The microorganisms related to food & feed safety, preservation, and fermentation processes. Basics about those MO and information on quality and microbiological safety, the role of lactic acid bacteria, protective cultures...The fundamental aspects of the biologically viable methods for food and feed preservation.
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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).
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.
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
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
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)
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
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
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