Notes:
1) Aseptic technique refers to carrying out a procedure under controlled conditions in a manner that will minimize the chance of contamination.
2) All manipulations must be carried out in a sterile cabinet. First, flame all caps and lids, tightly close all bottles and caps, remove materials from the hood, turn off gas, wash the hood surface, turn the UV light to disinfect.
3) There are two types of basix culture techniques:
- Liquid Culture- microbes are reared in test tube in a liquid medium. The liquid culture is the best to use when you want to increase the concentration of microbes or you want to grow motile microbes.
- Culture Plate- Liquid medium is poured to petri dish as a thin layer at the bottom plate and let it to solidified. Culture plate is best to use when you want to test the sensitivity of bacteria to antibiotic, estimate culture concentration from environmental samples and isolate individual colonies from environmental samples.
- Streak plate method
- Pour plate method
5) Special culture technique is used to culture anaerobic microbes. Anaerobic environment (no oxygen, will carbon dioxide) is created to culture anaerobic microbes. Therefore, we need gas pack, catalyst, indicator and reducing agent.
6) Special culture technique will be done in either anaerobic chamber or anaerobic jar. The purpose of gas pack is to use up the surrounding oxygen and replaces with carbon dioxide. Indicator is to make sure along the culture process will be no oxygen contaminant in the medium. The example of indicator are methylene blue and resazurin. Reducing agent is to react more rapidly with oxygen and remove the oxygen. The example of reducing agent are cysteine and thioglycholate.
7) Gas pack is a packet of chemicals( sodium bicarbonate and sodium borohydrate). Hydrogen and carbon dioxide are produced by the reaction of the chemicals with the water.
8) Palladium catalyst combine the oxygen in the jar with the hydrogen produced the chemical reaction and water is formed.
9) Deoxygenerator is made up of copper. It is also acts as oxygen indicator which will turn black when oxygen is present.
10) Anaerobes must culture in test tube and the test tube need to roll all the time when culturing anaerobes. It is to form a thin layer of agar medium on all of the test tube wall.
11) A new technique to provide anaerobic environment is by adding oxyrase into medium to reduces oxygen to water. This technique able to avoid the need for more cumbersome(large and heavy) apparatus.
12) Culture medium is a nutrient material prepared for the growth of microorganisms in a laboratory.
13) Inoculum are microbes that are introduced into a culture medium to initiate growth.
14) Culture are the microbes that grow and multiply in or on a culture medium.
15) There are many different types of culture media：
- Chemically defined media - The exact composition in the media is known.
- Complex media - The exact chemical composition in the media is not known.
- Liquid medium - The components of medium are dissolved in water and sterilised
- Semisolid medium - Medium which has added a gelling agent. e.g. agar and gelatin
- Selective media - media that contain agents that inhibit th growth of certain bacteria while permitting the growth of others. It is used to isolate specific organisms.
- Differential media - Media that contain indicators that react differently with different organisms. e.g. produce colonies with different colour, It it used to identify specific organisms.
- Enrichment media - provides nutrients that favor the growth of a particular bacteria but no others. The small number of desired bacteria will increased to detectable level, which means the desired bacteria will present in much larger numbers.
- Blood agar - Nutrient agar with 5 to 10% of horse blood which used to cultivate all the fastidious microorganisms.
- Deep-freezing - Culture is placed at temperature ranging from -50 degree celcius to -95 degree celcius after the addition of 10% glycerol. Storage under liquid nitrogen (-196 degree celcius) in the presence of 5% DMSO and glycerol are cryoprotectant.
- Lyophilisation ( Freeze-drying)- Suspension od microbes freeze at -54 degree celcius to -72 degree celcius, dehydrated while frozen and sealed in vials under vacumm. Such cells can be definitely kept in room temperature. Freeze-dryer is used in Lyophilisation.
My own explorace:
1) Mix culture is the culture which has more than one species of bacteria in a culture. We can use the loop to transfer the single desired bacteria colony to another to a new agar media. This culture is called subculture.
2) Resazurin is in pruple colour. It turns pink after boiled. If the medium free of oxygen, resazurin will turns colourless.
3) Bijou bottle is a cylindrical small glass bottle with a screw cap used as a inoculum medium holder.
4) On Eosin Methylene Blue, If E.coli is grown, it will become metallic green because EMB has been specifically design to encourage the growth of gram positive bacteria.
5) Nutrient agar is a general media for growing bacteria and potato dextrose agar is a general media for growing fungi.
6) Cryoprotectant is a substance used to protect biological tissue from freezing damage.
Reflection:
I like those culturing technique. These technique look like very easy but need to take note of every specific detail in order for successfully culture a desired bacteria. I have to understand these culturing teachnique very well because we going to do practical based on the culturing teachnique. Besides that, as a microbiology student, culturing teachnique are basic things that we should have to know. I saw a video in youtube which clearly explain about the steak plate method.
This is the link of the video:
https://www.youtube.com/watch?v=_1KP9zOtjXk
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