M8 Post Lab and Quiz Flashcards by Franchez Cassandra Escander

are relatively more complex than carbohydrates.

proteins
fats

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Breaks down gelatin (hydrolysis) into
sub-components that are smaller
and can easily traverse the CM

gelatinase

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gelatinase are matrix ____

metalloproteases

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are a type of enzyme, specifically a protease, that uses a metal ion, typically zinc, in its catalytic mechanism to break down peptide bonds in proteins.

metalloprotease

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Gelatinase A MMP-_

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Gelatinase B
MMP-_

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is constitutively expressed with broad substrate specificity including types I and IV collagen and requires MT1-MMP and TIMP-2 for activation,

MMP-2

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s inducible, mainly targets type IV collagen, and is activated by proteolytic cleavage or oxidative stress, with TIMP-1 as its main inhibitor

MMP-9

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why do we need to use ice bath in gelatin tube in gelatinase hydrolysis test

The use of an ice bath in the gelatinase hydrolysis test is essential to distinguish true gelatin hydrolysis from simple melting due to temperature.

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common bacteria and rxn with gelatin hydrolysis test

shoes no liquefaction

clostridium perfringens

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bsc of clostridium perfringens

1 or 2

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Degrades lipid

protease

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is a digestive enzyme produced mainly in the pancreas that breaks down fats into smaller components, making them easier for the body to absorb

lipase

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is a secretory product of microbes because it is synthesized inside the microbial cell and then actively transported outside the cell into the surrounding environment, where it performs its function of hydrolyzing lipids

microbial lipase

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are known currently identified as the best lipase producing
bacteria

S. marcescens and P. fluorescens

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bacterial lipases * Production can be affected by specific ___

polysaccharides

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Some are thermostable and most are constitutive and nonspecific in terms of substrate

bacterial lipases

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some bacterial lipases are ___and most are constitutive and nonspecific in terms of substrate

thermostabl

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some bacterial lipases are thermostable and most are ___and ___in terms of substrate

constitutive
nonspecific

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These fatty acids then react with calcium ions present in the medium to form insoluble calcium salts, such as calcium oleate, which appear as a white or opaque precipitate or halo around the microbial colonies.

oleic acid

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The primary component of the medium that acts as a surfactant to aid in lipid
hydrolysis

tween 80

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When lipolytic microorganisms are grown on Sierra’s medium containing Tween 80, they
__ the Tween 80

hydrolyze

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When lipolytic microorganisms are grown on Sierra’s medium containing Tween 80, they
hydrolyze the Tween 80, releasing

fatty acids

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s. The fatty acids then combine with ___in the
medium, forming a cloudy or opaque zone around the bacterial colonies, indicating a positive
reaction.

calcium

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sierra's medium is used to differentiate

serratia species

Milk-based medium used to differentiate bacteria based on their metabolic activities on lactose, casein, and litmus.

litmus milk

litmus medium is composed of

skim milk litmus milk proteins/components

litmus is a what indicator

pH redox indicator

pH that turns litmus into pink

<4.5

pH that turns litmus into blue

pH > 8.3

predominant in litmus milk

lactose

low conc in litmus milk (carbs)

glucose

occurs in colloidal form giving milk its opaque color

casein

soluble proteins in litmus milk

lactalbumin lactoglobulin

– acidity induced coagulation + red coloration (indicative of lactose fermentation)

curdling

Curdling is an indication of

lactose fermentation

curdling is ___ induced coagulation

acidity

if curdling occurs, then there is ___ coloration

red

Lactic acid reacts with casein turning to

caseinogen

f lactose is reduced, ___color may be produced

white

curdling may also form ___, turning into stormy/cloudy fermentation

gasg

gas form in curdling

CO2

digestion of casein that occurs with or without coagulation in acidic or basic medium

peptonization

o Once casein is fully consumed/degraded--> medium becomes

clear/transparent/watery

loss of color (complete ___); in litmus milk

reduction

if previous coagulation is observed, can be more extensive as coagulated casein does not allow rapid O2 diffusion

reduction

alkaline reaction means __ is absent in litmus milk

proteolysis

Acid reaction what color

pink color

pink color means

acid reaction

Pink and solid (white in the lower portion if the litmus is reduced); clot not movable means

acid clot

acid clot result

Pink and solid (white in the lower portion if the litmus is reduced); clot not movable

Fissures in clot means

gas formation

fissures in clot

Clot broken apart means

stormy fermentation

clot broken apart

reduction of litmus

white color (lower portion of medium)

Semisolid and not pink; clear to gray fluid at top means

curd

Clarification of medium; loss of "body" means

digestion of peptone, peptonization

Blue medium or blue band at top means

alkaline reaction

is the color of methyl red at pH higher than 5.1

yellow

A positive litmus test always results in acid production t/f

false

Which of the following results in Litmus tests is not probable? Acid curd: hard curd with clear supernatant (whey) Rennet curd: soft curd followed by peptonization (alkaline pH, superntant brown) Gas production: buggles and coagulated milk Alkaline pH: pink to red color

Alkaline pH: pink to red color

4. A reddish brown color observed on starch agar after addition of iodine solution indicates the presence of sugars with 8-12 glucose units (dextrins) t/f

true

5. Proteins such as lactalbumin and lactoglobulin are left in the whey after the milk has undergone curdling t/f

true

6. Nutrient gelatin which remains fluid at room temperature after an ice bath is indicative of positive (+) proteolytic activity t/f

true

Which of the following will not grow exclusively on citrate? Enterobacter Providencia E. coli Proteus Citrobacter klebsiella

E.coli

Lipolytic activity assessment, in the presence of Ca2+, ___ is precipitated, forming an opaque zone under and around the colony

calcium oleate

10. An anaerogenic fermenter produces gas during carbohydrate fermentation t/f

false

11. One product of citrate utilization is carbon dioxide, which, combined with excess hydrogen in the medium, makes the medium alkaline t/f

false

12. pH indicator in Hugh and Leifson medium

bromothymol blue

13. It is possible for an obligately aerobic organism to have an aerogenic fermentation type of carbohydrate metabolism t/f

false

14. Which of the following will yield a negative VP test? Enterobacter Serratia marcescens Klebsiella salmonella

salmonella

15. ___ and ___ are components of VP reagent

Alpha naphthol and potassium hydroxide

When the bacterium ferments malonate, sodium hydroxide and sodium bicarbonate are formed, which increases the alkalinity of the medium. This shift in pH turns the bromothymol blue indicator in the medium from green to ___

blue

It is possible for an organism to yield positive results for both MR and VP test t/f

true

One possible product of glucose metabolism is acetone t/f

true

Which of the following will not cause starch hydrolysis Bacillus cereus Bacillus subtilis None of the choices All of the choices E. coli

E.coli

___ is the predominant sugar in litmus milk

laco=tose

Amylase is present if the starch agar remains fluid after incubation in an ice bath for 15 minutes t/f

false

____ is the culture medium used to test the ability of an microorganism to use citrate as a sole carbon source

Simmons Citrate Agar

___ is the culture medium used to determine lipolytic activity of microorganisms

Sierra's medium with Tween 80

___ is the clearing of the litmus milk due to the hydrolysis of casein resulting in an alkaline condition (blue or purple) due to release of ammonia

peptonization

Which of the following will yield a negative result in methyl red test? E. aerogenes E. coli Yersinia sp.

E. aerogenes

An inoculated Hugh and Leifson medium with glucose which retained its color after incubation indicates inability of organism to metabolize glucose t/f

true

A pink color developing after a few minutes after Barritt’s reagents are added, indicates the presence of ___

acetoin

This result suggest utilization of citrate as sole source of carbon blue color in simmons citrate agar

true

If the starch has been broken down/hydrolyzed, then there is a clear area that appears in the medium upon addition of Gram’s iodine. This clearing zone indicates the presence of ___

alpha amylase

M8 Post Lab and Quiz Flashcards

(87 cards)