Test Questions on Lab Practical – Flashcards
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| first step of gram stain |
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| add crystal violet |
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| the mordant in the gram stain |
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| Gram's iodine |
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| role of alcohol in gram stain |
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| dissolves lipids in outer membrane and removes the dye from the peptidoglycan layer in GRAM NEGATIVE only |
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| 2nd stain in gram stain |
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| Safranin red |
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| Gram positive cell wall |
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| has thick peptidoglycan wall |
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| gram negative cell wall |
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| has thin peptidoglycan wall |
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| gram positive cells stain |
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| red/pink |
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| gram negative cells stain |
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| violet/purple |
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| examples of gram positive bacteria |
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| Staphylococcus aureus, streptococcus, bacillus |
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| examples of gram negative bacteria |
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| Pseudomonas aeruginosa |
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| example of endospore forming genus |
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| Clostridium |
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| endospore |
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| a survival structure formed within the bacteria wall that allows the cell to survive until the environmental conditions improve |
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| red cells in endospore stain |
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| vegetative cells |
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| green cells in endospore stain |
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| endospores |
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| acid fast cell wall |
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| waxy cell wall of mycolic acid |
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| color of acid fast cells |
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| bright fuchsia pink |
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| color of non acid fast cells |
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| blue--stained with methlyene blue |
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| type of acid fast bacteria |
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| Mycobacteria |
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| Genera of mycobacteria |
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| Mycobacterium, Nocardia TB and leprosy |
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| characteristics of good streak plate |
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| multiple single colonies |
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| halophile |
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| bacteria that can grow in a higher salt concentration than 3% NaCl |
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| psychrophile |
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| organism requiring a temperature of -5C to 15C. only grow below 20 Celsius. |
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| psychrotroph |
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| Live 0°C to 30°C |
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| Mesophile |
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| 15-45 degrees Celsius |
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| Thermophiles |
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| 45-80 degrees Celsius |
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| Extreme thermophiles |
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| 65°C to 110°C |
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| Acidophiles |
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| grow in environments below pH 5.5 |
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| Neutrophiles |
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| live between pH 5.5 & pH 8.5 |
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| Alkilophiles |
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| live above pH 8.5 |
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| Extreme Halophiles |
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| Between 15% to 25% NaCl |
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| Osmotolerant |
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| grow over wide range of salinty |
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| Obligate (strict) aerobes |
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| must have oxygen to carry out metabolism |
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| Microaerophiles |
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| prefer oxygen in concentrations of 2-10% need less oxygen to grow |
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| facultative aerobes (anaerobes) |
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| bacteria that grow well aerobically but can also grow anaerobically if oxygen is not present |
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| Aerotolerant anaerobes |
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| Can tolerate oxygen and can grow but do not require it for energy production. also obligate fermenters because they get their energy strictly by fermentation |
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| Obligate (strict) anaerobes |
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| cannot tolerate oxygen and are killed by its presence |
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| Catalase |
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| An enzyme that degrades hydrogen peroxide into Oxygen and water. |
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| components of fluid thioglycollate medium |
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| A rich liquid medium that supports the growth of both aerobic and anaerobic bacteria. Contains glucose, cystine, and sodium thioglycollate. |
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| the indicator of FTM |
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| reszurin (indicator of the presence of oxygen) turns PINK in the presence of oxygen |
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| Aerobic growth pattern in FTM |
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| only at the top of tube |
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| Microaerophillic growth in FTM |
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| not at the top or bottom--1/3 from the top |
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| facultative growth in FTM |
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| everywhere in the time |
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| anaerobic growth in FTM |
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| only at the bottom |
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| Disinfectants |
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| chemicals that kill microbes on NON-Living Surfaces |
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| Antiseptics |
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| chemicals that are safe on Living surfaces |
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| what type of lab is the disinfectant/antiseptic lab? |
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| chemical control lab |
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| what type of lab is the thermal death time lab? |
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| physical control lab |
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| what is Thermal death time? (TDT) |
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| the length of time at a given temperature that will kill all the cells in a culture |
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| color of MSA (mannitol salt agar plate) |
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| bright pink (slightly opaque) |
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| selective property of MSA plate |
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| contains a high salt concentration (7.5% NaCl) |
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| differential property of MSA plate |
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| contains the sugar mannitol and pH indicator phenol red |
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| color of positive fermentation of MSA plate |
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| yellow |
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| MSA plate is selective for what species? |
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| micrococcus and staphylococcus |
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| selective properties of Eosin methylene Blue plate (EMB) |
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| eosin and methylene blue inhibit growth of gram positive bacteria (only gram negative can grow) |
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| differential properties of EMB plate |
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| contains the sugar lactose which allows differentiation between non lactose fermenters, lactose fermenters, and heavy lactose fermenters |
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| Coliform bacteria |
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| lactose fermenters |
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| color of lactose fermenting bacteria on EMB plate |
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| pink with purple in the center |
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| strong or rapid lactose fermenters color on EMB plate |
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| dark purple with metallic green color |
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| color of non lactose fermenters on EMB plate |
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| colorless (gram negative bacteria only) |
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| color of EMB plate |
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| maroon |
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| what type of growth occurs on Hektoen Enteric Agar? |
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| Selective medium used to isolate gram negative enteric bacteria |
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| selective aspect of Hektoen Enteric agar |
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| bile salts (inhibit the growth of gram positive organisms) |
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| differential aspect of Hektoen enteric agar |
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| lactose, sucrose, and salicin are added to differentiate between non fermenting enteric bacteria and fermentive enteric bacteria |
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| dyes (indicators) added to Hektoen enteric agar |
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| fuschin and bromthymol blue |
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| color of Hektoen agar plate with positive fermentation |
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| yellow to pink color Ex: E. Coli |
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| color of organisms who do NOT ferment any sugars in Hektoen agar plate |
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| blue/green colonies Ex: Salmonella and Shigella |
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| what is added to Hektoen agar to detect for hydrogen sulfide? |
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| Ferric ammonium citrate and sodium thiosulfate--seen as black precipitate Ex: salmonella |
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| indicator in Phenol red broth |
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| Phenol red |
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| tube that collects gases during fermentation |
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| durham tube |
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| color of medium when fermentation is positive in phenol red broth |
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| YELLOW (acid by-products are present) |
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| color of medium if organism CANNOT ferment the sugar is phenol red broth |
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| magenta/fuschia/BRIGHT PINK b/c protein breakdown increases the pH of the medium this is an alkaline reaction |
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| what type of medium is citrate agar? |
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| utilization medium: a defined media in which one or more essential nutrients is limited. |
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| pH indicator of citrate test |
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| bromthymol blue |
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| color of citrate tube when test is positive |
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| if the bacteria can use citrate as its sole source of carbon the tube will change to from green to blue color is green at 6.9 pH and blue at 7.6 pH. |
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| presence of catalase is... |
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| indirect evidence of the ETC |
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| color of M. Luteus growth on Mueller hinton agar |
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| yellow |
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| color of P. aeruginosa on MH agar |
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| green |
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| color of S. marcescens on MH agar |
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| red |
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| what is the purpose of the Phenylalanine Deaminase test? |
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| determines whether or not an organism possesses the enzyme phenylalanine deminase |
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| what is the color indicator of the Phenylalanine Deaminase test? |
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| ferric chloride turns deep green if deamination has taken place |
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| enzyme that can break down starch |
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| amylase |
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| results of a bacteria that produces amylase |
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| halo around the colony where starch has been "eaten", starch plate will be blue/black |
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| reagent in starch hydrolysis test |
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| iodine |
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| enzyme that breaks down peptide bonds between amino acids |
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| gelatinase |
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| positive result of gelatinase test |
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| medium in tube is liquid |
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| enzyme that can breakdown urea |
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| urease |
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| pH indicator of urea broth |
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| phenol red (medium will be yellow orange before inoculation) |
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| color of urea broth if test is positive |
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| ammonia is released and causes the pH of medium to increase. media will change from yellow/red to bright pink Ex. Proteus |
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| Oxidase test is... |
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| DIRECT evidence of ETC |
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| the enzyme that is responsible for transferring electrons to oxygen and reducing them to water. |
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| cytochrome oxidase C |
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| color of DNase agar |
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| sky blue (pretty!) |
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| differential properties of DNase agar |
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| only lets organisms that can enzymatically hydrolyze DNA grow |
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| positive DNase test |
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| plate has clearing (DNA has been eaten up) |
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| negative DNase test |
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| plate is sky blue (DNA has not been eaten) |
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| what type of media is SIM media? |
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| combination differential |
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| three things SIM media looks for |
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| reduction of sulfur, production of indole (due to breakdown of tryptophan), and motility |
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| result of sulfur reducing bacteria in SIM media |
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| black precipitate |
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| result of indole production in SIM media |
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| positive red color from Kovac's reagent |
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| what type of media is the blood agar plate? |
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| enriched and differential |
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| differential properties of blood agar |
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| hemolysis patterns |
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| gamma hemolysis |
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| No breakdown of blood agar |
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| alpha hemolysis |
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| partial clearing/breakdown of blood agar |
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| beta hemolysis |
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| complete clearing/breakdown of blood agar |
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| the enzyme that can coagulate the blood |
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| coagulase Ex. S. aureus |
