ANAEROBIC ENVIRONMENT

BY SREEREMYA.S

Also microaerophiles like Campylobacter jejuni very important in medial terms

For proper diagnosis and for studies of anaerobic environments culture techniques are desirable

Culture of anaerobes is extremely difficult due to the need to exclude oxygen, slow growth and complex growth requirements

Molecular methods based on DNA analysis and direct microscopy have shown that we are largely ignorant of the microbial world and previously unknown diversity has been discovered

Culture methodsAnaerobes differ in their sensitivity to oxygen

and the culture methods employed reflect this - some are simple and suitable for less sensitive organisms, others more complex but necessary for fastidious anaerobes

Vessels filled to the top with culture medium can be used for organisms not too sensitive

Most common adaptation of media is the addition of a reducing agent, e.g. thioglycollate, cysteine

Acts to reduce the oxygen to water, brings down the redox potential -300mV or less.

Can add a redox indicator such as rezazurin, pink in the presence of oyxgen - colourless in its absence

Deep culture tubes can be used to test whether an unknown organism is anaerobic/facultative or aerobic

Thioglycollate added to culture medium, oxygen only found near top where it can diffuse from air -pattern of colony formation characteristic of organisms

REDOX POTENTIAL