ISOLASI KAPANG DAN KHAMIR

Summary

This script outlines a detailed procedure for aseptically testing samples with varying weights. The process includes steps for cleaning the sample packaging, preparing dilutions, and applying the plate method or spread plate technique to test for microbial growth. Samples are carefully homogenized and diluted before being incubated at 25°C for 2-3 days. If colonies are too dense, further culturing techniques are used to ensure proper growth for accurate results. The method ensures accurate, aseptic handling and provides clear guidelines for microbial analysis.

Takeaways

• 😀 Clean the packaging with 70% alcohol before testing the sample.
• 😀 Samples weighing less than 1 kg should have 100 grams taken for testing.
• 😀 Samples weighing between 1 kg and 4.5 kg should have 300 grams taken for testing.
• 😀 Samples weighing more than 4.5 kg should have 500 grams taken for testing.
• 😀 Weigh 25 grams of the sample to be tested and place it in a sterile container or sterile plastic.
• 😀 Add 225 ml of distilled water to create a 10^-1 dilution and homogenize the sample for 2-3 minutes.
• 😀 Take 1 ml from the 10^-1 dilution using a sterile pipette and transfer it to 9 ml of distilled water to create a 10^-2 dilution.
• 😀 Shake each dilution at least 25 times or use a vortex mixer for about 1 minute.
• 😀 For the agar plate method, pipette 1 ml from the final dilution into a sterile petri dish and add 12-15 ml of cooled PDA medium.
• 😀 After mixing, incubate the petri dish at 25°C for 2-3 days to allow colonies to grow.
• 😀 If the colonies are too dense, perform quadrant streaking to isolate them, and incubate for another 48 hours at 25°C.

Q & A

What is the first step in preparing the sample for testing?

The first step is to clean the packaging of the sample with 70% alcohol.

How should the sample be selected for testing?

The sample should be taken aseptically and randomly. The weight of the sample will determine the amount to be taken: 100 grams for samples under 1 kg, 300 grams for samples between 1 kg and 4.5 kg, and 500 grams for samples over 4.5 kg.

What is the amount of sample to be weighed for testing?

You should weigh 25 grams of the sample to be tested.

What is the next step after weighing the sample?

After weighing the sample, it should be placed into a sterilized container or a sterilized plastic bag.

How much distilled water should be added to the sample?

Add 225 mL of distilled water to the sample to create a 10^-1 dilution.

How should the sample be homogenized?

The sample should be homogenized using a stomacher for 2-3 minutes.

What should be done after homogenizing the sample?

After homogenizing, 1 mL of the 10^-1 dilution should be taken using a sterile pipette and transferred into 9 mL of distilled water to achieve a 10^-2 dilution.

How should the dilution be mixed?

Each dilution should be shaken a minimum of 25 times or mixed using a vortex mixer for approximately 1 minute.

What is the next dilution to be prepared after the 10^-2 dilution?

The next dilution is the 10^-3 dilution. This is prepared by transferring 1 mL of the 10^-2 dilution into 9 mL of distilled water.

What are the methods for plating the sample?

Two methods for plating are mentioned: the pour plate method, where 1 mL of the final dilution is pipetted into a sterilized petri dish and 12-15 mL of cooled PDA medium is added, and the spread plate method, where 0.1 mL of the final dilution is spread onto the solidified PDA medium.

How should the petri dishes be handled after adding the sample and media?

The petri dishes should be rotated left and right to mix the sample with the medium thoroughly.

What is the incubation condition for the samples?

The samples should be incubated in an upright position in an incubator at 25°C for 2-3 days.

What should be done if the colonies are too dense?

If the colonies are too dense, the next step is to use the quadrant streaking technique for further separation and incubate for an additional 24 hours.