LSM 3232 practical 2- ResultsNutritional requirements for growth of bacteria - Oxygen Requirements

MicroorganismsAerobic Anaerobic Microaerobic

Observed Expected Observed Expected Observed ExpectedEscherichia coli(facultative anaerobic) + + + + + +

Clostridium perfringens(Strict anaerobic but can adapt to oxygen for short periods)

- - + + + +

Pseudomonas aeruginosa(Aerobic, can survive in microaerobic conditions)

+ + - - + +

CampyGen sachet: When a CampyGen sachet is placed in a sealed jar, the atmospheric oxygen in the jar is rapidly absorbed with the simultaneous generation of carbon dioxide, producing the appropriate microaerobic conditions.

AnaeroGen sachet:Where an AnaeroGen sachet is placed in a sealed jar, the atmospheric oxygen in the jar is rapidly absorbed with the simultaneous generation of carbon dioxide.

Ref: http://www.oxoid.com/UK/blue/prod_detail/prod_detail.asp?pr=CN0025&org=154&c=UK&lang=EN

Clostridium perfringens, a strictly anaerobic bacterium, is able to survive when exposed to oxygenfor short periods of time and exhibits a complex adaptive response to reactive oxygen species (chemically reactive molecules containing oxygen), both under aerobic and anaerobic conditions.

Ref: Oxidative stress response in Clostridium perfringens , Microbiology (2004), 150, 1649–1659

Pseudomonas aeruginosa (extracted from Wikipedia)Although classified as an aerobic organism, P. aeruginosa is considered by many as a facultative anaerobe, as it is well adapted to proliferate in conditions of partial or total oxygen depletion. This organism can achieve anaerobic growth with nitrate as a terminal electron acceptor, and, in its absence, it is also able to ferment arginine by substrate-level phosphorylation.1,2 Adaptation to microaerobic or anaerobic environments is essential for certain lifestyles of P. aeruginosa, for example, during lung infection in cystic fibrosis patients, where thick layers of lung mucus and alginate surrounding mucoid bacterial cells can limit the diffusion of oxygen.

Ref:1. Membrane-bound nitrate reductase is required for anaerobic growth in cystic fibrosis sputum, J. Bacteriol. (2007), 189, 4449-44552. Pseudomonas aeruginosa mutants affected in anaerobic growth on arginine: evidence for a four-gene cluster encoding the arginine

deiminase pathway, J. Bacteriol. (1984), 160, 928-934