L.8 Oxygen

Microaerophiles

Aerobic bacteria that prefer 2-10% oxygen rather than the 21% found in the atmosphere are microaerophiles. The lower oxygen concentration is necessary for their respiratory metabolism.

sanitizer

Agents that reduce microbial numbers to a safe level but do not completely eliminate all microbes are defined as ___

Brewer's Anaerobic Agar

An excellent solid medium for cultivating anaerobic bacteria, Brewer's Anaerobic Agar contains thioglycollate, a reducing agent, and resazurin, an oxygen indicator

Obligate (Strict) Aerobe

Bacteria in this subgroup must grow in oxygen because their metabolism requires oxygen. These bacteria carry out respiration in which oxygen is used as the terminal electron acceptor in the electron transport chain.

Obligate anaerobes ex.

Clostridium is an example of obligate anaerobes.

Facultative anaerobes ex.

Escherichia coli and Salmonella are examples of facultative anaerobes.

FTM

Fluid thioglycollate medium

FTM media test

Fluid thioglycollate medium is a rich liquid medium that supports the growth of both aerobic and anaerobic bacteria. FTM is composed of glucose, cystine, and sodium thioglycollate to reduce its oxidation/reduction potential. It also contains a dye called resaruzin.

Microaerophiles ex

Helicobacter pylori and Campylobacter are pathogens found in the human gastrointestinal tract where the oxygen levels are lower than 20%

bacteriostatic

If a particular agent only inhibits the growth of bacterial cells but does not kill them, we say that the agent is bacteriostatic

Obligate (Strict) Anaerobes

Obligate anaerobes are harmed or killed by oxygen. To survive, these bacteria must be cultured in conditions where oxygen has been totally eliminated. These organisms carry out fermentation, in which inorganic compounds, such as nitrates and sulfates, take the place of oxygen in electron transport as the terminal electron acceptor. Obligate anaerobes are found in the soil, the rumen of cattle, and in septic systems.

Obligate Aerobes ex.

Pseudomonas, Micrococcus, and many Bacillus.

Aerotolerant anaerobes ex.

Streptococci that produce cheese, yogurt, and sour cream through fermentation and the pathogen Streptococcus pyogenes(causes strep throat) are examples of aerotolerant anaerobes.

Aerotolerant anaerobes

These anaerobes tolerate oxygen and grow in its presence, but they do not require oxygen for energy production. They use only fermentation to produce energy.

Facultative anaerobes

This group of bacteria grows well in aerobic conditions, but can also grow anaerobically when oxygen is not available. Their flexible metabolism allows them to produce energy by carrying out respiration when oxygen is available (aerobic conditions), but if oxygen is not available they can produce energy via fermentation which does not require oxygen.

TGYA Shake

This medium, containing tryptone (protein), glucose, yeast extract, and agar, is not primarily used to cultivate anaerobes, but can be used to determine the oxygen requirements of various bacteria. It is inoculated in the liquefied state, shaken to mix the organisms throughout the medium, and allowed to solidify. After incubation, the location of growth in the tube allows you to determine the microorganism's oxygen requirements.

TGYA

Tryptone Glucose Yeast Agar

bacteriocidal

agents that kill bacteria

semi-synthetic

antibiotics are chemically altered to make them more effective in their mode of action.

synthetic

antimicrobials are chemically synthesized in the laboratory and are not produced by microbial biosynthesis

antimicrobial

antimicrobials are compounds that kill or inhibit microorganisms

antibiotics

are antimicrobials, usually of low molecular weight, produced by microorganisms that inhibit or kill other microorganisms

disinfectant

are chemical agents that are applied to inanimate objects such as floors, walls, and tabletops to kill microorganisms

antiseptics

are substances such as alcohol or betadine that inhibit microbial growth or kill microorganisms and are gentle enough to be applied to living tissue**DO NOT DESTROY ENDOSPORES

peroxidase

degrades H2O2

catalase

degrades H2O2 to O2 and water

Superoxide dismutase

super oxides are converted to O2 and H2O2 by ____