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45 Cards in this Set
- Front
- Back
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Why do we need to know how the microbes grow?
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because in order to understand and solve a problem we need to know the cause
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Who is a historical figure in growing microbes?
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Robert Koch
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What became possible because of Robert Koch's breakthrough, earning his a Nobel Prize in 1905?
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isolation/identification of bacteria
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Why is preservation of bacteria important?
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it allows scientist to access reference organisms at wish
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What is the preferred method of preservation?
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Lyophilization or the removal of water and further freezing
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What are biofilms?
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bacteria in nature coming together
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What gives films the slimy appearance?
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extracellular polymeric substances (EPS)
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What are the requirements for successful growth?
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1. Sterile environment: without bacteria
2. Aseptic technique: prevents contamination |
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How do microbes grow?
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1. They use a process called binary fission
2. at the time, determined by who the microbe is and based on proper conditions, the microbe doubles its content and slits into two identical cells |
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What do we grow bacteria in?
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Media
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What can media be?
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1. Liquid: broth, tubes, no agar
2. Solid: plates or tubes 3. Semisolid: some agar but medium is not hard, allows detection of motility |
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What are the isolation techniques?
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1. streak plate technique
2. spread plate technique 3. pour plate technique |
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How does the streak plate technique work?
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inoculation loop used to streak the surface of an agar plate; each streak carrying less organisms than the one before
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How does the spread plate technique work?
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using a glass stick to disperse the sample placed on the surface of the agar
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How does the pour plate technique work?
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diluting the sample as needed and pouring an aliquot into the plate; suitable for counting
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How do you maintain stocks?
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1. successive passages to new media and kept at refrigerator temperatures
2. freezing at -70 C in a solution containing glycerol |
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What is the growth curve?
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in the lab, batch cultures grow following the stages in the growth curve. To keep continuous growth the system must be open
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What are the effects of environmental factors in bacterial growth?
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1. Temperature
2. pH 3. salt content 4. presence or absence of oxygen and pressure |
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What are the different categories of pH?
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1. acidophiles
2. neutrophiles 3. alkalophiles |
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What is the range for acidophiles best growth?
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less than pH 5.5
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What is the range for neutrophiles best growth?
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between 5 and 8 with optimal at 7
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What is the range for alkalophiles best growth?
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above 8.5
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What is an obligate aerober?
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dead in absense of oxygen
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What is an obligate anaerobe?
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dead in the presence of oxygen
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What is an facultative anaerobe?
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better if oxygen is present but can survive without it
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What is an aerotolerant anaerobe?
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indifferent to oxygen. They are fermenters
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What is microaerophile?
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small amount of oxygen needed
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What is halotolerant (osmotolerant)?
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tolerate high salt up to 10% NaCl
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What is halophile?
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need high salt to grow(9%); Dead Sea
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What is barophilic?
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can tolerate high pressure (1atm; 760 mmHg; very distint and strange; live in the ocean)
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What are needed elements for growth?
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C, N, S, P, O, H
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What are trace elements for growth?
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Cu, Zn, Fe, Co, Na, Cl, K, Mg, Mn
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What are cofactors for growth?
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vitamins
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What are energy sources for growth?
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1. Light = phototrophs
2. Chemical compounds = chemotrophs 3. Autotrophs = make their own food 4. Heterotrophs = feed on others |
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What are characteristics of Complex Media?
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1. common use
2. variety of ingredient: peptone, extracts, sugar 3. Blood agar, chocolate sugar |
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What are characteristics of Defined Media?
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1. Research use
2. Precise amounts of pure chemicals 3. Glucose salts |
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What are characteristics of Selective Media?
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1. inhibits the growth of some microbes
2. Thayer Martin, McConkey, Mannitol Salt Agar |
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What are characteristics of Differential Media?
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1. Contains a substance that changes allowing recognition of a particular microbe
2. McConkey, Blood agar, Eosine Methylene Blue, MSA |
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What are characteristics of Enrichment Media?
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1. Provides conditions that enhance the growth of one species in a mixed population
2. Selenite broth is an example |
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What are the ways to measure bacterial growth?
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1. direct counting using chambered slides
2. cell mass using a turbidimetric device 3.filter-counting 4. MPN = most probable number 5. Detect cell product like acid, gas, or ATP |
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What is the problem with direct counting using chamber slides?
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it does not distinguish between dead and alive
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What is the problem with cell mass using a turbidimetric device?
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it needs at least a million cells to be useful
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What is filter-counting mostly for?
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water and air
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What is MPN used for?
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strictly mathematical prediction; used for water analysis
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Who is the best?
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Sarah
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