Food Microbiology Flashcards
1
Q
Known as the “Father of Microbiology” and the first to observe yeast cells, and also the first to observe bacteria and protozoa
A
Antonie van Leeuwenhoek
2
Q
Invented the canning process
A
Nicolas Appert
3
Q
Who patented the tin can?
They issues a British patent to preserve food in glass, pottery, tin & o
A
Peter Durand
4
Q
Who issued a patent for steam sterilization (retort)
A
Raymond Chevallier-Appert
5
Q
Invented the gram staining technique
A
Hans Christian Gram
6
Q
Invented the petri dish
A
Julius Richard Petri
7
Q
They demonstrated that living organisms cause lactic and alcoholic fermentations
A
Louis Pasteur
8
Q
Who was the first person to isolate Salmonella eneteritidis from meat which caused 57 cases of food poisoning?
A
A.A. Gaertner
9
Q
________ is passed in response to Upton Sinclair’s expose of the meat industry in this book, The Jungle
it is an act, series of guidelines
A
Food and Drug Act (FDA)
10
Q
________ first used the term psychrophile for microorganisms that grow at 0 deg C
A
Schmidt-Nielsen
11
Q
identify the bacteria
During the 1900s, ________ caused food poisoning and the first case of diphyllobothriasis was recognized
A
Bacillus cereus
12
Q
The term osmophile was coined by ____ for yeasts that grow well in areas of high osmotic pressure
A
Richter
13
Q
B.W. Hammer first isolated ________ from coagulated milk
A
Bacillus coagulans
14
Q
Who was the first to isolate Geobacillus stearothermophilus from cream-style corn?
A
P.J. Donk
15
Q
During the 1930s, outbreaks of ________ were traced in milk, which lead to the introduction of home refridgerators
A
Campylobacter enteritis
16
Q
identify 2 contributors
These persons demonstrated that perfringens food poisoning is caused by a toxin which lead to Turkey X disease outbreak
think of dunkin donuts and superman
A
C. Duncan and D. Strong
17
Q
identify the disease
In the 1980, foodborne outbreak ____ occurred in the US which was caused by L. monocytogenes
A
Listeriosis
18
Q
idenitfy the bacteria
In 1980, ____ was also first recognized as a pathogen
very common, think of fecal contam
A
E. coli
19
Q
In the year 1980, ____ were also discovered
misfolded proteins
A
prions
20
Q
In 1960, the first commercial facility in the US was designed for ____
a process for extending shelf-life of food
A
Food Irradiation
21
Q
____ was approved for pathogen control in meat and poultry in the 2000s
a process, think of food safety
A
Irradiation
22
Q
identify the diease/outbreak
In 2000, the first report of ____ disease was reported in the US
A
Mad Cow disease
23
Q
identify kind of processing
This processing was indicated by the USDA in 2000, to be used for meat, poultry, processed egg products
A
High Pressure Processing
24
Q
In year 2000, this act was passed which provides preventative controls for both human and animal foods
A
Food Safety Modernization Act
25
It is the ratio the water vapor pressure of food substrate to the vapor pressure of pure water at a certain temp
Water activity
26
# name the bacteria
A water activity of 0.86 or greater indicates the potential growth of ______.
*Staphylococcus aureus*
27
This refers to the tendency of a substance to accept or donate electrons. *It is also related to the availability of O2*.
| an intrinsic parameter
Oxidation-Reduction Potential (ORP) or Redox Potention (Eh)
28
Low ORP values (more negative) are associated with **anaerobic conditions** which gives way to spoilage microbes like ________
*C. botulinum*
29
# identify bacteria species
High ORP values (more positive) are associated with **aerobic conditions** which supports growth of _______
*Pseudomonas* spp.
30
Enumerate the extrinsic parameters of food
| extrinsic - storage environment of food
1. Temperature
2. Humidity
3. Atmospheric conditions
4. Presence and concentration of Gases
4. Presence and activity of other microorganisms
31
# fill in the blanks
Identify the antimicrobial constituents present in the ff:
____ in cloves
____ & ____ in milk
____ in garlic
____ in eggs
1. eugenol
2. casein and lysozyme
3. allicin
4. conalbumin
32
List the intrinsic parameters of food
1. pH
2. Moisture content and water activity
3. Antimicrobial constituents
4. Nutrient content
5. RedOx potential (Eh)
6. Biological structures
33
They have the **widest** pH tolerance
Molds
34
These microorganisms have **relatively high** pH tolerance
Yeasts
35
They have the **narrowest** pH tolerance
Bacteria
36
A water activity that is greater than 0.86 indicates _______.
| it's an acronym
PHF (potentially hazardous food)
37
Fruits generally undergo ____ spoilage
mold and yeast
38
Meats and seafoods have a **final pH greater than 5.6**, making them susceptible to ______ and ________ spoilage
bacterial and fungal
39
*Clostridium botulinum* can grow in **low-acid foods**, with pH of ____.
less than 4.6
40
This is the available water for use by biochemical reactions
Water activity
41
This is an *inhibitory system* which naturally occurs in bovine milk. It is used in the *preservation of raw milk* when refrigeration units are absent
Lactoperoxidase system
42
The lactoperoxidase system consists of 3 things:
1. lactoperoxidase
2. thiocyanate
3. H2O2
43
In the lactoperoxidase system, antimicrobial agents are bacteriostatic against ______
| two different cell types, think of math signs
Gram + bacteria
44
In the lactoperoxidase system, antimicrobial agents are bactericidal against ______.
| think of math signs; it refers to cell type
Gram - bacteria
45
What is the range of TDZ (temperature danger zone)?
4-60 deg C or 40-140 deg F
46
____ is the most important gas used to control microbes in foods
CO2
47
This gas also has antimicrobial properties however it is also *strongly oxidizing*
O3
48
Some organisms produce substances which are lethal/inhibitory to others such as:
* Antibiotics
* Bacteriocins (e.g. Nisin)
* Organic acids
* H2O2
49
Known as "barrier technology" and uses multiple techniques to inhibit microbial growth and extend the shelf life
Hurdle technology
50
State the 3 types of hurdles:
| referring to hurdle technology
1. Physical hurdles
2. Physico-chemical hurdles
3. Microbially-derived hurdles
51
# choose which bacterial species
The predominant microbiota in meat are the following except: *Staphylococcus*, *Micrococcus*, *Pseudomonas*, some yeasts and molds, *Campylobacter* spp.
*Campylobacter* spp.
52
Predominant micobiota in poultry are mostly **psychrotrophic bacteria** primarily ____ and ______ species
***Acinetobacter* and *Moraxella* species**
53
# describe the characteristic of fungal spoilage
*Thamnidium*, *Mucor* and *Rhizopus* species cause ____ in food
whiskers
54
*Cladosporium* exhibit ____ in food
black spots
55
*Geotrichum,* *Sporotrichum* exhibit ____ in food
white spots
56
Green patches in foods are caused by ______.
*Penicillium, Aspergillus*
57
# state the bacteria spp.
Souring (anaerobic spoilage) is caused by bacteria such as:
1. ____
2. ____
3. ____
1. LAB
2. clostridia
3. coliforms
58
Predominant microbiota in finfish varies depending on the environment. Psychrotrophic bacteria such as *Acinetobacter*, *Aeromonas, Shewanella, Flavobacterium, Pseudomonas, Vibrio* thrive in ________ waters.
Temperate
59
Mesophilic bacteria such as *Bacillus, coryneforms, Micrococcus* thrive in ____ waters.
Tropical and subtropical waters
60
Predominant microbiota in shelfish depends on the quality of water. Includes the ff. except:
* *Shewanella putrefaciens*
* *Pseudomonas spp.*
* *Acinetobacter*
* *Salmonella* spp.
* *Moraxella*
All except *Salmonella* spp.
61
A type of differential staining technique to differentiate bacteria into two major groups based on the *structure of their cell walls*
Gram staining
62
Gram + bacteria will appear ____ under the microscope, indicating a *thick peptidoglycan in cell wall*
Blue or purple
63
Gram - bacteria will appear ____ under the microscope which indicates a *thinner peptidoglycan layer in cell wall*
Red or pink
64
Enumerate the steps in Gram staining
1. Primary stain is applied **(crystal violet)**
2. Mordant is applied **(Gram's iodine)**
3. A decolorizer is applied **(Ethyl alcohol)**
4. Counterstain is applied for the last step **(safranin)**
65
What are the steps of Endospore staining?
1. Primary stain **(malachite green)**
2. Mordant **(heat)**
3. Decolorizer **(water)**
4. Counterstain **(safranin)**
66
Enumerate the kinds of **biochemical tests** for bacterial microorganisms
1. Catalase test
2. Oxidase test
3. Carbohydrate Fermentation test
4. IMViC test
5. Motility Test
67
Define the Catalase test
It is a test used to identify bacteria that produces **catalase**, an enzyme that breaks down H2O2 into water and O2 which protects the bacteria from oxidative damage
68
Give the positive and negative indication of Catalase test
* + catalase: formation of bubbles
* - catalase: no production of bubbles
69
It is a test used to identify the presence of **cytochrome c oxidase** which is an enzyme produced by some bacteria involved in the ETC during respiration
Oxidase test
70
Give the positive and negative indications of the Oxidase test
* + oxidase: purple or dark blue color change within 10-20 seconds
* - oxidase: no color change or a faint pink color change
71
This is a test used to identify the ability of bacteria to **ferment carbohydrates, such as glucose, sucrose, mannitol**
Carbohydrate Fermentation test
72
Give the indications for positive and negative carbohydrate fermentation test
* + for acid production: yellow color in the medium
* + for gas production: presence of bubbles or cracks in the medium
* - for carbohydrate test: no color change, no bubbles, no cracks in the medium
73
What is the IMViC test?
The IMViC test is a series of 4 biochemical test that is used to differentiate the members of the Enterobacteriocae family based on their ability to ferment glucose, produce H2S and degrade tryptophan
74
Give the indication for positive result of the IMViC test?
* Indole test: color change to **red **
* Methyl red test: color change to **red **
* Voges-Proskauer test: color change to **red**
* Citrate test: color change from **green to blue **
75
What is the motility testing?
Motility test is used to test the motility of bacteria which is useful for differentiating and identifying different bacterial species
76
What is the indication for positive and negative motility testing
* + Motility testing: bacteria swims through the medium, medium is turbid, bacteria extends from the original inoculation point
* - Motility testing: bacteria will remain localized, medium is clear
77
TRUE or FALSE: *Shigella* species are generally motile while *Shewanella* spp. are generally non-motile
FALSE
| Shewanella - motile
Shigella - nonmotile
78
These are the common foodborne molds:
**1. ____**
**2. ____
3. ____**
1. *Rhizopus* spp.
2. *Muco*r spp.
3. *Aspergillus* spp.
79
Known as the "black bread mold", and is a **spoilage microorganism**
*Rhizopus stolonifer*
80
Known as starter culture for tempeh; also a **beneficial microorganism**
*Rhizopus oligosporus*
81
# identify what species of mold (general)
These mold species exihibit **yellow to green to black rot** in fruits and meats
*Aspergillus* spp.
82
# identify the species of molds
Microorganisms that produce aflatoxins
1. *A. flavus
2. A. parasiticus*
83
# identify species of molds (general)
These species cause **rots in fruits** and some produce **mycotoxins**
*Penicillium* spp.
84
Plays a role in blue cheese production
*P. roqueforti*
85
# identify the species of yeast (general)
These species exhibit **pink, red, orange color**, spoiling refrigerated foods like meat, poultry, seafood, butter
*Rhodotorula* spp.
86
This yeast is found in fruits and vegetables, and is the only species to cause human infections
*Rhodotorula mucilaginosa*
87
These yeasts have hat-shaped ascospore; role in spoilage of picles
*Pichia* spp.
88
# identify pichia spp.
This yeast is found in cheese and other dairy products. Found in plants and crops and also involved in alcohol fermentation
| think membrane
*Pichia membranifaciens*
89
This yeast produces antimicrobial compounds
| think pastor = protect against evil = protect against infections
*Pichia pastoris*
90
Name the culture media and incubation period for the enumeration of foodborne **yeasts and molds**
* culture media: DRBC/DG18 agar, aPDA
* incubation period: 25 C for 5 days
91
What is the culture media and incubation period for the enumeration of **LAB**?
* culture media: MRS (De Man–Rogosa–Sharpe) agar
* incubation period: 35-37 C for 24-48 hours
92
Identify the culture media and incubation period for the enumeration of ***Staphylococcus aureus**
* culture media: BPA (Baird-Parker Agar)
* incubation period: 30 C for 18-24 hours
93
What is the culture media and incubation period for *Bacillus cereus*
* culture media: Bacara agar or MYP (Mannitol-egg yolk-polymyxin) agar
* incubation period: 30 C for 18-24 h
94
# describe the color of colonies
Morphology of *S. aureus*
gray to jet-black in color
95
What is the morphology of *B. cereus*?
| state color
pink-orange color on Bacara agar and pink on MYP
96
What is the bacterial count for *B. cereus* according to BAM?
10-150 colonies/plate
97
Give the IMViC test for **typical *E. coli***
++--
98
What is the IMViC test for **atypical** *E. coli*?
-+--
99
What is the culture media and incubation period during the **presumptive test** of *E. coli*?
* culture media: 3 LST (Lauryl Tryptose) broth
* incubation period: 35 C +/- 0.5 C for 24 +/- 2 hours
100
What is a positive indication for *E. coli* in the **presumptive test**?
gas production
101
What is the culture media and incubation period during the **confirmatory test** of *E. coli*?
* culture media: EC Broth
* incubation period: 24 +/- 2 h at 44.5 C
102
Positive indication of *E. coli* in the confirmatory test
gas production
103
In the **completed test** for the enumeration of *E. coli*, what is the culture media and incubation period?
* culture media: L-EMBA (Levine's eosin methylene blue) agar
* 18-24 h at 35 C +/- 0.5 C
104
# give morphology of colonies
Positive indication of *E. coli* in the completed test
dark centered, flat, with or without a metallic sheen
105
# name the parasite
It is an aerotolerant anaerobe; motility is via pseudopodia, and it produces enterotoxin causing *Amoebiasis*
| foodborne protist
*Entamoeba histolytica*
106
These are small, round structured viruses (SRSV) and the **leading cause of gastroenteritis in the US**
Noroviruses
107
Choose the most unlikely pairing:
a. Meat: Pseudomonas
b. Milk: Bacillus
c. Finfish: Aeromonas
d. Canned goods: Escherichia
d. Canned goods: Escherichia
108
Ropiness or sliminess in milk is an indication of spoilage which is due to certain microorganisms. Which of the ff: is responsible:
A. Coliforms
B. Candida
C. LAB
D. Proteus
A. Coliforms
109
# identify general bacteria spp.
Used as starter culture for yogurt
Streptococcus
110
Starter culture for **flavor and aroma production**
*L. mesenteroides*
111
Motile by **petritrichous flagella** and can grow at **4% NaCl at 10 deg C**. Spoils fish, poultry, water, feces
| think vagina
Vagococcus
112
Species of pediococcus that is used as starter culture in **meat production**
| think damn!
*P. damnosus*
113
# identify spp. of enterococcus
Responsible for the **greening of interior parts of processed meat**
| 2 species
1. *E. faecium
2. E. faecalis*
114
Species of enterococcus responsible for the **yellow pigment on luncheon meat**
| remember cassava (yellow color)
*E. casseliflavus*
115
# what genus
Yeast that is **prevalent in dairy products**, **uses lactose as carbohydrate source and produces lactase **
Kluyveromyces
116
# what genus
Yeast that is prevalent in **dairy products, juice concentrate, and yogurt spoilage **
Debaryomyces
117
# what species of debaromyces
Is halophilic, requiring 24% NaCl and water activity of 0.65
*D. hansenii*
118
# identify spp. of Zygosaccharomyces
____ is aerophilic (aw of 0.62) and ____ is acidophilic (pH 1.8) and causes spoilage in acidic foods like fruit juices
*Z. rouxii*, *Z. bailii*
119
Species of yarrowia known to *break down lipids* and **produce flavor compounds**. It is also found in **meat and dairy products**
| think breaking down (what process)
*Yarrowia lipolytica*
120
# identify the genus
Aerotolerant anaerobes that **produces large amount of propionic acid**. Is also used in **vitamin b12 production**
Propionibacterium
121
Species of propionibacterium that produces **off-flavor in orange juices**
| think orange = round = cyclo
*P. cyclohexanicum*
122
Species of propionibacterium that **is a pigmented contaminant in cheese**
| think toe
*P. thoenii*
123
# identify staph spp.
Present in **fermented meat (e.g. dry sausages)** in combination with **lactobacilli or pediococci**
| think carne (karne)
*S. carnosus*
124
Are aerobic, catalase and oxidase positive, pigmented, and **grow at 5% NaCl**. Common in **shellfish and fish**
Micrococcus
125
Is non-pathogenic, causes **sweet curdling in milk and ropiness in bakery products**
*B. subtilis*
126
Causes **flat-sour spoilage in low-acid canned foods**
*G. stearothermophilus*
127
# identify bacillus spp.
Causes emetic (Fried rice syndrome) and diarrheal syndrome. Motile, and present in production of enzymes
*B. cereus*
128
Give the IMViC test for typical and atypical *E. aerogenes*
| opposite sa typical E. coli and atypical E. coli
typical: --++
atypical: +-++
129
Give the IMViC test for typical and atypical *E. cloacae*
| enterobacter spp.
typical: ++-+
atypical: -+-+
130
Causes typhoid (enteric) fever and systemic infection
*Salmonella typhi*
131
Causes similar infection but is less severe than typhoid
*Salmonella paratyphi*
132
Is used in vinegar production
| AA
*Acetobacter aceti*
133
Is used in cellulose production
| think glucose
Gluconacetobacter
134
Causes gastroenteritis associated with seafoods
*Vibrio parahaemolyticus*
135
# identify pseudomonas spp.
Produces **pyovardin, pyocyanin (blue or green) pigments**. Produces **blue pus**
| think aero
*Pseudomonas aeruginosa*
136
# identify pseudomonas spp.
Spoilage organism of **refrigerated foods (milk, milk products)**
| think fluorescent
*Pseudomonas fluorescens*
137
# identify pseudomonas spp.
Organism that **spoils butter, exhibits ester-like odor**
| think fragments, rhyme with frogey
*Pseudomonas fragi*
138
# identify pseudomonas spp.
Produces **yellow or brownish film spoilage of cottage cheese**
| think viscosity
*Pseudomonas viscosa*
139
Causes **taeniasis**, also known as **beef tapeworm**
*Taenia saginata*
140
Causes **taeniasis**, also known as **pork tapeworm**
*Taena solium*
141
Known as *intestinal roundworm*, prevalent in regions where pork is consumed raw or undercooked
*Trichinella spiralis*
142
A coccidian protozoan, lives in intestinall walls of cats and causes **toxoplasmosis**
| rhymes with mahatma gandhi
*Toxoplasma gondii*
143
A protist that causes colorful blooms
(red tides), produces **saxitoxin** in mollusks and causes **paralytic shellfish poisoning**
Dinoflagellates
144
Bacteria that is capable of **nitrogen fixation** which is essential for soil fertility
*Rhizobium leguminosarum*
145
Causes viral gastroenteritis via **fecal-oral transmission**
Enteroviruses
146
Causes **traveller's diarrhea**, usually affects infants and children
Rotaviruses
147
Are misfolded/infectious proteins, **causes BSE (Bovine spongiform encephalopathy) or mad cow disease**
Prions
148
List the 7 HACCP Principles
1. Conduct a hazard analysis
2. Determine CCPs
3. Establish critical limits
4. Establish monitoring procedures
5. Establish corrective actions
6. Establish verification procedures
7. Establish recordkeeping and documentation
149
A management system and a systematic approach to the **identification, evaluation, and control of food safety hazards**
HACCP
150
Are detailed written procedures outlining steps for cleanliness and sanitation of whole food production process
SSOPs (Sanitation Standard Operating Procedures)
151
Describes the **method, equipment, facilities and controls for producing processed food**
cGMP
152
Green rot in egg is due to ____.
a. Pseudomonas fluorescens
b. Serratia species
c. Proteus species
**a. Pseudomonas fluorescens**
153
Ropiness in bread is due to ___.
a. Mold
b. Fungi
c. Bacteria
**c. Bacteria**
154
Stickiness in meat is due to ___
a. Bacteria
b. Yeast
c. Mold
**c. Mold**
155
Bacterial cells show their greatest resistance to heat during ____ phase.
a. Log phase
b. Late lag phase
c. Stationary phase
**b. Late lag phase**
| This phase is a defense mechanism that allows bacteria to resist heat
156
Butyric acid in milk is produced by the action of ____
a. Cladosporium
b. Clostridium
c. Lactobacillus
**b. Clostridium**
157
^ Fishy odor in eggs is due to ____.
a. E. coli
b. Enterobacter species
c. Pseudomonas species
**a. E. coli**
158
Which of the ff. is the most heat stable toxin?
a. Endotoxin
b. Botulin
c. Ochratoxin
d. Aflatoxin
**a. Endotoxin**
159
Most sugar containing foods that are slightly acidic are spoiled by ____.
a. Bacteria
b. Yeasts
c. Mold
d. All of the above
**b. Yeasts**
| Specifically, osmophilic yeasts
160
^ Putrefaction of butter is due to ____.
a. Eurosic acid
b. Isovaleric acid
c. Elagic acid
d. All of the above
**b. Isovaleric acid**
161
^ Rancidity of meat is due to spoilage by ____.
a. Pseudomonas
b. Achromobacter
c. Yeast
d. All of the above
**D. all of the above**
162
^ Dairy mold is caused by:
a. Aspergillus niger
b. A. flavus
c. A. parasiticus
d. All of the above
***a. A. niger***
163
Traveller's dysentery is caused by:
a. Aflatoxin
b. S. aureus
c. E. coli
d. B. cereus
**c. E. coli**
164
Bacteria responsible for spoilage of vegetables is:
a. Salmonella
b. Erwinia carotovora
c. Shigella dysentariae
d. C. perfringens
**b. Erwinia carotovora**
| Causes soft rot of fleshy vegetables and ornamental plants
165
# identify pseudomonas spp.
Presence of this microorganism causes milk to turn **bright blue**
*Pseudomonas syncyanea*
166
Mycotoxins produced in barley and oats
a. Ochratoxin
b. Sclerotia
c. Citrinin
d. Sterigmatocytin
**d. Sterigmatocytin**
| Usually spoils foods and crops such as wheat, corn, peanut, barley
