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57 Cards in this Set
- Front
- Back
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Classify microbes into 5 groups on the basis of preferred temperature range
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Psychrophiles, Psychrotrophs, Mesophiles, Thermophiles, and Hyperthermophiles
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Identify how and why the pH of culture media is controlled...
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They often produce acids that interfere with their own growth when cultured, so chemical buffers are included to neutralize and maintain proper pH
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Importance of osmotic pressure to microbial growth?
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used to preserve foods and prevent the growth of microbes
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name a use for each of the four elements (carbon, nitrogen, sulfur, and phosphorus) needed in large amounts for microbial growth.
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carbon; structural backbone
nitrogen; synthesizes protein and helps DNA and RNA synthesize sulfur; synthesizes sulfur-containing amino acids and vitamins phosphorus; synthesizes nucleic acids and phospholipids of cell membranes |
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define nitrogen fixation
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use of gaseous nitrogen (N2) directly from atmosphere to synthesize
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Explain how microbes are classified on the basis of oxygen requirements.
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Require oxygen to live: Obligate aerobes
Ability to grow in absence of oxygen: Facultative anaerobes Can not live where oxygen is present: Obligate anaerobes Can not use oxygen to grow but they tolerate it: Aerotolerant anaerobes Require oxygen but only grow in low concentrations: Microaerophiles |
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Identify ways in which aerobes avoid damage by toxic forms of oxygen,
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- develop enzymes to neutralize it such as catalase which converts in to water.
-singlet oxygen is normal oxygen (o2) that has been boosted into a higher-energy state |
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Aerobe vs Anaerobe
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aerobe requires molecular oxygen for growth and an anaerobe does not.
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Describe the formation of biofilms and their potential for causing infection.
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pillar like structures of slime with channels through water can carry incoming nutrients and outgoing waste.
-can be formed by fungi which are encountered in many disease conditions |
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chemically defined vs complex media.
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Chemically defined medium is one whose exact chemical composition is known. Complex medium varies from batch to batch
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What bacteria physically require:
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temp, pH, osmotic pressure, atmospheric pressure
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food preservative
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psychotrophs
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Hydrogen ion concentration & ph
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10^0 ---- 10^ -7 ------10^ -14
0---------7---------14pH |
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pH=?
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pH= -log[H+]
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ph is a.... of the .... in....
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pH is a MEAURE of the HYDROGEN in CONCENTRATION
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the pH scale
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0-7=acidic
7=neutral 7-14=alkaline |
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Fermentation by Microbes end products
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a lot of acidic and toxic products
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lactobacillus acidophilus
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-lactic acid producers
-aerotolerant anaerobe -use it industrially in probiotics -found in oral cavity, small intestine, and vag -beneficial |
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osmotic pressure: isotonic solution vs. hypertonic solution
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isotonic: solute concentration in cell is = to solute concentration of .85% NaCl (sodium chloride)
hypertonic: if concentration of solutes such as NaCl is higher in surrounding medium than in cell, water leaves cell and cell can not grow |
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Pseudomonas aeruginosa Biofilm
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-lot of enzymes enabling it to have many potential hosts
-releases blue pigment when in a colony |
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Advantages of Biofilm
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-doesn't dry out
-shares nutrients -waste removal -avoids host immune system -resistant to antibiotics -resistant to microbicides -communication and group action -shelter from environmental factors -shares genetic material, conjugation -works together on complex tasks(cow digestion) -soil structure* |
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Quorum-sensing:
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-Bonnie Bassler
-bacteria communicate with chemical signals -used to identify whether or not they have enough bacteria -lock and key mechanism |
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chemoheterotroph:
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chemo (organic molecules for carbon)
hetero (eats, uses chemical source for energy) troph (for nutrition) -source of carbon, supple oxygen, and nutrients. |
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chemically complex medium:
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-nutrients are in agar
-growth of heterotrophic bacteria -"beef extract" and peptone (partially digested protein) |
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anaerobic bacteria culture:
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-has to be in container
-needs armadillos to grow |
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Biocontainment: 4 levels
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1) moderate precautions (goggles, gloves, aprons)
2)PPE 3) air circulation 4) sealed environment w/ negative atmospheric pressure (TB rooms) |
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Blood agars:
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-50% sheep blood
-differential -beta-hemolysis (break down of blood cells) |
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Mannitol Salt Agar
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-both selective and differential
-S. auerus is halotolerant -nutrition source to allow things to grow |
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Binary Fission:
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2 cells become 4 > 8 >16 >32
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phylum proteobacteria:
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-gram - and chemoheterotrophic bacteria
-based on rRNA |
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alphaproteobacteria
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-capable of growth at low levels of nutrition
-pathogens -some agriculturally important |
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betaproteobacteria
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-some use less common nutrient substances
-some are pathogenic |
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gammaproteobacteria
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-diverse, includes e.coli
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deltaproteobacteria
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-some predators
-some participate in sulfur cycle |
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phylum cyanobacteria
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gram negative, autotrophic
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phylum firmicutes
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-gram positive, love G+C content
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phylum actinobacteria
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gram positive, high G+C content
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Rhizobia sp.
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-corn takes a lot of nitrogen from soil, rhizobia puts it back in
-takes atmospheric N2 and makes ions NH4 (ammonium) + NO-2 (nitrate) -forms nodules on roots -enters through root hair -Proteobacteria (phylum) Alpha (class) |
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Agrobacteria sp.
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-crown gall (plant tumor)
-plasmids are vectors -gram - -Proteobacteria (phylum) Alpha (class) |
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Neisseria sp.( 8 )
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-responsible for gonorrhea
-exists as a diploid (mid division) -fimbriae allow it to stick to things -cross species -Proteobacteria (phylum) Beta (class) |
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Pseudomonas sp. (sperm looking)
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-opportunistic infection
-array of enzymes therefore can exist in many environments -motile --Proteobacteria (phylum) Gamma (class) |
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Enterobacteriales (Order)
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-ex: e.coli, salmonella, e. aerogenes
-coli form -evdidence of fecal contamination -Proteobacteria (phylum) Gamma (class) |
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Cyanobacteria (Phylum)
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-gram negative
-photosynthesizing -nitrogen-fixing -"moving algae" |
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Filamentous
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-gram negative
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Bacillus sp.
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-gram positive, low G+C***
-strain called "BT Kurstaki" -kills caterpillars -Israeliensis- kills mosquittos -BT genes- toxic crystal gene -GMO- genetically modified -Firmicutes (phylum) |
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Staphylococcus sp.
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-adapt and have resistant strains quickly
-s. epidermidis, s. aureus -Firmicutes (phylum) |
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Streptococcus sp.
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-Rebecca Lancefield
-obligate anaerobes but aerotolerate -only ferment -Firmicutes (phylum) |
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lactobacillus sp.
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-lactobacillus acidophilus -> "good" intestinal microbe
-lactic acid producing bacteria -aerotolerant -inhibits growth of other organisms, allowing them to grow despite metabolism -Firmicutes (phylum) |
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Enterococcus sp.
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-nosocomial
-likes regions high in nutrients (intestinal tract, vag, oral cavity) -Firmicute (phylum) |
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Mycoplasma sp.
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-bacteria with no cell wall
-extremely small -smallest self-replicating unicellular organism -Firmicutes (phylum |
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Mycobacterium sp.
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-needs acid fast stain
-wax coating -gram negative -Actinobacteria (phylum) |
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Streptomyces sp.
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-filamentous
-coils -Actinobacteria (phylum) |
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Pyrodictium abyssi
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-from deep sea vents
-Archaea (domain) |
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Coliform:
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-aerobic or facultative anaerobic, gram negative, non-endospore forming, rod-shaped bacteria that ferment lactose with acid and gas within 48 hours at 35 degrees Celsius
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diplococcus
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cocci that divide and remain attached in pairs
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enteric
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common name for bacterium in the family of enterobacteriaceae.
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serovar/serotyoe
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variation within a species
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