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Antiseptics
Three Examples:
Antisepetics are microbe- killing chemicals applied to live tissue
Example... hydrogen peroxide, rubbing alcohol , and iodine
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Antibiotics
Three Examples:
Antibiotics are micro-killing chemical taken internally [pill/ liquid form]
Example... Penicillin, Ampicillin, Streptomycin, and Chloramphenicol
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Disinfectants
Applied to inert surfaces
Includes Chlorine bleach and Lysol
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Disk- Diffusion Test
or
Kirby-Bauer Method
The effectiveness of these substances in killing microbes
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Zone of Inhibition
The clear zone that appear around the disk.
Large the zone of inhibition the better the chemical.
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Soil Microflora
Astounding diversity and number of microbes, predominantly bacterica and fungi.
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Fixed Nitrogen
Nitrogen gas that plants can utilize.
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Nitrogen Fixation
Nitrogen gas that has been converted by soil microbes to other compounds microbiological result
Example ammonia, ammonium ion and nitrate ion
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Symbiotic Nitrogen- fixing bacterica
Legume plants
Live inside the roots of legume plants
Legume plants... clovers, beans, peas, peanuts and soybeans.
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Rhizobium Leguminosarum
Gram-negative bacterica bind to root hair of young legume plant and cause plant to develop root nodule
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Root Nodule
Rhizobium fixes nitrogen gas into ammonia, which plant uses for nutrition
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Nutrient Agar (NA)
1ml or 0.1ml has more microbes
Allows both bacteria and fungi to grow
NA 1ml has more microbes b/c 0.1ml less dilute
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Czapek- Dox Agar (CD)
Discourages bacteria but encourages fungi to grow
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Dilution Equation
volume of sample / (volume of sample + volume of diluent)
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Pour Plate Technique
- Prepare the Nutrient Agar and Czapek-Dox Agar plates.
- 1ml of 10-4 or 10-2 soil dilution then melted NA / CD
- 0.1ml of 10-4 or 10-2 soil dilution then melted NA/ CD
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Plate Count
number of bacteria colonies and fungi colonies (fuzzy growth)
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Actinomycetes
Fungus-like filamentous soil bacterica
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Brown Diffusate
Brown zone around the colony in surrounding agar.
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Colony- Forming Units
CFU/g soil sample = (# colonies on plate) * (1/ volume of sample) * (1/dilution)
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Ammonification
Production of ammonia from nitrogenous compounds such as casein and peptone
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No ammonia or small amount of ammonia
Moderate amount of ammonia
Large amount of ammonia
faint yellow
deep yellow to orange
brown
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.1
.01
.001
1/10 10-1
1/100 10-2
1/1000 10-3
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Subkingdom Protozoa
Unicellular, eukaryotic microbes in the Kingdom Protista.
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Pathogenic
Cause diseases in humans
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Presumptive Test
Detect coliform bacteria in a water sample
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Confirmed Test
follows a positive Presumptive Test, to ensure bacterial contamination due to coliforms.
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Brilliant Green Bile Broth (BGBB)
- used in Confirmed Test
- selective medium that must indicate Gram- negative bacteria
- differential medium contain lactose
- gas bubble produced when coliform are grown (positive Confirmed Test)
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Completed Test
final analysis of water sample using EMB and MAC
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Eosin Methylene Blue Agar (EMB) AND MacConkey Agar (MAC)
- selective media that grow Gram-negative bacteria
- differential media change colors when certain types of bacteria grown on them
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When coliform grown on EMB agar
colonies have dark centers and green metallic sheen
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When coliform grown on MAC agar
colonies will be pink/red and pink diffusate visible around the colonies
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Contagious
easily passed from host to host
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Communicable
diseases passed from host to host
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Epidemic
one of the worst bacterial diseases of all time cause by bacterium Yersinia Petstis
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