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Mohammed laqqan. Categories Based Upon Oxygen Requirements. ? Aerobic bacteriaRequire oxygen as electron acceptor? Microaerophilic bacteria Require oxygen in reduced quantity (2-10%) ? Facultative bacteriaGrow either with or without oxygen? Anaerobic bacteriaBoth obligate and aerotolerant (A
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1. Anaerobic Bacteria
2. Mohammed laqqan Categories Based Upon Oxygen Requirements • Aerobic bacteria
Require oxygen as electron acceptor
• Microaerophilic bacteria
Require oxygen in reduced quantity (2-10%)
• Facultative bacteria
Grow either with or without oxygen
• Anaerobic bacteria
Both obligate and aerotolerant (Aerotolerant do not use aerobic metabolism but have some enzymes that detoxify toxic forms of oxygen)
3. Mohammed laqqan Methods for excluding oxygen 1. Fluid Thioglycollate Media (FTM)
supports aerobic & anaerobic bacteria.
Sodium thioglycollate: removes O2 from the medium
Resazurin as an oxidation reduction indicator. dye that turns pink in presence of O2
4. Mohammed laqqan
5. Mohammed laqqan 2- Anaerobic Jar Inoculate FTM tube :
B. subtilis or P. aeruginosa (strict aerobes)
S. pyogenes (microaerophile)
E. coli (facultative anaerobe)
C. sporogenes (strict anaerobe)
Place in anaerobic jar.
Incubate overnight at 37C.
6. Mohammed laqqan Anaerobic Jar
7. Mohammed laqqan Anaerobic Jar For this exercise, we use the GasPak anaerobic system. This system consists of a polycarbonate jar, a lid with a gasket to prevent air flow, a strip infused with methylene blue, and a pouch containing sodium borohydride, sodium bicarbonate, citric acid, and a palladium catalyst.
When water is added to the pouch, the sodium borohydride, sodium bicarbonate, and citric acid react to form hydrogen and carbon dioxide. The palladium catalyzes a reaction between the hydrogen and the oxygen within the jar; this reaction creates water, which forms as condensation on the inside of the jar.
Methylene blue is blue in the presence of oxygen but is colorless in an anaerobic environment. When the oxygen is converted to water and condensation forms on the side of the jar, the indicator strip will turn from blue to white.
8. Mohammed laqqan Candle jars The candle flame will consume most of the oxygen in the jar.
Produce an elevated level of carbon dioxide.
These conditions are ideal for the growth of microaerophilic organisms.
9. Mohammed laqqan Growing Microaerophilic Microbes
10. Mohammed laqqan Anaerobic Chambers The Vinyl Anaerobic Chambers provide a strict anaerobic atmosphere of 0-5 parts per million (ppm) using a palladium catalyst and hydrogen gas mix of 5%.
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End of lecture