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Microbiology
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The study of organisms too small to be seen without magnification. –Bacteria –Viruses –Fungi –Protozoa –Helminths (worms) –algae
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Branches of study within microbiology Immunology Public health microbiology & epidemiology Food, dairy and aquatic microbiology Biotechnology Genetic engineering & recombinant DNA technology
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Microbes are involved in Nutrient production & energy flow Decomposition Production of foods, drugs & vaccines Bioremediation Causing disease
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Impact of pathogens Nearly 2,000 different microbes cause diseases. 10 billion infections/year worldwide. 13 million deaths from infections/year worldwide.
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Communicable disease – can be spread. Noncommunicable – cannot be spread from one person to another. Black Plague killed 200 million Small pox killed 1/3 of Europe in 1348.
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Reservoirs of Infection Primary habitat in the natural world of a pathogen. Living reservoirs may or may not have symptoms. Vectors – living animal that transmits infectious disease. Nonliving reservoirs – soil, water
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Bacteria
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Binary Fission Reproduction One cell grows to about double its original size and then splits. –Dna replicates –divides
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Shapes of Bacteria Coccus – spherical or oval shaped. -diplococcus: cocci in pairs -streptococcus: cocci in chains -tetrad: arranged in squares of 4 -sarcina: arranged in cubes of 8 -staphylococcus: random planes
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diplococcus
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streptococcus
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Tetrad
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sarcina
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staphylococcus
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Bacillus Rod-shaped bacteria
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Bacillus
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Bacillus under scanning electron microscope
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Escherichia coli
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Spiral 3 forms: vibrio, spirillum, spirochete
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Vibrio cholerae
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Spirillum
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Spirochete
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Identifying Bacteria Gram Positive Gram Negative Shape
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Gram-Positive After being stained appears purple. Due to a peptidoglycan wall. Thicker wall
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Gram-negative Appears red when gram stained. Picks up safranin stain. Thin wall.
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How they use oxygen? Facultative anaerobe - Prefer to grow in the presence of oxygen, but can grow in an anaerobic environment using fermentation.
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Strict Aerobe Cannot survive in the absence of oxygen.
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Strict Anaerobe Generate energy by fermentation and are killed in the presence of oxygen.
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Thioglycollate agar determines the oxygen relationship of a microorganisms. Contains: thioglycollic acid, cystine and 0.35% agar. The thioglycollic acid and agar prevent oxygen from entering the entire medium.
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Autoclave Pressurized device designed to elevate temperature and pressure to sterilize material and solutions.
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Media Liquid media Semi-solid media Solid media
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Semi-solid media Can be used for motility testing.
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Solid Media Contains more agar = where microbes grow. This enables the formation of colonies.
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Different Media Grows all: Some agar grows everything. Differential media: Some shows different reactions. Selective media: Some can grow certain bacteria.
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MacConkey Agar Differential media. Detects lactose fermentation.
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Viewing Microbes Resolution(seeing detail) can be increased using immersion oil. Allows the light ray to go directly through the objective lens.
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Gram Stain Fix microbe onto slide. 20 secs. Crystal Violet Rinse with water 15 secs. Iodine Rinse with water Alcohol rinse 20 secs. Safranin Rinse with water
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