Microbial Growth Pt.3 Flashcards
What are cardinal temperatures? Describe the types.
the range of temperatures for the growth of a given microbial species;
Minimum temperature: the lowest temperature that permits a microbe’s continued growth and metabolism and below this temperature, its activities are limited
Maximum temperature: the highest temperature at which growth and metabolism can proceed before proteins are denatured
Optimum temperature: an intermediate between the minimum and the maximum that promotes the fastest rate of growth and metabolism (perfect temperature)
Explain the temperature requirements
Membrane fatty acid composition and protein composition differ with temperature requirements, if the membrane is in a liquid state the organism is alive and Thermophile has the optimal temperature
What the 2 main temperature ranges?
Stenothermal – grows in a narrow temperature range (most pathogens; usually in the equator or north poles)
Eurythermal – grows in a wide temperature range (most organisms)
Describe the different ways water concentration can effect cell growth
Organisms have to extract water from environment, ex. Salting of food or Jams and Jellies
Osmotolerant tolerates sugar concentration, ex. Xeromyces sp.
Osmophillic likes to grow in high sugar concentration, ex. Saccharomyces sp.
Halotolerant tolerant salt, ex. Staphylococcus aureus
Halophillic likes salt in high concentration and in extremes in high temperature, ex. Vibrio sp., Halobacterium sp.
What are the different effects of oxygen on cell growth?
Aerobic – requires oxygen, ex. Bacillus subtilis
Obligate Anaerobic – oxygen toxic, ex. Clostridium sporogenes, Methanococcus sp. , Bacteriodes sp. , Ruminococcus sp.
Facultative anaerobe – uses oxygen, anaerobic respiration or ferments, ex. Escherichia coli, Staphylococcus aureus
Microaerophillic – Requires oxygen but at lower than atmospheric levels, ex. Streptococcus sp. Campylobacter sp.
Aerotolerant anaerobes – do not use oxygen, ex. Lactobacillus acidophillus
What is triplet oxygen? What are the toxic forms of oxygen?
Triplet Oxygen is Normal oxygen
Toxic forms of oxygen: Singlet Oxygen - 1O2, Peroxide – H2O2, Superoxide – O2-, Hydroxyl radical – OH.
What enzymes destroy toxic oxygen?
Catalase- 2H2O2 2H2O + O2
Peroxidase - H2O2 + NADH+ H+ 2H2O +NAD
Superoxide dismutase - 2O2- + 2H+ 2H2O2 + O2
Superoxide reductase - O2- + 2H+ + cyt cred H2O2 + cyt cox
What are capnophiles?
organisms that grow best at a higher CO2 tension than is normally present in the atmosphere and are Important in the initial isolation of the following organisms from clinical specimens:
- Neisseria (gonorrhea, meningitis)
- Brucella (undulant fever)
- Streptococcus pneumoniae
What are barophiles?
Existunderpressuresthatrangefroma few times to over 1,000 times the pressure of the atmosphere and These bacteria are so strictly adapted to high pressures that they will rupture when exposed to normal atmospheric pressure.
