Microbiology
The study of organisms too small to be seen without magnification. –Bacteria –Viruses –Fungi –Protozoa –Helminths (worms) –algae
Branches of study within microbiology Immunology Public health microbiology & epidemiology Food, dairy and aquatic microbiology Biotechnology Genetic engineering & recombinant DNA technology
Microbes are involved in Nutrient production & energy flow Decomposition Production of foods, drugs & vaccines Bioremediation Causing disease
Impact of pathogens Nearly 2,000 different microbes cause diseases. 10 billion infections/year worldwide. 13 million deaths from infections/year worldwide.
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.
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
Bacteria
Binary Fission Reproduction One cell grows to about double its original size and then splits. –Dna replicates –divides
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
diplococcus
streptococcus
Tetrad
sarcina
staphylococcus
Bacillus Rod-shaped bacteria
Bacillus
Bacillus under scanning electron microscope
Escherichia coli
Spiral 3 forms: vibrio, spirillum, spirochete
Vibrio cholerae
Spirillum
Spirochete
Identifying Bacteria Gram Positive Gram Negative Shape
Gram-Positive After being stained appears purple. Due to a peptidoglycan wall. Thicker wall
Gram-negative Appears red when gram stained. Picks up safranin stain. Thin wall.
How they use oxygen? Facultative anaerobe - Prefer to grow in the presence of oxygen, but can grow in an anaerobic environment using fermentation.
Strict Aerobe Cannot survive in the absence of oxygen.
Strict Anaerobe Generate energy by fermentation and are killed in the presence of oxygen.
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.
Autoclave Pressurized device designed to elevate temperature and pressure to sterilize material and solutions.
Media Liquid media Semi-solid media Solid media
Semi-solid media Can be used for motility testing.
Solid Media Contains more agar = where microbes grow. This enables the formation of colonies.
Different Media Grows all: Some agar grows everything. Differential media: Some shows different reactions. Selective media: Some can grow certain bacteria.
MacConkey Agar Differential media. Detects lactose fermentation.
Viewing Microbes Resolution(seeing detail) can be increased using immersion oil. Allows the light ray to go directly through the objective lens.
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