What are six categories of harmful microorganisms?
Microbes are organisms that are too small to be seen by the human eye and include bacteria, archaea, protists, viruses, and fungi.
What are the 6 conditions for bacterial growth?
FAT TOM is a mnemonic device used in the food service industry to describe the six favorable conditions required for the growth of foodborne pathogens. It is an acronym for food, acidity, time, temperature, oxygen and moisture.
What 4 conditions are needed for bacteria to grow?
What bacteria need to grow and multiply
- Food (nutrients)
- Water (moisture)
- Proper temperature.
- Time.
- Air, no air, minimal air.
- Proper acidity (pH)
- Salt levels.
What are the two conditions for bacterial growth that you can control?
Bacteria can live in hotter and colder temperatures than humans, but they do best in a warm, moist, protein-rich environment that is pH neutral or slightly acidic.
What is the most resistant form of bacterial life?
A variety of different microorganisms form “spores” or “cysts”, but the endospores of low G+C Gram-positive bacteria are by far the most resistant to harsh conditions.
What are the 3 types of oxygen requirements in bacteria?
Available Oxygen
- Obligate Aerobes: oxygen required.
- Facultative: grow in the presence or absence of oxygen.
- Microaerophilic: grow best at very low levels of oxygen.
- Aerotolerant Anaerobes: oxygen not required for growth but not harmful if present.
What are the oxygen requirements for bacteria?
The oxygen level has to be just right for growth, not too much and not too little. These microaerophiles are bacteria that require a minimum level of oxygen for growth, about 1%–10%, well below the 21% found in the atmosphere.
What do anaerobic bacteria need to survive?
An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environment.
Which bacteria would grow at the bottom of a thioglycollate tube?
Aerobic and anaerobic bacteria can be identified by growing them in test tubes of thioglycolate broth:
- Obligate aerobes need oxygen because they cannot ferment or respire anaerobically.
- Obligate anaerobes are poisoned by oxygen, so they gather at the bottom of the tube where the oxygen concentration is lowest.
What is the name of the process by which bacteria are placed in media where they will be able to grow?
culture
What is the purpose of fluid thioglycollate medium?
Fluid Thioglycollate Medium is a general purpose liquid enrichment medium used in qualitative procedures for the sterility test and for the isolation and cultivation of aerobes, anaerobes and microaerophiles that are not excessively fastidious.
Where would you predict an facultative anaerobe would grow in a tube of fluid thioglycollate medium?
Facultative or aerotolerant anaerobes can grow throughout the medium but will primarily grow in the middle of the tube, between the oxygen-rich and oxygen-free zones.
Why do anaerobes fail to grow in the presence of atmospheric oxygen?
Obligate anaerobes cannot tolerate oxygen because they utilize metabolic schemes built around enzymes that react with oxidants. The reliance upon low-potential flavoproteins for anaerobic respiration probably causes substantial superoxide and hydrogen peroxide to be produced when anaerobes are exposed to air.
Why does a facultative anaerobe grow better when oxygen is present?
Facultative anaerobes can change their metabolic processes depending on the presence of oxygen, using the more efficient process of respiration in the presence of oxygen and the less efficient process of fermentation in the absence of oxygen.
Which of the following is an example of a biofilm?
Biofilms are a collective of one or more types of microorganisms that can grow on many different surfaces. Microorganisms that form biofilms include bacteria, fungi and protists. One common example of a biofilm dental plaque, a slimy buildup of bacteria that forms on the surfaces of teeth. Pond scum is another example.
What are the 5 stages of biofilm formation?
Biofilm formation can be divided into five stages: Initial reversible attachment (1), irreversible attachment (2-3), maturation (4) and dispersion (5) as shown in Figure 2.
What are the four stages of biofilm formation?
Biofilm formation is commonly considered to occur in four main stages: (1) bacterial attachment to a surface, (2) microcolony formation, (3) biofilm maturation and (4) detachment (also termed dispersal) of bacteria which may then colonize new areas [2].
What is the function of a biofilm?
Biofilms are multi-cellular communities formed by bacteria, and they consist of bacteria encased within a non-crystalline extracellular matrix (ECM) of proteins, polysaccharides, and small molecules. Biofilm formation provides increased protection of bacteria from antibiotics and host defenses.
Which is a major function of a biofilm infection?
The biofilm bacteria can share nutrients and are sheltered from harmful factors in the environment, such as desiccation, antibiotics, and a host body’s immune system. A biofilm usually begins to form when a free-swimming bacterium attaches to a surface.
What are the characteristics of biofilms?
What are key characteristics of biofilms?
- Biofilms are complex, dynamic structures.
- Genetic expression is different in biofilm bacteria when compared to planktonic bacteria.
- Biofilm cells can coordinate behavior via intercellular “communication” using biochemical signaling molecules.
- Biofilms are less susceptible to antimicrobial agents.
How is biofilm beneficial to bacteria?
Biofilm formation is considered a virulence determinant in microorganisms, and it strongly contributes to microbial resistance to conventional antimicrobial agents, host protective immune responses, hostile environmental pressures/stresses, predation, and shear forces.