Microbiology Flashcards
1
Q
What are some negative (2) and positive (1) outcomes of microbes in food?
A
pathogenesis, spoilage, and preservation (fermentation)
2
Q
What is found in food?
A
Bacteria, fungi, protozoa, and viruses
3
Q
What makes chicken look slimy when it starts to spoil?
A
Pseudomonas aerugeinosa
4
Q
What does morphology mean?
A
cell shape
5
Q
What are the different shapes of cells?
A
coccus, rod, spirilium
6
Q
what cells have unusual shapes?
A
spirochetes, appendaged bacteria, and filamentous bacteria
7
Q
What does nocardia do and what type of bacteria is it?
A
causes chest infections if you have a weakened immune system and is found in soil. It is filamentous.
8
Q
What varieties of rod shaped
A
fat, thin, long, and short
9
Q
Describe morphology of bacillus.
A
Large and long rods
10
Q
Describe morphology of serratia.
A
short and fat rods
11
Q
How are different arrangements of bacillus categorized?
A
diplo-, palisades (dominos), and strepto- (line)
12
Q
How are different arrangements of cocci categorized?
A
diplo-, stapylo- (triangle), strepto- (line)
13
Q
How do we categorize bacteria?
A
By their ability to retain stains
14
Q
What are the two categories of bacteria and what colours do they stain?
A
gram positive (purple) and gram negative (pink)
15
Q
Describe the thickness of the peptitdoglycan for gram + and - bacteria.
A
Gram positive (thick) and gram negative (thin)
16
Q
What does lipopolysaccaride do to you when you are sick?
A
Gives you a fever
17
Q
What phases are their in the typical growth of bacteria?
A
- lag phase
- exponential phase
- stationary phase
- death pahse
18
Q
Describe the lag phase of bacteria.
A
Interval between when culture is inoculated and growth begins. Longer in damaged cells.
19
Q
Describe the exponential phase of bacteria.
A
The healthiest and most desirable state of bacteria. Varies depending on genetics and environment.
20
Q
Describe the stationary phase of bacteria
A
When the growth rate of the population is 0. Essential component is used up or waste accumulates in the medium. Cell functions continue.
21
Q
Describe the death phase of bacteria
A
The cells eventually die after stationary phase and in some cases there is cell lysis.
22
Q
What are endospores?
A
Spores produced during sporulation that are resistant to heat, hard to destroy, easy to disperse, inhabit soil, and make you sick :(
23
Q
If there are spores in a bacteria, what does that indicate about he type of bacteria?
A
It is gram positive, doesn’t matter the colour.
24
Q
What are 4 distinct parts of the spore?
A
- Core
- Cortex
- Spore Coat
- Exosporium
25
What is the exosporium?
The thin outermost layer, protein covering
26
What are spore coats?
Layers of spore-specific proteins
27
What is the spore cortex?
Loosely cross-linked peptidoglcan, part of what was in cell wall
28
What is the core or spore protoplast?
Contains a core wall, cytoplasmic membrane, cytoplasm, and nucleoid, and ribosomes
29
What does the endospore core contain?
High levels of dipicolinic acid, gel-like cytoplasm consistency, and high levels of small acid soluble proteins (SASPs)
30
What does dopicolinic acid do?
Reduces water content of spore when spore is (essentially) asleep
31
Why is the cytoplasm at the endospore core gel-like?
Because it increases heat and chemical resistant when enzymes are inactive. Low amount of water.
32
How do small acid soluble proteins (SASP) aid the endospore core?
By binding tightly to DNA to protect from destruction
33
When does formation of spores occur?
When cells are done growing and key nutrients are limited. There are many stages and genes involved in this process.
34
What bacteria is the most heat resistant?
E. coli and S. aureus
35
Are bacteria with endospores more or less heat resistant?
less heat resistant. But some endospores are more resistant than others.
36
Describe yeast
unicellular, grow in wide range of conditions, and grows faster than mold but slower than bacteria
37
Describe mold
multi- or uni-cellular and are found in decaying matter. They form mycelium composed of hyphae. May produce toxins, antibiotics, and enzymes that are useful in food industry
38
What spores do molds multiply by?
conidia spores
39
Describe protozoan parasites.
single-celled eukaryotes that must have a hose. They cannot culture on plates and must be detected directly. Ingestion causes illness and may involve multiple animal hosts.
40
Describe food borne viruses.
Obligate parasites that are host specific and associated with food. They cannot replicate in food/water and are hard to detect. Can only be transmited via fecal-oral transmission.
41
What are some sources of microbes in food?
Soil, water, plants, food utensils, GIT, mamary tissue, food handling, animal feed, animal hides, air and dust
42
Why shouldn't you eat mussels?
Filter out toxins from the ocean that are heat resistant. They are more toxic in warmer water bc planktons grow there.
43
Why does grinding increase the amount of microbes in meat?
Because the inside of meat is essentially sterile and the outside contains microbes so you grind in the microbes and have to cook it more to kill.
44
Why do you need to cook tenderized steak more?
Because needles that pierce the steak put bacteria into food.
45
When/how does contamination in produce happen?
During harvesting when water and fertilizer initial deposits of contaminants. This can be eliminated by composting.
46
Why shouldn't you drink raw milk?
milk has a shit-ton of bacteria, pathogens, and obligate aerobes
47
What is the hardest pathogen to kill in dairy?
Coxiella
48
What are sources of contamination?
hay, grass, animal feeds, water, soil, equipment
49
How does pectinase (in cellulose) in carbohydrates cause food spoilage?
It cleaves monomers from polymers causing produce to soften.
50
What do dextrans (produced by leuconostoc mesenteroides and bacillus mesentericus-slimy) do to produce?
Alters the texture/flavour, causes the consistency of juice to by ropy, and a slime layer on produce.
51
How do proteins aid in food spoilage?
Degrade sugar in tissue and metabolize the proteins producing biogenic amines. This produces a smelly by-product from fungi and mold (black, white, or fuzzy).
52
What are the preferred energy source for microbes?
carbohydrates (glucose before lactose). If low CHOs then protein for energy.
53
Why are processed meats worse for you?
Because they are high in carbohydrates and therefore support rapid growth of microbes.
54
What factors affect microbial growth?
nutrients, water activity, temperature, O2, pH, physical properties, applied ingredients
55
What is the hurdle concept?
One that employs multiple antimicrobial factors.
56
What is the hurdle philosophy?
Multiple parameters employed to obtain similar growth inhibition.
57
Describe bacteria respiration
Electrons extracted from substrate molecules and move across membranes into acceptor molecules from high to low energy states. Protons are extruded along the way to the periplasm in gram (-) bacteria. This drives ATP synthesis.
58
What is the process of fermentation when O2 is absent?
No proton gradient, one part of substrate is oxidized while other is reduced. ATP is generated in the substrate level, defining fermentation.
59
What is a homofermentator and what is an example of what it produces?
Produces a single compound like lactic acid.
60
What is a heterofermentator?
Produces more than one compound like lactic acid and ethanol.
61
What is used in the fermentation of milk and what does it produce?
lactic acid bacteria to lower pH and produce lactic acid from lactose.
62
At what pH does milk for gel and at what pH does protein from milk precipitate?
5.2-gel and 4.6 precipitate
63
Describe meat fermentation
Meat is fermented by desired microorganisms then lactic acid lowers pH and aids in flavour and colour development creating summer sausage.
64
How does fermentation of vegetables and fruit occur?
pH lowers creating an anaerobic environment, salt is added killing gram(-) bacteria, forms lactic acid and CO2.
65
What is the latency period of contracting a pathogen?
From the time you obtain the bacteria/virus to the time you exhibit symptoms.
66
What is the persistance/die off of pathogens?
How long they survive for.
67
What is the infective dose of pathogens?
How much you must ingest to get sick
68
What does the species strain of a pathogen matter?
Because it determines if you can get sick from it. You body will tolerate some.
69
What are some factors from the host influence whether or not they will contract a food borne illness.
Immunity, infection, vaccination, antibodies from breast milk, age, health status, nutrition, hygiene
70
Describe some routes of fecal-oral transmission.
Hands to person, insects, water, crops, soil. All in food (#1).
71
What is a foodborne infection?
Something which occurs when viable pathogens (bacteria, viruses, or parasites) are ingested with food and multiply in the human body. Symptons can last 1-50 days.
72
What symptoms may be included in foodborne infection?
fever/chills, malaise, headache, vomiting, diarrhea, dehydration intestinal crmaping, arthritis, septicemia, miscarriage/stillbirth, death
73
Describe listeria monocytogenes.
They are gram positive ad are widely distributed through environmental waste. They proliferate under high salt, low pH, and high humidity. Meat, shredded cheese, apples, salad mixes, etc. (this shit is dangerous)
74
Describe food borne intoxication.
Occurs when foods are ingested that already contain toxins produced by bacteria or mould.
75
What is the difference between foodborne infection and intoxication?
Infection multiples inside body whereas intoxication multiplies in food source before being ingested. e.g. food left on stove overnight.
76
What is the rate of symptom onset in the case of foodborne intoxication?
Within minutes to 15 hours. Very fast because toxin is already prevalent.
77
If you get a fever after eating food what does that indicate about the type of bacteria you have ingested.
If you have a fever it is gram-negative, if no fever it is gram negative.
78
Describe staphylococcus
A foodborne intoxication that is gram positive. People got sick from maple bacon jam in 2013.
79
What are mycotoxins?
Poison from fungus, found on agricultural products
80
What is claviceps purpurea?
A mycotoxin that produces an alkaloid toxin causing victims to hallucinate. This is from ingesting affected bread/wheat contaminated with ergot.
81
What is yellow rice?
Rice contaminated with penicillium and causes liver damage.
82
What is Turkey X disease?
Aspergillus flavus contaminated feed. They fed this to turkeys which killed >100,000 turkeys.
83
What is alimentary toxic aleukia?
Caused by bread contaminated with trichocenes from fusarim spp. May cause dermal necrosis, hemorrhaging, and bone degredation.
84
EHEC Symptoms
1. Hemolytic uremic syndrome (anemia and renal failure)
2. HC-bloody diarrhea, severe abdominal cramps, nausea, vomiting, fever
4. Throbotic thrombocytopenia purpura (death is common, involves CNS)
85
What is E. coli linked to?
unpasteurized juice, raw milk, undercooked gorund beef, salad/spinach, raw vegetables
86
Describe the mechanism for parasititic infection.
Oocysts are excreted and get back into the environment, infecting water and soil.
87
What are 2 very common viruses?
Hepatitis A and norovirus (most common)
88
What system is used to prevent food borne illness?
A preventative system. The Hazard Analysis Critical Control Point System
89
What are the 7 principles of HACCP?
1. Asses hazard/risk
2. Determine how to control hazard
3. Establish critical limits
4. Establish monitoring procedure
5. Establish corrective actions
6. Establish HACCP procedure validation methods
7. Establish effective record and documentation system
90
What is FSEP?
The Food Safety Enhancement Program
