Media may be either a liquid medium or a solid medium. Liquid culture media are very useful for growing large numbers of microorganisms. Solid media can be used to purify a microbial culture or to ensure its purity. Media is made solid by addition of Agar (~1.5%). Agar is an extract of seaweed.
A pure culture contains only one species of microorganism. When studying microorganisms, pure cultures are normally required.
A culture that is not pure may be either contaminated culture or a mixed culture. A contaminated culture is one where one or more unwanted types of microorganisms have been allowed to grow. This is not good! A mixed culture is one in which two or more microorganism are intentionally mixed. Yogurt starter is an example of a mixed culture.
Yogurt starter = Lactobacillus bulgaricus +
Streptococcus thermophilus, for example.
The link in the third bulleted point shows the use of chemicals. The spray bottle contains 70% ethyl alcohol. It also shows the use of UV light and highly filtered air. Both have a good presentation of sterile techniques.
Aseptic Technique
Aseptic means “free of microorganisms”. A synonymous term is “sterile technique”.
When studying or working with microorganisms, it is essential that cultures remain pure. We use clean techniques to ensure that pure cultures are not contaminated. These techniques involve:
• Heating tools and media,
• Use of chemicals to clean tools and surfaces, and,
• Use of highly filtered air.
• Use of UV light
The link in the first bulleted point shows the streak plate technique. Note the use of flame.
Media may be either a liquid medium or a solid medium. Liquid culture media are very useful for growing large numbers of microorganisms. Solid media can be used to purify a microbial culture or to ensure its purity. Media is made solid by addition of Agar (~1.5%). Agar is an extract of seaweed.A pure culture contains only one species of microorganism. When studying microorganisms, pure cultures are normally required. A culture that is not pure may be either contaminated culture or a mixed culture. A contaminated culture is one where one or more unwanted types of microorganisms have been allowed to grow. This is not good! A mixed culture is one in which two or more microorganism are intentionally mixed. Yogurt starter is an example of a mixed culture. Yogurt starter = Lactobacillus bulgaricus +Streptococcus thermophilus, for example.The link in the third bulleted point shows the use of chemicals. The spray bottle contains 70% ethyl alcohol. It also shows the use of UV light and highly filtered air. Both have a good presentation of sterile techniques.Aseptic TechniqueAseptic means “free of microorganisms”. A synonymous term is “sterile technique”.When studying or working with microorganisms, it is essential that cultures remain pure. We use clean techniques to ensure that pure cultures are not contaminated. These techniques involve:• Heating tools and media,• Use of chemicals to clean tools and surfaces, and,• Use of highly filtered air.• Use of UV lightThe link in the first bulleted point shows the streak plate technique. Note the use of flame.
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