growth on the textile. There should be a large zone of inhibition on the plate (i.e., the bacteria moves into the agar and away from the textile material).

Cell Suspension Test

• 4

  Directly place bacteria onto the textile itself. You can use a petri dish without agar for this method.

• 5

  Wait 24 hours and rinse the bacteria from the fabric using distilled water into a test tube or beaker. Transfer the bacterial solution onto an agar plate and incubate for 24 hours.

• 6

  Count the number of colonies that have formed on the textile within the 24-hour time period. If the antimicrobial finish or treatment is working on the textile, you will see a decrease in the number of bacteria. An increase in bacteria growth suggests that the antimicrobial and treatment are not effective.

• 7

  Repeat this procedure in different temperature environments such as hot, cold, humid, and dry, to ensure the lack of bacterial growth in various environments.

Humidity Chamber for Fungal Growth

• 8

  Inoculate a piece of the textile with fungal inoculum and place into a humidity chamber set at 90 percent humidity. Make sure you put the sample on a piece of moist vermiculite.

• 9

  Incubate the textile for 28 days at a temperature of 20 degrees Celsius.

• 10

  Examine the textile for any fungal growth. You can examine with the naked eye, as the fungal growth can be visually seen.