Introduction
Dr Suzuki explains the steps you will take to culture and identify the bacteria in the samples. Two of the four samples are known to contain bacteria.

If you would like more information about media for growth of microorganisms click on the link below.

Personal Study: Media Types for the Growth of Different Microorganisms

Use the following link to check your understanding of the different media types after reading the Personal Study.

Activity: Media Types

Step 1. Select culture media

Deciding what culture media to use for each sample can be very confusing. Max, the Senior Technician, suggests that you read the SOP: Agar Types for Different Samples which you will find in the Methods Manual in his office.

SOP: Agar Types for Different Samples

After reading the SOP undertake the following activity to select the agar types you will need to grow the microorganisms in Samples SL2004/1 (urethral) and SL2004/4 (food).

Activity: Select Agar

After selecting the correct agar types for Samples SL2004/1 (urethral) and SL2004/4 (food) you now proceed to plate out the samples on the correct media to culture pure colonies to assist you in identifying the microorganisms contained in the samples.

Step 2. Inoculate the media aseptically

Growth of microorganisms in an artificial medium (liquid or solid) is usually the first step in the identification of an unknown organism.

The three main aims of inoculation of media are:

• to grow only the organism or organisms that are present in the original sample and not introduce any adventitious agent (aseptic technique)
• to protect yourself, your co-workers and the environment from any pathogenic microbes (aseptic technique and safety rules)
• to grow the microbes in such a way that further testing can be performed on the isolates (growth conditions and testing requirements).

At SimuLab bacteria and fungi are grown in liquid broths and on solid (agar) media. Viruses can only be grown in living cells. Inoculating the media with the sample is the next step in processing. Each different type of media requires a different inoculation technique. This is briefly explained in the following table.

Sample Type	Media type	Inoculation method
		Add a loopful or drop of culture into a new sterile bottle of broth.
	Agar plates	Streak plate with a loop of inoculum.
		Add a loopful or drop of culture into a new sterile bottle of broth.
	Agar plates	Streak plate with a loop of inoculum.
	Cell culture	Inoculate fresh culture medium with a small volume of virus suspension or cells containing virus.

To find out more about the specific techniques used to transfer microorganisms to culture media read the following SOPs.

Use the following link to go to obtain the SOP: Inoculating Liquid and Solid Media from the Methods Manual.

SOP: Inoculating Liquid and Solid Media

When reading the SOP you might have noticed the term Aseptic Technique used. If you are unsure of what is meant by Aseptic Technique you should read the following SOP for background information about the technique.

SOP: Aseptic Technique

Now you should be prepared to perform the next step in today's work, which is to plate out the two samples that contain bacteria. The following link will give you a demonstration of the streaking technique for agar plates.

Study Notes: Streaking Technique

Samples SL2004/1 (urethral) and SL2004/4 (food) are to be grown on agar plates so they will need the streaking method of inoculation. Do the following activity to inoculate the agar plates with the inoculum from the sample SL2004/1 (urethral).

Activity: Inoculate Agar Plates

You repeat the streaking technique for sample SL2004/4 (food) and then the agar plates remain on the bench until you are ready to place them in the correct incubators.

Step 3. Inoculate the media aseptically

For growth to occur the incubation conditions must be correct for the particular microorganism. For example, sample SL2004/3 (water) is from an environmental site and to ensure all types of microorganisms are grown the culture media should be grown at both 24°C and 37°C.

If you would like more information about growth conditions of different micro-organisms click on the link below.

Personal Study: Growth Conditions of Different Microorganisms and Media Types

Media types are explained in more detail in the Personal Study: Media Types for the Growth of Different Microorganisms.

Now you should incubate the samples according to the direction given in the SOPs and other materials that have been presented previously. Use the link below to go to an activity to do this.

Activity: Incubate Media

To continue, click on this link: Task 2. Purifying cultures Where am I?