BIO205 - Ch 6 - Microbial Growth - RioSalado - AZ
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| Groups of cells large enough to see without microscope. | Colonies - hundreds of thousands of cells
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| 2 main requirements for microbial growth. | Physical (temp, pH, osmotic pressure), & chemical (carbon, nitrogen, oxygen, phosphorus, etc.)
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| 3 temperature classifications of microbes. | (1) psychrophiles (cold-loving), (2) mesophiles (moderate-temp-loving), & (3) thermophiles (heat-loving).
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| Why is it difficult to define psychrophile, mesophile, & thermophile? | Because their ranges & max. growth temps that define them "are not rigidly defined."
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| Which group of bacteria grow well in refrigerator temperature? | Psychrotrophs - "moderate or faculative".
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| Many thermophilic bacteria cannot grow below __ degree Celsius. | 45
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| Extreme hyperthermophiles have optimum growth temp. of __ degree Celsius. | 80+
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| Acidophiles can tolerate? | acidity - low pH of 1 even
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| Optimum pH of molds & yeast | 5-6 pH
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| Osmotic loss of water causes __. | plasmolysis
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| Obligate/extreme halophiles | high salt concentrations - lovers
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| Chemoautotrops & photoautotrops get carbon how? | from CO2
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| Besides carbon, DNA & RNA synthesis require? | nitrogen & phosphorus
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| Half the dry weight of bacterial cell is? | carbon
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| Organisms use nitrogen primarily to form __. | amino group of the amino acids of proteins.
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| Name 3 foods preserved by high osmotic pressure. | salted fish, honey, sweetened condensed milk
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| nitrogen fixation | Using gaseous nitrogen directly from atmosphere (N2)
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| How is sulfur used? | to synthesize sulfer - containing amino acids & vitamins like thiamine & biotin
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| phosphorus is essential for? | Synthesis of nucleic acids & phospholipids of cell membrane, & ATP
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| Potassium, magnesium, & calcium used as __. | cofactors for enzymes
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| Name some trace elements | iron, copper, molybdenum, & zinc - usually cofactors
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| Which bacteria are primary producers at ocean floor? | chemoautotrophs
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| Organisms that require oxygen to live. | obligate aerobes
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| Faculative anaerobes use what? | Oxygen when available but cause use fermentation to continue growth - like E. coli
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| Bacteria unable to use molecular oxygen | Obligate anaerobes - like tetanus & botulism
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| SOD - super oxide dismutase | an enzyme that destroys super oxide (O2) free radicals.
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| Super oxide free radical | A toxic form of oxygen (O2-) formed during aerobic respiration.
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| Singlet oxygen | Highly reactive molecular oxygen (CO2-)
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| Which bacteria lack SOD? | Obligate anaerobes - lack this enzyme to nutralize oxygen.
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| peroxide anion | O2^2- - toxic - part of hydrogen peroxide & benzoyl peroxide - catalase nutralizes.
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| peroxidase | breaks down hydrogen peroxide
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| hydroxyl radical (OH) | Most reactive oxygen form - produced in aerobic respiration
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| Microaerophiles | Aerobic bacteria that grow only in low oxygen concentrations.
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| Organic growth factors | Essential organic compounds an organism cannot synthesize on own & must obtain from environment. Ex - humans needing vitamins.
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| Culture medium | Nutrient material prepared fro growth of microorganism in lab.
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| Inoculum | Microbes introduced to culture medium to initiate growth.
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| culture | microbes that grow & multiply in or on a culture medium.
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| agar | solidifying agent made of a complex polysaccharide derived from marine alga - thickens jellies & ice cream - hard for bacteria to degrade.
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| Chemically defined medium | culture medium with exactly known chemical composition
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| complex media | culture medium with varying chemical composition.
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| nutrient broth | complex medium in liquid form
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| nutrient agar | complex medium in solid form
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| reducing media | Culture medium that removes dissolved oxygen to allow anaerobes to grow - special anaerobic jars, etc. are used.
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| oxyrase | respiratory enzyme used to remove oxygen from petri plates.
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| High CO2 levels are obtained with __ jars. | candle - lighted candle consumes oxygen.
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| capnophiles | microbes that grow better at high CO2 concentrations
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| selective media | suppress growth of unwanted bacteria & encourage growth of desired microbes.
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| defferential media | Solid culture medium used to distinguish colonies of the desired organism grown on same plate as others - Ex: blood agar
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| Enrichment culture | Liquid medium that provides nutrients & environmental conditions favorable to growing specific microbe - selective & used to increase sm. populations.
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| streak plate method is used to obtain? | isloated (pure) culture
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| lypophilization | Freeze-drying - water removed
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| generation time | tme required to double its population
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| What scale is used to graph bacterial growth? | Logarithmic scales
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| Bacterial growth curves show? | Growth of cells over time - lag, log, stationary, & death phase.
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| What occurs during lag phase of growth? | Intense metabolic activity to synthesize reproductive enzymes & molecules.
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| What occurs during log phase of growth? | Period of exponential growth - most active reproductive pahse - most active metabolically - most sensitive to adverse environmental conditions.
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| What occurs during stationary phase of growth? | Growth rate matches death & population stabolizes - metabolic activity slows - equilibrium.
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| What occurs during death phase of growth? | More death than reproduction.
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| Which phase does radiation & antimicrobial drugs interfere with? | Log phase
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| Population numbers are usually recorded as? | cells per milliliter of liquid; or gram of solid material
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| Most frequently used measuring method of bacterial populations. | Plate count - advantage is that it measures number of viable cells, but disadvantage is it takes time.
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| Colony-forming units (CFUs) | Plate counts - colony that results from a chain or bacterial clump instead of just one bacteria.
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| Serial dilutions | Process of diluting a sample several times to make it easier to count.
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| Pour plate method | Method of mixing bacteria into a solid nutrient medium by melting the medium & pouring it into a Petri dish to solidfy.
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| Drawbacks of pour plate method? | Damages heat-senitive microorganisms.
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| Spread plate method | Bacteria added to surface of solid agar medium & spread over the surface with a glass rod.
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| Why is spread plate method better than pour plate? | Bacteria aren't exposed to heat needed to melt medium.
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| Most probable number (MPN) method | Statistical estimation stating that the more bacteria there are, the more dilution needed to produce a zero count.
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| turbidity | How cloudy the medium becomes w/cells - measured by a spectrophotometer - light absorbed by cells.
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