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Ch. 6 - Microbiology

Microbial Growth

Tend to survive very well when food is completely cooked and is compounded when food is refrigerated, as in larger scale food prepping. Bacillus cereus endospores.
Temperature, pH, Osmotic pressure. Physical requirements for growth.
Carbon, Nitrogen, sulfur, and phosphorous. Trace elements, Oxygen, Organic growth factors. Chemical requirements for growth.
Minimum, Optimum, Maximum. Temperature for growth.
Cold-loving (-10 - 20 C). Psychrophiles.
Moderate-temperature-loving (10 - 50 C). Mesophiles.
Heat-loving ( Optimum 50 - 60 C). (40 - 72 C response to temp.). Thermophiles.
0 - 20 - 30 C. Cause food spoilage. Psychotrophs.
Optimum 80 C. (67 to 110 C response to temp.). Hyperthermophiles.
No significant growth below freezing. 0 to -30- C.
Refrigerator temperatures; may allow slow growth of spoilage bacteria, very few pathogens. 0 C.
Many bacteria survive; some may grow. 5 to 15 C.
Rapid growth of bacteria; some may produce toxins. 15 to 50 C.
Very slow bacterial growth. 50 to 60 C.
Temperatures in this range destroy most microbes, although lower temperatures take more time. 60 to 130 C.
Approximate temperature at which Bacillus cereus multiplies in rice. 15 to 43 C.
6.5 and 7.5. pH where most bacteria grow between.
5 and 6. pH where molds and yeasts grow between.
Grow in acidic environments. Acidophiles.
Hypertonic environments (higher in solutes than inside the cell) cause ___ due to high osmotic pressure? Plasmolysis.
Require high osmotic pressure (high salt). Extreme or obligate halophiles.
Tolerate high osmotic pressure. Facultative halophiles.
Under these conditions, the solute concentration in the cell is equivalent to a solute concentration. of 0.85% sodium chloride (NaCl). Cell in isotonic solution.
If the concentration of solutes such as NaCl is higher in the surrounding medium than in the cell (the environment is hypertonic), water tends to leave the cell. Growth of the cell is inhibited. Plasmolyzed cell in hypertonic solution.
Structural backbone of organic molecules. Carbon.
Component of proteins, DNA, and ATP. Nitrogen.
Used in amino acids, thiamine, and biotin. Sulfur.
Used in DNA, RNA, and ATP. Phosphorus.
Inorganic elements required in small amounts. Trace Elements.
Usually as enzyme cofactors. Cofactors join to what part of the enzyme to make the functional enzyme? Holoenzyme. Trace Elements.
Most bacteria decompose protein material for this source. Nitrogen.
Most bacteria decompose protein for this source. Sulfur.
A few bacteria use N2 in its fixation. Nitrogen.
Some bacteria use NH4+ or NO3– from organic material. Nitrogen.
Chemoheterotrophs use organic molecules as energy. Autotrophs use CO2. Carbon.
Some bacteria use SO42– or H2S. Sulfur.
Found in membranes. PO43– is a source of it. Phosphorus.
Include iron, copper, molybdenum, and zinc. Trace Elements.
Found in hot springs and organic compost. Thermophiles.
Only aerobic growth; Oxygen required. Obligate aerobes.
Grow via fermentation or anaerobic respiration when oxygen is not available. Facultative anaerobes.
Unable to use oxygen and are harmed by it. Obligate anaerobes.
Tolerate but cannot use oxygen. Aerotolerant anaerobes.
Only aerobic growth; require oxygen concentration lower than air. Microaerophiles.
Only anaerobic growth; growth continues in presence of oxygen. Aerotolerant anaerobes.
Only anaerobic growth; growth cease in presence of oxygen. Obligate anaerobes.
Both aerobic/anaerobic growth; Greater growth in presence of oxygen. Facultative anaerobes.
Growth occurs only where high concentrations of oxygen have diffused into the medium. Obligate aerobes.
Growth is best when most oxygen is present, but occurs throughout tube. Facultative anaerobes.
Growth occurs only when there is o oxygen. Obligate anaerobes.
Growth occurs evenly; Oxygen has no effect. Aerotolerant anaerobes.
Growth occurs only where a low concentration of oxygen has diffused into the medium. Microaerophiles.
Presence of enzymes catalase and superoxidize dismutase (SOD) allows toxic forms of oxygen to be neutralized; can use oxygen. Obligate aerobes.
Presence of enzymes catalase and SOD allows toxic forms of oxygen to be neutralized; can use oxygen. Facultative anaerobes.
Lacks enzymes to neutralize harmful forms of oxygen; cannot tolerate oxygen. Obligate anaerobes.
Presence of one enzyme catalase, SOD, allows toxic forms of oxygen to be partially neutralized; tolerates oxygen. Aerotolerant anaerobes.
Produce lethal amounts of toxic forms of oxygen if exposed to normal atmospheric oxygen. Microaerophiles.
(1 O2−) boosted to a higher-energy state and is reactive Singlet oxygen.
O2- + O2- + 2H+ -> H2O2 + O2 Superoxide radicals.
2 H2O2 -> 2 H2O + O2 = H2O2 + 2H ->2H2O Peroxide anion.
(OH•). Hydroxyl radical.
Organic compounds obtained from the environment. Vitamins, amino acids, purines, and pyrimidines. Organic Growth Factors.
Microbial communities. Form slime or hydrogels that adhere to surfaces. Bacteria communicate cell-to-cell via quorum sensing. Share nutrients. Shelter bacteria from harmful environmental factors. Can migrate. Biofilms.
Found in digestive system and sewage treatment systems; can clog pipes. 1000x resistant to microbicides. Involved in 70% of infections. Catheters, heart valves, contact lenses, dental caries. Biofilms.
Nutrients prepared for microbial growth. Culture medium.
No living microbes. Sterile.
Introduction of microbes into a medium. Inoculum.
Microbes growing in or on a culture medium. Culture.
Complex polysaccharide. Used as a solidifying agent for culture media in Petri plates, slants, and deeps. Generally not metabolized by microbes. Liquefies at 100C. Solidifies at ~40C. Agar.
Exact chemical composition is known. Fastidious organisms are those that require many growth factors provided in this media. Chemically defined media.
Extracts and digests of yeasts, meat, or plants; chemical composition varies batch to batch. Nutrient broth* Nutrient agar* *Theses are primarily what we use in our lab. Complex media.
Glucose, Ammonium phosphate, monobasic, Sodium chloride, Magnesium sulphate, Potassium phosphate, dibasic, Water. Chemically defined media for Chemoheterotroph, (E. coli.).
Carbon and energy, salts, Amino acids, Purines ans Pyrimidines, Vitamins, trace elements, Buffer, Distilled water. Defined culture medium for Leuconostoc mesenteroides.
Peptone, Beef extract, Sodium chloride, Agar, water. Complex medium for the growth of heterotropic bacteria.
Used for the cultivation of anaerobic bacteria. Contain chemicals (sodium thioglycolate) that combine O2 to deplete it. Heated to drive off O2. Reducing media.
Microbes that require high CO2 conditions. CO2 packet. Candle jar. Capnophiles.
No special precautions; basic teaching labs. Organisms that do not normally cause disease in healthy humans. Biosafety Level 1.
Lab coat, gloves, eye protection*. Organisms that can cause disease but unlikely via aerosol and there is a known treatment. Biosafety Level 2.
Biosafety cabinets to prevent airborne transmission. Organisms that can cause lethal disease via aerosol but there is a known treatment. Biosafety Level 3.
Sealed, negative pressure; "hot zone". Exhaust air is filtered twice through HEPA filters. Organisms that can cause lethal disease via aerosol and where there is no know cure. Biosafety Level 4.
Suppress unwanted microbes and encourage desired microbes. Contain inhibitors to suppress growth. Selective media.
Allow distinguishing of colonies of different microbes on the same plate. Some media have both selective and differential characteristics. Differential media.
Encourages the growth of a desired microbe by increasing very small numbers of a desired organism to detectable levels. Usually a liquid. Enrichment Culture.
Growth of chemoautotrophs and photoautotrophs; microbiological assays. Chemically defined.
Growth of most chemoheterotropic organisms. Complex.
Growth of obligate anaerobes. Reducing.
Suppression of unwanted microbes; encouraging desired microbes. Selective.
Differentiation of colonies of desired microbes from others. Differential.
Similar to selective media but designed to increase numbers of desired microbes to detectable levels. Enrichment.
Contains only one species or strain. Pure culture.
A population of cells arising from a single cell or spore or from a group of attached cells. Often called a ___-forming unit (CFU) Colony.
Used to isolate pure cultures. Streak plate method.
–50 to –95 C. Deep-freezing preservation.
Frozen (–54 to –72 C) and dehydrated in a vacuum. Lyophilization (freeze-drying).
Increase in number of cells, not cell size. Binary fission. Budding. Conidiospores (actinomycetes). Fragmentation of filaments. Bacterial Division.
Cell elongates and DNA is replicated. Cell wall and plasma membrane begin to constrict. Cross-wall forms, completely separating the two DNA copies. Cells separate. Binary fission in bacteria.
Time required for a cell to divide (20 minutes to 24 hours). Binary fission doubles the number of cells each generation. Total number of cells = 2 number of generations. Growth curves are represented logarithmically and arithmethically. Generation Time.
Log 10 of 32 (5th generation). 1:51.
Lag phase, Log phase, Stationary phase, Death phase. Phases of Growth.
Intense activity preparing for population growth, but no increase in population. Lag phase.
Logarithmic or exponential increase in population (due to reproduction by binary fission - bacteria or mitosis - yeast). Log phase.
Period of equilibrium; microbial deaths balance production of new cells. Stationary phase.
Population is decreasing at a logarithmic rate. Death phase.
Plate count, Filtration, Most probable number (MPN) method, Direct microscopic count. Direct Measurement of Microbial Growth.
To ensure the right number of colonies, the original inoculum must be diluted via serial dilution (9 ml broth in each tube). Plate counts dilution.
Counts are performed on bacteria mixed into a dish with agar (pour plate method) or spread on the surface of a plate (spread plate method). How are plate counts performed.
Count colonies on plates that have 30 to 300 colonies (CFUs). Number of colonies on plate.
Solution passed through a filter that collects bacteria. Filter is transferred to a Petri dish and grows as colonies on the surface. Filtration.
Multiple tube test. Count positive tubes. Compare with a statistical table. Most Probable Number (MPN) Method.
Volume of a bacterial suspension placed on a slide. Average number of bacteria per viewing field is calculated. Uses a special Petroff-Hausser cell counter. Direct Microscopic Count.
Number of bacteria/ml = Number of cells counted x Volume of area counted. 17,000,000 = 14 cells x 1,250,00 ml (per square) Petroff-Hausser cell counter.
Measurement of cloudiness with a spectrophotometer. Turbidity.
Amount of metabolic product is proportional to the number of bacteria. Metabolic activity.
Bacteria are filtered, dried, and weighed; used for filamentous organisms. Dry weight.
Process in which bacteria responds to the density of a nearby bacteria. Quorum Sensing.
Use carbon dioxide as a carbon source and use light as an energy source. Photoautotrops.
Acquire energy from light and acquire nutrients via catabolism of organic compounds. Photoheterotrophs.
Enzyme that breaks hydrogen peroxide into water. Peroxidase.
Acquire electrons from organic sources. Organotrophs.
Salt-loving bacteria. Halophiles.
Graph that plots the number of bacteria growing in a population over time. Growth curve.
Phase of the bacterial growth curve where generation time is constant. Exponential growth.
An enzyme that degrades hydrogen peroxide to release water and oxygen. Catalase.
Organisms that live under extreme pressure. Barophiles.
Organisms that live in alkaline soil and water up to pH 11.5. Alkalinophiles.
Created by: Jpereira72



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