Study Micro 202 Exam 2 Flash Cards
log in to save your progress
Pile Management Card
Micro 202 Exam 2
Micro 202 Exam 2
| enterics |
| -ferment glucose only under anaerobic conditions |
| HE results |
|
-positive for many non-pathogenic enterics (coliforms of E. coli, enterbacter, citrobacter, and non-coliforms that ferment sucrose) (salmon-pink to orange) -if negative, colonies and medium = blue/green (pathogenic, non-coliform, non-sucrose fermenting; Salmonella, Shigella) -Salmonella= green colonies w/ black centers -Shigella= green colonies w/o black centers |
| Common GN genera |
|
-Pseudomonas -Algaligenes -family Enterobacteriaceae -includes genuses: -Escherichia -Enterbacter -Citrobacter -Klebsiella -Salmonella -Shigella -Serratia -Proteus -Providencia |
| Micrococcus |
|
-GP -cocci -tetrads -aerobe -positive for catalase (Staphylo... + too; distinguishes from Streptococci) -salt tolerant -found on skin, in environment (soil, water, air) |
| Denitrification Detection |
|
-selects N2 gas-producing heterotrophs -nitrate broth has C for C and E source -nitrate serves as t.e-.a. -N gas collected in Durham tube -if bubble, + for denitrification |
| Nitrate |
|
-branch pt b/w recycling N within the soil or returning it to gaseous form -used by plants, die, ammonifiied, |
| Denitrification |
|
-formation of N gas from nitrates -soil bacteria causes this to occur -nitrate--> nitrite--> N2O --> N2 -NO3 can serve as t.e-.a. in anaerobic conditions -final end product (N2O or N2) depends on pH of environment -must add fertilizer to replenish nitrates! |
| detection of nitrate |
|
-broth contains only NO2- -nitrate detected by diphenylamine reagent to form blue/black color -make sure all nitrite is removed! |
| detection of nitrification |
|
-use NH4+ to NO2- -use broth with NH4+ as sole N source -has to use NH4+ as E and CO2 as C sources -Trommsdorf reagent w/ H2SO4 -rxs w/ nitrite to form blue-back color -blue/black = + for nitrite |
| assimilatory nitrate reduction |
|
-once in plant cell, nitrates reduced to ammonium and incorporated into aa's -soil doesn't hold to negatively charged NO3 well |
| NItrobacter |
| -oxidizes nitrite to nitrate |
| Nitrosomonas |
| -oxidize ammonium ions to nitrite |
| Nitrification |
|
-NH4 converted to NO2 then to NO3 -aerobic conditions -NO3 principle source of N for protein synthesis in plants -chemoautotrophic (use CO2 as C source and NH3 for E source) -increases nitrate in soil |
| Nessler's reagent |
|
-K2HgI4 -yellow= + for ammoniafication |
| detection of ammoniafication |
|
-peptone-rich broth -amino groups released as NH3 -NH3 detected by Nessler's reagent |
| ammoniafication |
|
-also N fixation -animal wastes and carcasses decomposed by soil microbes to produce aa's -converted into ammonia then ammonium (NH4+) -affected by wide spectrum of bacteria and fungi -NH4+ can be re-released into plants/ other microorganisms -becomes substrate for nitrifying bacteria |
| bacteroids |
|
-irregular shapes -Y-, T-, and club-shaped |
| to ID Rhizobium |
|
-roots/nodules crushed and stained -outside nodules, rod-shaped -inside nodules, bacteroids form |
| excess ammonium |
|
-synthesize aa's -deposited into soil to fertilize other plants |
| Rhizobium |
|
-close association w/ roots (usually legumes) -plants provides anaerobic environment and nutrients from photosynthesis -Rhizobium fixes N for plant -form root nodules packed w/ bacteria -ammonium incorporated into aa's and proteins |
| Azotobacter cells |
|
-ovoid rods -cysts -selected using mannitol salts broth w/ no N source (can only grow if it can fix atmospheric N) -all other N-fixing bacteria require more than just mannitol as E and C source |
| Nonsymbiotic N fixing microbes |
|
-reside in soil -Azotobacter/Azotospirillum (aerobic) -Clostridium (anaerobic) -all fix relatively little N and limited by E available to them |
| 1. Presumptive test |
|
-Most Probable Number (MPN) -will show presence of organisms that ferment lactose and produce gas--> lactose containing broth and Durham tube -estimation of MPN per 100mL -different [] of water sample inoculated into lactose broths, incubated, then checked for acid/gad production -calculate MPN from gas in tubes and compare to safety standards |
| cyanobacteria |
|
-free-living -photosynthetic -fix most N in aquatic environment |
| N fixation |
|
-microbial process where N gas is converted into ammonia (NH3/NH4+) and rapidly assimilated into organic molecules -reverses denitrification -include symbiotic and non-symbiotic |
| N |
| -80% of atmosphere |
| cycle |
| -10-fold range change on semilog paper |
| yogurt |
|
-produced from milk w/ 25% water removed -add 1:1 ratio Streptococus thermophilis (grows faster, primary producer of acid) and Lactobacillus balgaricus (flavor and aroma) -# microbes drops after a few weeks -beneficial bacteria -inhibits undesired organisms (ex: E. coli disappears after 3 days) -anti-cancer effects? |
| fermenting milk products |
|
-extends shelf life -creates new products/flavors -lactic acid maintains protective gut flora -produce vitamins absorbed into body |
| homolactic |
|
-lactic acid primary byproduct -not only byproduct -variations in metabolic pathways produce different dairy products |
| heterolactic species |
|
-lactic acid produced, but not the primary byproduct -not as useful as homolactic -may have = or > amounts CO2, ethanol, acetic acid, organic acids |
| fermented milk |
|
-produce lactic acid as fermentation byproduct--> homolactic or homofermentative species -used in lactic starter cultures to produce butter, cultured buttermilk, other fermented milks, cultured sour cream, yogurt, cottage cheese |
| starter cultures |
|
-ferment milk and create greater shelf life -acidophilis milk (Lactobacillus acidophilis) -bulgarian milk (Lactobacillus bulgaricus) -cultured buttermilk (Streptococcus cremoris, S. lactis) -yogurt (Lactobacillus bulgaricus; Streptococcus thermophilis) -cheese |
| killing microorganisms |
|
-killed exponentially -same % will be killed per unit time -use semilog paper -should be straight line |
| HTST |
|
-71/7C -15 sec |
| LTLT |
|
-62.8C -30 min |
| pasteurization |
|
heating process used to kill most common potential pathogens in milk -does not sterilize -microbes reduced by 90% retard spoilage -heat/time of exposure of milk so that M. tuberculosis (and 4 other pathogenic microbes) are killed - |
| pathogens in cow milk |
|
-lisertia -salmonella -mycobacterium tuberculosis -brucella -coxiella burnetti (rickettsia cause Q fever) |
| common spoiling microorganisms in cow milk |
|
-streptococcus -lactobacillus -microbacterium -pseudomonas -flavobacterium -bacillus -most are harmless |
| cow milk |
|
-sterile, but contaminated at udders -microorganisms introduced eventually spoil the milk |
| Hektoen Enteric |
|
-isolate/ID Salmonella and Shigella -brom thymol blue and acid fushin dyes -toxic to GP and most GN enterics -high [] carbs and peptones -lactose/sucrose present -if either lactose or sucrose fermented, colonies turn salmon pink (+ for fermentation) -bile acids might ppt under low pH conditions -contains sodium thiosulfate and ferric ammonium citrate -if H2S produced--> black colonies (independent of sugar fermentation) |
| E. coli and Salmonella |
|
-both enterics -GN -rods -ferment lactose -produce H2S |
| Salmonella |
|
-many Salmonella strains harmful -infections from Salmonella called salmonellosis -colonies mucous surfaces--> typically in intestinal tract -most severe disease from S. typhii (typhoid fever aka enteric fever, rare today) -mostly in poultry/eggs |
| E. coli |
|
-E. coli O157:H7 contaminates hamburger -has altered genes to cause hemolytic-uremic syndrome--> leads to kidney failure/death -mostly from undercooked hamburgers -many E. coli strains harmless |
| pathogenic food bacteria |
|
-food= nutrient rich -only some strains of E. coli, Salmonella are pathogenic |
| poultry |
|
-contaminated during gutting process -eggs become contaminated with Salmonella via cloaca (passageway for digestive/excretory/reproductive tract) |
| comminute |
|
-ground up meat for burgers, sausage -grinds surface contamination throughout meat -well oxygenated, nutrient rich medium -contaminated fluids |
| beef |
|
-becomes contaminated during slaughter -exacerbated when meat comminuted (ground up) for burgers |
| gut bacteria info |
|
-temp range from 35-38C -can thrive in guts of many species -most harmless/beneficial -some harmful |
| 3. Completed tests |
|
-dark, lactose-fermenting colony of EMB plate streaked onto nutrient agar -positive if lactose fermented, gas produced, organism is GN rod |
| 2. Confirmed test |
|
-performed if + result from presumptive test -confirms if really coliforms -inoculum taken of positive tube ans streaked to EMB plate -reveals dark, lactose-fermenting colonies -E. coli= green metallic -E. coli= always of intestinal origin -Enterobacter and Klebsiella= pink/purple colonies; not always of intestinal origin -little/no color= non-lactose fermenters (may be intestinal GN) |
| standard analysis of water steps |
|
1. presumptive test 2. confirmed test 3. completed test -a negative result from ANY test= no coliforms present in water sample/no fecal contamination |
| EPA water standards |
|
-<2.2 coliforms/100mL water via MPN method -or, 1 coliform/100mL via membrane filtertechnique |
| indicator organisms |
|
-coliforms -most non-pathogenic -GN -non-spore forming -Enterobacteriaceae -aerobic/facultqative anaerobes -ferments lactose -present in large #s in gut -survive longer in water than enterics -E. coli most common |
| human pathogens in water |
|
-bacteria, viruses, fungi, protozoa -caused mostly by fecal contamination of water supply -pathogens of intestinal origin cause diseases related to digestive tract (enteric pathogens) -most fecal contamination not pathogenic -low #s can cause disease |
| potable water |
|
-water intended for human consumption -doesn't have to be free of microorganisms |
| biocode |
|
-produced by adding values of "+" or "-" results gives species name -any 1 species can have several biocodes (from variation in strains) -different biocodes for different strains -normally, a particular 5 digit biocode= 1 species |
| Enterotube II |
|
-for Enterobacteriaceae -12 different media -15 different assays -produces biocode |
| species |
|
-collection of different strains -share many traits and differ from other species -not all strains w/in a species the same: only 90% E. coli ferments lactose -must use different assays to ID species |
| strains |
|
-populations derived from a single cell -like a pure culture -considered clones -may be 100s per species |
| miniaturized test systems |
|
-API 20E System -API Staph-Ident Sytem -Enterotube II -important in clinical setting -takes <5 hrs sometimes |
| Bergey's manual od Systematic Bacteriology |
| -describes all known microorganisms today |
| Urea broth |
|
-contains urea, phenol red (now yellow) -ammonia liberated, raises pH, turns hot pink -Proteus + for urease -Klebsiella gives slow rxn |
| Urease |
|
-urea= amide compound -cleaved by urease to produce ammonia and CO2 -urease produced by Proteus -distinguished from other non-lactose fermenting enteric genera (Salmonella, Shigella) |
| Simmon's citrate agar |
|
-contains only citrate as C and E source -contains pH indicator bromethyl blue -if citrate permease made by cell, CO2 liberated -creates NaCO3--> alkaline (blue) -growth/blue= + for citrate utilization -no growth/green= no citrate utilization |
| Citrate utilization |
|
-citrate= int. of Krebs cycle -some organisms can use citrate as sole E and C source -must produce enzyme citrate permease to absorb citrate into bacterial cell -converted to pyruvate and CO2 -also produce oxaloacetate and acetate |
| Motility |
|
-ability to move via flagella -incolulating needle/stab -spreads if motile -(don't confuse w/ mobile) |
| Kovac's reagent |
|
-contains butanol to extract indole -extracts indole -indole reacts w/ dimethyl amino benzaldehyde of Kovac's reagent |
| SIM (indole) |
|
-tryptophan= aa with indole as R group -tryptophanase needed to cleave indole off -distinguished coliforms -Kovac's reagent -cherry red= + for indole production |
| SIM agar |
|
-SIM agar contains cysteine and sodium thiosulfate -contains ferrous ammonium sulfate -black= positive for H2S -contains tryptone (contains tryptophan) |
| SIM (sulfide) |
|
-cysteine and methionine have S -cysteine desulfurase removes S atom--> alanine produced -produces H2S -H2S can also be produced by reduction of inorganic S compounds, such as thiosulfate -SIM contains cysteine and sodium thiosulfate |
| methyl red |
|
-fermentation of glucose -large amounts of acid? -red= high acid (below 4.5) -orange= int. acid -yellow= low acid (above 5.5) -enterobacter species MR negative -E. coli= MR positive -opposite of phenol red results |
| Durham tube |
|
-if bubble present, then gas liberated (CO2 or H2) -then, + for fermentation -can have fermentation w/o gas production -but not vice-versa |
| phenol red carb tests |
|
-all enterics ferment glucose -phenol red= pH indicator determines if necessary enzymes are present to ferment sucrose, lactose -yellow= + for acid -red= - for acid (or, acids have been neutralized) -contains Durham tube |
| lactose fermentater determining tests |
|
EMB, MacConkey's, phenol red lactose broth -further distinction= methyl red, SIM, citrate, urea tests |
| non-lactose fermenters (enterics) |
|
-Serratia -Providencia -Salmonella -Shigella -Proteus |
| coliform species |
|
-ferment lactose rapidly to produce acid and gas -Escheria -Enterbacter -Klebsiella -Citrobacter -normal flora of human body necessary for good health |
| O/F medium |
|
-oxidation/fermentation -Pseudomonas (not enteric) species can oxidize glucose to produce acidic byproducts only under aerobic conditions -NOT fermentation -distinguishes from enterics -enterics ferment glucose to acidic byproducts only under anaerobic conditions -contains glucose and pH dye -initially slightly alkaline (green) -if acid produced, changes to yellow |
| O/F outcome results |
|
-yellow on top (aerobic), green on bottom (anaerobic): Pseudomonas -all yellow: entero -all green: nuthin' |
| MacConkey's |
|
-distingiushes b/w enteric and non-enteric -selective b/c of crystal violet and bile salts -selects GN -presence of lactose and pH dye differentiates b/w lactose fermenters (coliforms, which give rise to pink or red colonies) -non-lactose fermenters (white colonies) |
| EMB as Selective and differential mediums |
|
-ex: EMB contains lactose -selects for GN or intestinally-derived GP -if able to ferment lactose, produce acid by-products to turn dyes deep blue/purple -GN produce a green sheen when they ferment lactose (E. coli) -E. aerogenes produces dark purple colonies -non-lactose fermentors produce white colonies -basically: EMB differentiates b/w lactose fermentors |
| GN non-enteric genera |
|
-Alcaligenes -Pseudomonas (infection in burn patients, cystic fibrosis patients, meat spoilage) |
| how to distinguish among enteric species |
| -citrates, SIM, urea utilization |
| enteric family |
|
-actually "Anterobacteriaceae" family -includes genera: -Escherichia -Enterobacter -Klebsiella -Citrobacter -Serratia -Proteus -Salmonella -Shigella -Providencia -GN -non-spore forming -rods -facultative anaerobes -ferment glucose |
| enteric pathogens |
| -many intestinal pathogens, though, cause disease related to digestive tract |
| bacteria of intestines |
|
-most not pathogens -imply fecal contamination -includes bacteria, viruses, fungi, protozoans -does not ensure presence of pathogens, but increases likelihood of their presence -many belong to enteric family |
| novobiocin |
| -S. saprophyticus= resistant |
| coagulase |
|
-bacterial enzyme that clots fibrogen in plasma -clotting surrounds organism and physically isolates it from host defenses -S. aureus produces coagulase -latex beads coated w/ plasma proteins -coagulase with cross-link beads, causing clumping -clumping= + for coagulase |
| Mannitol salt agar |
|
-7.5% NaCl= selective for staphylo, micrococcus -S. aureus ferments mannitol, resulting in yellow color -some S. saprophyticus ferment mannitol |
| phenol red glucose broth |
|
-anaerobic conditions -if not fermentative, broth remains red (micrococcus) -if fermentative, broth turns yellow (staphylococcus) |
| distinguishing staphylococcus from micrococcus |
|
-staphlyococcus= facultative anaerobes (can use O2 if present) -grows well w/o O2 to produce acid end products -micrococcus= aerobes, only grow under aerobic conditions -produce H2O, CO2 -mannitol fermentation, coagulase, novobiocin |
| S. aureus |
|
-differentiated by production of coagulase (coagulates blood plasma) -high salt [] tolerance (10%) -produces alpha toxin on blood agar to produce beta-hemolysis -ferments mannitol -most important human pathogen of genus -associated with abscesses, boils, toxic shock syndrome, pneumonia, wound infections |
| Staphylococcus |
|
-GP -facultative anaerobic -cocci -single cells, pairs, grape-like clusters -S. aureus -S. epidermis -S. saprophyticus -positive for catalase -salt tolerant -common in oral, resiratory, and lower digestive tracts, skin, salty or dairy products, brines |
| Streptococcus |
|
-GP -cocci -chains -can ferment in presence of O2 -aerotolerant -coagulase-negative -S. pyrogenes -S. pneunomiae -S. faecalis -no catalase -sensitive to salt |
| catalase |
|
-aerobes/facultative anaerobes -aka peroxidase 2 H2O2 --> 2 H2O + O2 -positive for catalase if bubbles (O2 released) -in Staphylococcus and Micrococcus |
| superoxide dismutase |
|
-enzyme makes H2O2 2O2* +2H+ --> H2O2 + O2 -(H2O2 also toxic to cells, but not as much as superoxide) |
| respiratory chain |
|
-final e- acceptor= O2 -can form superoxide (radical, toxic) -must produce superoxide dismutase to survive |
| alpha-rxn |
|
-very slight clearing -green/yellowish coloration -associated w/ lactic acid bacteria that can partially degrade hemoglobin (produces H2O2) -most oral Steptococci that are not pathogenic |
| beta-rxn |
|
-zone of clearing -caused by B-hemolysins produced in the cells -most Streptococci (except S. pneunomiae) -also, S. aureus and Bacillus -a few scattered B-hemolytic cells not uncommon in healthy swabs |
| gamma-rxn |
|
-no hemolysis -Streptococcus species |
| S. pyrogenes |
|
-associated w/ upper respiratory infections (URI) -scarlet/rheumatic fever -causes strep throat/tonsillitis -from Group A Streptococcus (specific antigen on surface) |
| hemolysis |
|
-disruption of red blood cells (erythrocytes) -zone of clearing if hemolysis occurs |
| Staphylococcus and streptococcus |
| -commonly in skin, skin glands, mucous membranes |
| S. faecalis |
| -recently reclassified as Enterococcus |
| S. pneunomiae |
| -pneumonia and other infections |
| pathogens |
|
-organisms that cause disease -almost all microorganisms can cause disease under right conditions -finding pathogens in healthy individuals common |
| proteolytic enzymes |
|
-hydrolyze proteins -aka proteases |
| Milk agar |
|
-casein= protein imparts white color -must be degraded by exoenzymes to yield aa's for metabolism -not selective (contains glucose, lactose, tryptone, yeast extract) -zone of clearing= produces casein-hydrolyzing exoenzymes |
| Bacillus differential medium |
| -Bacillus= casein hydrolyzer |
| thermoduric Bacillus |
|
-will NOT grow at thermophile temps (45-65C) -can survive up to 80C -Bacillus= mesophile -heating soil sample to 80C kills all non-spore-forming Bacillus -leaves only spores |
| Bacillus spores |
|
-endospores= heat-resistant forms of bacteria that enhance survival -fungal spores= reproductive structure (DO NOT CONFUSE!) -thermoduric |
| Bacillus pathogens |
|
-B. cereus (food poisoning of dairy) -B. anthracis (anthra of cattle/bio warfare agent) -B. thuringiensis (produces Bt toxin fatal to insects; used in corn as insecticide) |
| Bacillus |
|
-GP -rods -mesophiles -produce endospores (only other GP to do so= Clostriudium) -common in soil - |
| Common GP genera |
|
-Bacillus -Streptococcus -Staphylococcus -Micrococcus |
| Differential medium |
|
-enables differentiation based on metabolic differences -ex: blood agar -differences may be seen in colony shape/color of surrounding medium/end-products |
| EMB |
|
-selective medium -eosin/methylene blue dyes -selects for organisms that can survive in bile salts of digestive tract (also can survive in 2 dyes) -selects for GN -selects for GP that can grow in digestive tract |
| selective medium enrichment methods |
|
-give desired species advantage -ex: lactose favors lactose fermentors -lactic acid favors Proprionibacterium species |
| selective medium examples |
|
-low pH favors fungi growth, inhibits bacteria -high salt [] favors Staphylococcus growth |
| selective medium |
|
-helpful to incubate inoculum under exclusive conditions (O2, temp, osmotic pressure, inhibitory substances) -allows growth for some organisms |
| 1st step to ID a species |
|
-reduce microbial load to smaller, more select species -use selective/differential medium |
Place this card into pile:
Copyright © Jadence, LLC 2007 - 2012. All Rights Reserved.