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What does oxidase do?

Oxidase is an enzyme that catalyzes oxidation-reduction reactions, especially one involving dioxygen (O2) as the electron acceptor. In reactions involving the donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydrogen peroxide (H2O2).

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What is oxidase and catalase?

Most aerobic and facultatively anaerobic bacteria have catalase!

Oxidase + (Ox +) means that the bacterium has cytochrome c oxidase as a terminal enzyme in the respiratory chain. This enzyme catalyzes the conversion of oxygen to water in the presence of cytochrome c and protons.

Catalase + (Cat +) means that the bacterium has catalase, which converts hydrogen peroxide to oxygen and water.

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Clostridium 1

obligate anaerobes, catalase (-)

facultative anaerobes, catalase (-)

obligate aerobes, catalase (+)

found in: soil, sewage, sediments, human and animal digestive tracts

found on mucous membranes, digestive system, plan material, milk, meat

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Clostridium 2

heat-resistant spores: efficiency of thermal processes

pleomorphism (X, Y, coccoid)

pleomorphism (X, Y, bacilloid)

pathogenic species from the proteolytic group

may cause spoilage defects – color defects in meat e.g. greening

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Clostridium 3

use for the production of butyric acid and solvents (e.g. butanol, acetone, isopropanol) and hydrogen

production of bacteriocins

propionic acid fermentation: propionic acid, acetic acid, CO2

antimicrobial activity of following metabolites: lactic acid, acetic acid, H2O2, bacteriocins

production of dextran - produced in the glycocalyx covering the cells (synthetic blood plasma substitute, slime defects in food products)

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Clostridium 4

break down of sugars: saccharolytic clostridia

break down of proteins: proteolytic clostridia

production of bacteriocins: C. botulinum, C. perfringens, C. acetobutylicum

production of bacteriocins: C. sporogenes, C. butyricum

production of bacteriocins: C. botulinum, C. tetani

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Clostridium 5

Use in medicine: neurotoxins, botulinum-toxin-complex as a therapeutic agent

Use in medicine: metabolites of C. botulinum, C. tetani

Food spoilage: late blowing of cheese & unpleasant, pungent off-flavor of silage

Food spoilage: pungent off-flavor of silage & bulging of tin cans caused by gas

Food spoilage: early blowing of cheese & unpleasant, tangy-flavor of silage

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What happens during putrefaction in canned foods caused by Clostridia?

milk, meat, and fish together with blown can lead to defects and decarboxylation of amino acids