MIC 205 1st Edition Lecture 10 Outline of Last Lecture I. Microbial GrowthII. Nutritional Requirementsa. Energyb. Carbonc. OxygenOutline of Current Lecture III. Physical Requirements for Growth (Environmental)IV. Microbial ControlV. Microbial DeathCurrent Lecture Physical (Environmental) Requirements for growth- Temperatureo Most microbs have maximal growth at a specific optimum tempterature o Psychrophiles, mesophiles, thermophiles, hyperthermophiles- pHo hydrogen ion concentrationo buffers resist pH changeo most bacteria/protozoa like neutral pH (6.5-7.5) –neutrophileso some bacteria/fungi like acidic—acidophileso alkaline (basic) soils/water environments—alkalinophiles (up to pH 11.5)- Water-physical effectso Microbs need water to dissolve enzymeso Restricts organisms to certain environments Obligate halophiles-require salt, up to 30% Facultative halophiles- can tolerate high salt concentrations but don’t require Barophiles- organisms that live under extreme pressureMicrobial Control-in the environment (not humans)- Sterilization- completely gets rid of all microbes- Aseptic-working in a lab/healthcare setting with the absence of microbesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Disinfection/disinfectants-removes most of the microbes (NOT all) using chemicals- Antisepsis/antiseptic-disinfection of human surfaces- Degerming-physical disinfection by scrubbing, rubbing- Sanitization- disinfection of public surfaces- Pasteurization- disinfection of foods/drinks with mild heatSuffixes: - Stasis/static- controls growth- Cide/cidal- kills, “suicide”Microbial Death-rate of population dying is constant *faster sterility = fewer organismsSusceptibility of Microorganisms- Most resistant-Least resistanto Prions, bacterial endospores, mycobacteria, cysts of protozoa, active stage protozoa, gram-negative, fungi, nonenveloped viruses, gram-positive, enveloped virusesAntimicrobial agents (how killing is achieved) - Alteration of cell wall/membrane- Interference with protein/nucleic acid structure Diffusion Susceptibility Tests-Kirby-Bauer Method- Zone of inhibition- no microbes grew here- Method is used to test the effectiveness of antimicrobial agents on specific
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