Where do microbes get their energy from?
light or food
What is the carbon source for autotrobes?
out of the air
Psychrophiles
grow in low temps
Mesophiles
grow at human body temp
Thermophiles
grow in hot temps
pH of acidophiles
very low, <5 (listeria, mold)
pH of yeasts and molds
usually 5-6, moderately acidic
pH of most bacteria
6-9, neutral
What do fermenters produce?
acid
H. Pylori
gram negative rod, grows in the stomach (embeds in the mucosa), forms biofilms. Cleaves urea (finds) and produces CO2 and NH3. Most ulcer are caused by this. Lives in pH 5. Ammonia is the base, CO2 is a weak acid. Lochotricheas
Osmotic pressure
depends on saltiness, sugary environment. Halophiles.
Carbon sources
50% of dry weight of living material. Autotrophs take out of the air (CO2), Heterotrophs eat organic material
Nitrogen sources
14% of dry weight, needs N. Sources are Nitrogen fixation, NH4, NO3, Protein digestion (eat, takes N from food)
Sulfur sources
amino acids, vitamins. H2S, SO4
Phosphorus sources
nucleic acids, phospholipids. PO4, from environment (rocks). Often limiting in nature. Algae blooms= phosphorus release. Sweating also releases phosphorus. Agricultural run-off in the summer from fertilizer that was put down in the soil, runs off to river
Oxygen testing
Uses thioglycolate broth (semisolid). Determines the o2 requirement. 1. Obligate aerobe (most o2 at top). 2. Obligate anaerobe. 3. Facultative anaerobe (bit thicker at top 1/2, growth t/o. Can use o2 but doesn't require). 4. Micoraerophile (little o2) 5.
Oxygen toxicity
Superoxide is very reactive, toxic. Ionic. Peroxide is detox by peroxidase and catalase. Hydroxyl radical is very reactive
Catalase test
o2 makes bubbles. Mix H2O2 and cx. Bubbles are positive
Handling and safety, biosafety level
1- Safest. 4- most dangerous
Defined media
precise chemical composition. No complex organics. Typically used for lab studies. Chemautotrophs most commonly used.
Complex media
very common in medical settings. Variable composition. Protein. Yeast, meat extracts. Salt or boil to kill, take solids from yeast
Enriched media
used for something extra, great. For hard to grow organisms (fastidious). Chocolate agar, Thayer-Martin (for gonorrhea)
Selective media
allows some growth, inhibits others. Slow growers
Sabourad's Dextrose Agar
selective media, for yeast and mold, d/t pH
PEA
selective, gram positives, toxic to gram negatives- ETOH d/t membrane dissolving. Gram + not affected d/t thick peptidoglycan walls
Differential media
tells you about bacteria by the way it looks. Determines identify. Uses substrate, detects end product
Mannitol Salt Agar
selective and differential. Skin microbes, staph. High salt inhibits most bacteria. Staph ferments to mannitol
Blood agar
sheep blood. Hemolysis, blood breaking. Alpha (partial RBC destruction), beta (complete RBC destruction), gamma (absence of hemolysis)
Bile-Esculin Agar
Selective and differential. Enterococcus, streptococcus= can tell these apart. Bile salts are toxic to cells, except intestinal cells
MacConkey's Agar
tells intestinal pathogens. Selective and differential Ferments lactose, indicator is pink. Does not ferment lactose, indicator colorless. Crystal violet is toxic to gram +
Anaerobic cultures
control the inner atmosphere. Uses reducing media, anaerobic jars. Controls the inner atmosphere, rids o2 from chambers
Special cultures
used for CA cells, easy to grow cells.
Campylobacter
bent, spiral rods. Gram negative. Common cause of food poisoning. Must have the right amount of o2.
Isolation
streak method. Dilution method. Isolates organism, take inoculating loop and heat to sterilize. Get dime sized specimen on plate, sterilize loop again and streak x 4. Sterilize again, then go through streaks again x 4. Cover as much area as possible. Will
Preservation
bacteria you want to keep. Regrow before they die. Deep freezing and freeze-drying (pulls off moisture)
Biofilms
produces chemical signal, if only one there won't be much. If several (surrounded by it's own kind), there will be several made. They lyse themselves. Determined by how much of a chemical signal is sent and received.
Cell division
Binary fission, budding (asym. division), Mitosis (eukaryotes), generation time (time from one replication to the next).
Growth phases
Lag (couple hours to acclimate themselves to new environment.)
Log (exponential, reach full potential, q 25 minutes)
Stationary: overcrowded, runs out of food
Death
Counting bacteria
Direct counts: Worst way. counting chamber, obvious
Turbidity: cloudiness, shine light through
Weight
Plate counts: best way to count living, counted in CFU's
Plate count
plate of 2 live bacteria will multiply too much. Track down to a manageable number (20-200), 10 fold dilution