Term
| what is the pH indicator in TSI agar? |
|
Definition
|
|
Term
| what does TSI agar look like uninoculated? inoculated? |
|
Definition
uninoculated - orangish red slant
inoculated - possibly yellow, pink surface, black, gas |
|
|
Term
| what does alkaline reversion in TSI indicate about fermentation ability? |
|
Definition
| sucrose and lactose not fermented |
|
|
Term
| what is the sulfur source in TSI? |
|
Definition
|
|
Term
| what 2 processes cause alkaline reversion in TSI? |
|
Definition
surface oxidation of fermented endproducts to CO2 and H2O
break down of peptones into ammonia |
|
|
Term
| what does urea broth look like? |
|
Definition
| orangish clear, apple juice color |
|
|
Term
| what is the indicator in urea broth? |
|
Definition
|
|
Term
| what does a positive result in urea broth look like? what does it indicate? |
|
Definition
deep pink color
indicates that urea has been broken down into ammonia, CO2, and H2O |
|
|
Term
| what reagant detects indole? what color produced? |
|
Definition
|
|
Term
| what must be present for indole to be produced? |
|
Definition
|
|
Term
|
Definition
| a protein hydrolysate (peptone) than contains tryptophan |
|
|
Term
| what is the pH indicator in methyl red medium? |
|
Definition
|
|
Term
| what type of metabolisme causes red color in methyl red test? |
|
Definition
|
|
Term
| what color is methyl red initially? |
|
Definition
|
|
Term
| what product does Voges Proskauer test for? what metabolism indicated? |
|
Definition
acetoin
butanediol fermentation |
|
|
Term
| what reagants are used in the VP test? |
|
Definition
|
|
Term
| what does KOH do in VP test? what does alpha-naphthol do? what causes the red color? |
|
Definition
KOH - changes acetoin to diacetyl
naphthol - acts as catalyst
red color - diacetyl bonds with guanidine |
|
|
Term
| what does citrate broth look like initially? what is positive result? |
|
Definition
clear
cloudiness or alkaline color change if pH indicator is used |
|
|
Term
| what 2 purposed does LIA agar serve? |
|
Definition
H2S production
lysine metabolism |
|
|
Term
| what does LIA stand for? what does LIA agar look like initially? what indicator? |
|
Definition
Lysine Iron Agar
purple slant
brom cresol purple |
|
|
Term
| if lysine is decarboxylated, what is produced and what does the LIA reaction look like? |
|
Definition
cadaverine
purple color darkens (pH up) |
|
|
Term
| if lysine is deaminated, what does the LIA reaction look like? |
|
Definition
| red and yellow coloration (pH down) |
|
|
Term
| what does the yellow color reaction in LIA indicate? |
|
Definition
|
|
Term
| what type of organisms produce colored colonies on EMB agar? |
|
Definition
|
|
Term
| what does EMB select for? how? |
|
Definition
gram neg. enteric rods
dyes inhibitory |
|
|
Term
| what indicator is used in Hugh Leifson OF medium? what color change if acid is present? |
|
Definition
brom thymol blue
aqua to yellow |
|
|
Term
|
Definition
|
|
Term
| what is OF medium used for? |
|
Definition
| distinguish fermenters from non-fermenters (glucose) |
|
|
Term
| what is tested for with egg yolk agar? what do positive colonies look like? |
|
Definition
ability to hydrolyze lipids
positive growth - clear areas around colonies |
|
|
Term
| what does MRVP medium look like initially? |
|
Definition
|
|
Term
| name a gm + rod that causes food intoxication |
|
Definition
|
|
Term
| name a gram + rod that is a thermophile |
|
Definition
B. stearothermophilus
B. coagulans |
|
|
Term
| what is an improtant diff. between B.stearothermophilus and B. coagulans? |
|
Definition
stearothermophilus - obligate thermophile
coagulans - facultative thermophile |
|
|
Term
| what defines TA spoilage? |
|
Definition
| spoilage caused by a thermophilic anaerobe that does not produce H2S (often Clostridia) |
|
|
Term
| what genus often responsible for 'sulfide stinker' spoilage? |
|
Definition
|
|
Term
| how would you distinguish Clostridium for Desulfotomaculum? |
|
Definition
| abilityt o perform aerobic respiration |
|
|
Term
| name 3 type of spoilage caused by gram positive rods |
|
Definition
flat sour
TA
sulfide stinker |
|
|
Term
| what stains used in a spore stain? |
|
Definition
|
|
Term
| what 3 genera are in the family Micrococcaceae? |
|
Definition
Micrococcus
Staphylococcus
Planococcus |
|
|
Term
| why is Micrococcus a successful spoilage organism? |
|
Definition
thermoduric (can withstand many heat treatments including pasteurization)
salt tolerant (5-15%)
can grow well at low temperatures |
|
|
Term
| how would you distinguish microccus from lactics? |
|
Definition
|
|
Term
| what is skim milk agar used for? what is positive result? |
|
Definition
to determine proteolysis (casein breakdown)
clearing around colonies) |
|
|
Term
| what are 3 methods for examining utensil, equipment, or containers? |
|
Definition
swab method
agar contact
rinse method |
|
|
Term
| what is the name of the utensil surfaces that come into contact with food? |
|
Definition
|
|
Term
| what does RODAC stand for? |
|
Definition
| Replicate Organism Direct Agar Contact |
|
|
Term
| what type of solutions could be used for the rinse method? |
|
Definition
phosphate buffered water
complex rinse solution(w/Tween 80 and sodium thiosulfate)
nutrient broth |
|
|
Term
| what purpose do the ingredients in complex rinse solution achieve? |
|
Definition
|
|
Term
| what is the significant surface of a cup? a plate? |
|
Definition
cup - upper 2 cm of inner and outer rim
plate - and 4x2 cm space that contacts food |
|
|
Term
| how are utensil counts recorded? what numbers are satisfactory? |
|
Definition
colonies/utensil
<100/utensil |
|
|
Term
| how are RODAC counts reported? |
|
Definition
| colonies/4 square inch surface |
|
|
Term
| what agar used to enumerate yeasts and molds? |
|
Definition
| PDA acidulated to 3.5pH with tartaric acid |
|
|
Term
| why must acid be added to PDA after it has been melted and cooled? |
|
Definition
| acid reacts to heat breaking down agar making it unable to solidify |
|
|
Term
| what antibiotics used to select yeasts and molds? |
|
Definition
chlortetracyline
chloramphenicol |
|
|
Term
| what media can be used to encourage spore formation of yeasts? |
|
Definition
| acetate containing media such as McClary sporulation agar |
|
|
Term
| what color are yeast spores when spores stain is performed? |
|
Definition
|
|
Term
| what mold is known as a 'machinery mold' or 'milk mold'? |
|
Definition
|
|
Term
| what mold often implicated in fruit spoilage has heat resistance ascospores and produces a mycotoxin? |
|
Definition
|
|
Term
| what mycotoxin is produced by Byssochlamys? |
|
Definition
|
|
Term
| what yeast is used to make Kefir? |
|
Definition
|
|
Term
| what mold is found on textiles, rubber, leather, and paper as well as food? |
|
Definition
|
|
Term
| what is microbial injury? |
|
Definition
| physiological loss of the ability to grow normally under conditions that would be tolerable to non-injured organisms. caused by sub-lethal stress |
|
|
Term
| where would you expect to find injured bacteria? |
|
Definition
|
|
Term
| what are the 3 major effects of microbial injury? |
|
Definition
1. inability to grow in presence of a selective agent that shouldn't inhibit
2. Need for additional nutrients
3. Extended lag phase after being transferred |
|
|
Term
| how is microbial injury dtermined? |
|
Definition
| sample plated on both selective and non-selective media and results compared |
|
|
Term
| how is microbial injury reversed? |
|
Definition
1. plate on nonselective recovery medium for a few hours
2. Plate on both selective and non-selective
3. Growht should be similar |
|
|
Term
| what 2 areas of food microbiology are most affected by microbial injury? |
|
Definition
1. maintenance of fermentation cultures
2. Design of enumeration procedures |
|
|
Term
| How was injury repair performed in lab? |
|
Definition
Cultures plated on thin layer of nutrient agar
incubated for 1 hr
MacConkey's agar poured on top |
|
|
Term
| what culture credited with first making leavened bread? |
|
Definition
|
|
Term
| what bacteria also used in sausage starters? |
|
Definition
|
|
Term
| what organisms responsible for sauerkraut fermentation? |
|
Definition
Leuconsotoc mesenteroides
Lactobacillus plantarum
Lactobacillus brevis |
|
|
Term
| which of the sauerkraut fermenters is homofermentative? |
|
Definition
|
|
Term
| what is used to measure specific gravity? |
|
Definition
|
|
Term
| what is specific gravity? |
|
Definition
| relative density of a substance compared to specific gravity of water (1.000) |
|
|
Term
| what was added to ground beef to make sausage in lab? |
|
Definition
Pediococcus cerevisiae
glucose
sodium nitrate
salt |
|
|
Term
| how much salt is added to cabbage to make sauerkraut? |
|
Definition
|
|
Term
| what agar used to promote lactic acid bacteria growht? |
|
Definition
|
|
Term
| which lactic forms tetrad? which lactics are rods? |
|
Definition
|
|
Term
| what are the 4 genera of lactics? |
|
Definition
Streptococcus
Pediococcus
Leuconostoc
Lactobacillus |
|
|
Term
| what are the 4 divisions of Streptococcus? |
|
Definition
Pyogenic(needs blood)
Viridans(oral)
Lactic
Enterococcus |
|
|
Term
name a pyogenic Streptococcus.
name a viridan Strep
name a enterococcus Strep |
|
Definition
pyogenic - S.pyogenes
viridan - S.thermophilus
enterococcus - S.faecalis |
|
|
Term
| what strep group cannot grow at 10C or 45 C? which group can grow at both? |
|
Definition
neither - Pyogenic
both - Enterococcus |
|
|
Term
| what are the two divisions of Lactobacillus? |
|
Definition
Streptobacterium
Thermobacterium |
|
|
Term
| which lactics are homofermetative? heterofermentative? both? |
|
Definition
homo - Streptococcus and Pediococcus
hetero - Leuconostoc
both - Lactobacillus |
|
|
Term
| what glycolytic pathway used by homofermenters? |
|
Definition
|
|
Term
| why can't heterofermenters us the Embden-meyerhof pathway? |
|
Definition
| missing enzyme (fructose diphosphate aldolase) |
|
|
Term
| why can't lactics perform respiratory metabolism? |
|
Definition
|
|
Term
| what products do aroma lactics produce? |
|
Definition
| acetoin, diacetyl, lactic acid |
|
|
Term
| why don't normal stains work well in milk? |
|
Definition
|
|
Term
| what stain used for milk samples? what does it consist of? |
|
Definition
Levowitz-Weber stain
modified methylene blue with ethanol and a fat solvent (tetrachlorethane) |
|
|
Term
| what is DMC? what are the advantages? |
|
Definition
Direct Microscopic Count
1. quick
2. reveals types of bacteria
3. reveals leukocytes (sign of mastitis) |
|
|
Term
| what is the difference between DMC and plate counts? |
|
Definition
DMC - total counts
plate counts - viable counts |
|
|
Term
| how do you determine clump count per ml in DMC? |
|
Definition
| multiply avg. count per field by MF (microscope factor) |
|
|
Term
| what is the microscope factor in regards to DMC? |
|
Definition
| refers to the number of fields needed to examine an entire ml of milk |
|
|
Term
| how are clumps of bacteria counted in DMC? |
|
Definition
|
|
Term
| what bacteria involved in yogurt formation? |
|
Definition
Streptococcus thermophilus
Lactococcus bulgaris |
|
|
Term
| what is ripening in regards to cheese? |
|
Definition
| further microbiological and enzymatic changes that occur after they are made |
|
|
Term
| what is an example of an unripened cheese? |
|
Definition
|
|
Term
| what MO used in swiss cheese? |
|
Definition
|
|
Term
| name a surface ripened cheese? |
|
Definition
|
|
Term
| what 7 results can be obtained from litmus milk? |
|
Definition
acid production
alkaline reaction
reduction
gas production
sweet curdling
proteolysis
ropiness |
|
|
Term
| what does an alkaline reaction look like in litmus milk? |
|
Definition
|
|
Term
| what does reduction look like in litmus milk? |
|
Definition
| clearing, white creamy section |
|
|
Term
| how would litus milke with pink at the top, curd formation, and a whitish clearing be reported? |
|
Definition
| acid reduction coagulation |
|
|
Term
| what would proteolysis look like in litmus milk? |
|
Definition
| fairly large amount of water at top |
|
|
Term
| what do the variables n, m, and c represent in quality control? |
|
Definition
n - sample size
c - acceptance number
m - value of deficiency |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| what causes the pink colorization in meats |
|
Definition
|
|
Term
| what causes the brown coloration in meats? |
|
Definition
| oxidation of nitric oxide myoglobin to nitric oxide metmyglobin |
|
|
Term
| why are fresh meats sealed in air permeable filmes and cured meats in airtight films? |
|
Definition
| air keeps fresh meats pink, air makes cured meats turn brown |
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|
