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56 Cards in this Set
- Front
- Back
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Bacteria Growth Measurements |
spectrophotometer, coulter count, petroff hausser counting chamber, membrane filtration method, turbidity |
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Specrtophotometer |
the amount of light that passes through the sample is measured using a detector disadvantage: cannot discriminate b/w live and dead cells |
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Coulter Counter |
electrically counts cells as they pass through device disadvantage: cannot discriminate live and dead cells |
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Petroff Hausser Counting Chamber |
manual cell count with a microscope disadvantage: cannot discriminate b/w live and dead cells; not possible to give a number for viable cells |
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Membrane Filtration Method |
sample is passed through a filter that traps cells; the filter is then placed on a agar surface that allows development of colonies a count of visible colonies on the membrane surface gives the number of viable microorganisms |
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Spread and Pour Plate Methods |
a count of visible colonies gives the number of viable microorganisms |
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Bacterial Growth |
increase in number of cells can either be measured quantitatively (quantity) or qualitatively (type of organism) through binary fission |
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Generation Time |
the time it takes for the population to double genetically determined Salmonella enteritidis and Staphylococcus aureus- double in 30 minutes Mycobacterium leprae – double in 10-30 days |
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Stages In Normal Growth Curve |
lag phase, log phase, stationary phase, death/decline phase |
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Lag Phase |
cells are metabolically active not reproducing yet |
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Log Phase |
cells are reproducing at exponential rate |
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Stationary Phase |
rate of cell reproduction is equal to the rate of cells dying |
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Death Phase |
cells dying off at exponential rate |
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Obligate Aerobe |
an organism that cannot grow without oxygen can only grow in the top of the tube growth at top surface of agar |
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Facultative Anaerobe |
does not require oxygen for its metabolism and is capable of growth in the absence of it can grow in both aerobic and anaerobic conditions growth throughout agar and on top |
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Microaerophile |
does not grow at normal atmospheric concentrations of oxygen but requires a small amount of it (1-15%) heaviest growth on band just below surface of agar |
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Strict or Obligate Anaerobes |
lack enzymes for processing toxic oxygen they cannot tolerate any free oxygen they do not use oxygen for respiration and are not able to grow in the presence of oxygen growth at the bottom of tube |
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Aerotolerant Anaerobes |
do not utilize oxygen but can survive and grow in its presence no growth or growth below surface of agar but not on it |
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Capnophile |
grow best at higher CO2 tensions (3%-10%) |
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GasPak Jars, Specialized Media (Thioglycolate), Anaerobic Environment Chamber |
methods to allow anaerobic and capnophilic growth |
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Thioglycolate Broth |
a reducing media helps determine oxygen requirements of isolates allows the growth of anaerobic bacteria its acid slows the penetration of oxygen reducing its availability allows all organisms to grow |
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Thioglycollate Tubes |
for measuring oxygen requirements creates a reduced environment in this semi-soft agar, with a small amount of oxygen diffusing in from the top organisms with different oxygen requirements will grow in different parts of the tube |
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Colony Characteristics |
shape: circluar, rhizoid, irregular, filamentous, spindle margin: entire, undulate, lobate, curled, rhizoid, filamentous elevation: flat, raised, convex, pulvinate, umbonate size: puntiform, small, moderate, large texture: smooth, rough appearance: glistening, dull pigmentation: nonpigmented- (cream, tan), pigmented- (purple, red, yellow) optical property: opaque, translucent, transparent |
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Growth Patterns on Slant |
filiform (thread-like), arborescent (tree-like), beaded, effuse (spreading), rhizoid, echinulate (spiny) |
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Cultural Characteristics in Broth |
clear (no growth), turbid (cloudy), flocculent, pellicle, sediment |
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Cellular Morphology (Bacterial Shapes & Arrangements) |
bacillus, coccus, spirillum, spirochete, vibrio, streptococcus, staphylococcus, diplococcus, streptobacillus, palisading- side by side |
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Autotrophs |
self feeding an organism that utilizes inorganic carbon as their source of carbon include: cyanobacteria- use CO2 in the presence of photosynthesis to synthesize their own carbohydrates |
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Heterotrophs |
feed off others organisms that cannot synthesize organic molecules from CO2 must use preformed organic molecules in their environment as carbon source most bacteria are this |
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Fastidious |
an organism that requires a variety of growth factors and nutrients from the environment and will not grow well if these factors are not present |
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Special Media |
used to cultivate bacteria in the lab to create a proper environment |
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Complex Medium |
uses preparations of extracts from other organisms extracts are not chemically defined extracts obtained from animals, plants, or yeast commonly used: yeast extract agar, brain-heart infusion agar milk and peptone can also be used |
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Chemically Defined Medium |
contain pure organic or inorganic compounds added in finite amounts defined medium- used for narrow range of bacteria that are less fastidious |
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Enriched Medium |
media to which specific nutrients are added to support the growth of fastidious organisms ex. blood agar used to grow Streptococcus |
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Blood Agar |
an enriched medium contains blood which provides necessary nutrients like iron and protein to support the growth of very fastidious Streptococci |
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Chocolate Agar |
heated blood agar |
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Absorbance |
a spectrophotometric measurement measures amount of light absorbed or dispersed by the specimen directly proportional to cell number the more cells present the higher the absorbance |
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Transmittance |
a spectrophotometric measurement measures how much light passes through the sample high values indicate that more light is passing through sample inversely proportional to cell number |
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Fermentation |
organic molecules like pyruvate and pyruvate deratives act as the final electron acceptors allowing glycolysis to continue in the absence of oxygen |
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Gas Gangrene |
a dangerous infection of deeper tissues also known as clostridial myonecrosis cause by anaerobe Clostridium perfringens tissue death and swelling by gas in tissues |
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Brain-Heart Infusion Agar |
an enriched medium for the cultivation of fastidious microorganism |
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Hydrogen Peroxide |
a harmful by-product where bacterial cells carry out different metabolic pathways (aerobic metabolism) produced by the electron transport chain during the reduction (gain) of oxygen a reactive oxygen species toxic to cells |
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Oxidases |
enzymes of the electron transport chain reduces oxygen to form, among other products, hydrogen peroxide |
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Reactive Oxygen Species |
can cause significant damage to important molecules of bacterium like DNA, RNA, and proteins include: H2O2 |
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Catalase |
produced by bacteria to detoxify ROS converts H2O2 into H2O and O2 gas which are harmless to cell allows bacterium to survive and thrive in oxygen-rich environments bubbling will appear if organism produces this due to production of O2 gas from breakdown of H2O2- organism is catalase-positive used to determine gram-positive cocci from one another catalase-positive include: Staphylococcus- difficult to treat and Micrococcus catalase-negative include: Enteroccocus and Streptococcus- difficult to treat 2H2O2> 2H2O + O2 |
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Enterococcus |
catalase-negative hospital acquired requires newer antibiotics or combinations of antibiotics natural resistance to penicillin, multiple antibiotics, cephalosporins, sulfamethoxazole |
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Catalase-Positive |
bubbling include: Staphylococcus- difficult to treat, Micrococcus |
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Catalase-Negative |
no bubbling include: Enteroccocus, Streptococcus- difficult to treat |
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Oxidase Test |
used to differentiate gram negative bacilli used to identify bacteria that use the enzyme cytochrome c oxidase for cellular respiration include: difco slide test, swab test using oxidase reagent |
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Cytochrome C Oxidase |
the final enzyme used in the electron transport chain |
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Chromogenic Reducing Agent |
chemical that develops color as it is oxidized |
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Tetramethyl-P-Phenylenediamine |
the reagent used to test for the enzyme cytochrome c oxidase |
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Oxidase Agent |
colorless in reduced state and turns purple when oxidized |
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Oxidase Positive |
Neisseria, Pseudomonadaceae |
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Oxidase Negative |
Enterobacteriaceae |
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Catalase and Oxidase Test |
used to differentiate bacterial groups |
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Catalase Test |
used to differentiate catalase positive organisms from catalase negative organisms used to differentiate gram positive cocci |
