Food micro exam 1 Flashcards
Gram-positive bacteria
Staphylococcus, Listeria monocytogenes, Clostridium botulinum
Gram-negative bacteria
Escherichia coli, Salmmonella
What color is gram-positive
Violet
What color is gram-negative
Red/pink
Orientation and number of flagella in monotrichous
1 at the end
Orientation and number of flagella in Lophotrichous
1 on each end
Orientation and number of flagella in Amphitrichous
Multiple on one side
Orientation and number of flagella in Peritrichous
Multiple all over
Which type of flagellum isn’t polar
Peritrichous
Lag phase
Point where microorganism is getting used to environment
Log (exponential) phase
Point where thee population doubles
Stationary phase
Point where most harmful products are produced. Also max population which leads to same number of organisms living and dying.
Death phase
phase where population declines
Does gram - or gram + require more cells in order to cause an infection?
Gram +
Approximately how many gram + cells are needed in order for an infection to occur?
Thousands to hundreds of thousands
Approximately how many Gram - cells are needed to cause an infection?
As little as 10
What is responsible for majority of food borne illnesses
Viruses
Who definitively disproved spontaneous generation
Louis Pasteur
How was spontaneous generation disproved
With a swan-necked flask experiment
What is Joseph Lister known for?
Sanitation. Created first gas antiseptic (which cleans the air).
What is John Snow know for
He was the first epidemiologist and discovered cholera outbreak in London
Who was penicillin discovered by
Alexander Flemming
Pathway for food borne illness and types of it
Viruses
No derivative
Hepatitis A, Norwalk, Rotaviruses
Pathway for food borne illness and types of it
Bacteria
LOOK AT SLIDE TOO COMPLICATED TO TYPE
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Phylum Firmicutes Gram +
Clostridium, Bacillus, Staphylococcus, Lactic acid bacteria (LAB), Listeria
Phylum Proteobacteria Gram negative
Escherichia, Salmonella, Shigella, Yersinia, Campylobacter, Vibrio, Brucella
Gram-Positive
Thick, peptidoglycan cell wall is the outermost layer. Teichoic acid - antigen
Gram - Negative
Cell walls are thinner and more complex. outer membrane has LPS (endotoxin that causes inflammatory response)
Parasite
Cryptosporidium, Giardia, Cyclospora,taxoplasma
What is the USDA
US Department of Agriculture
FSIS
Food Safety Inspection Service
ARS
Agricultural Research Service
Which regulatory agency cannot issue recalls and which can detain or seize contaminated food?
USDA, FSIS
What is FSMA
Food Safety Modernization Act. Gives FDA the authority to issue recalls
Is the CDC a regulatory Agency
NO
Which food borne illness causes the largest number of deaths (4).
Salmonella Typhi, Taenia solium, Hepatitus A virus, Aflatoxin
Which food borne illnesses are most common (3)
Campylobacter jejuni, non-typhoidal Salmonella, Norovirus.
What is healthy life years
Number of days you are sick in a year
How many food borne pathogens affect the world
31
Does an increase in meat production cause higher or lower death rates for the area
Higher
Does a higher meat consumption cause a higher or lower mortality rate
Lower
Why does a high meat consumption lead to a lower mortality rate?
This indicates access to other products that maintain health. If a person can buy meat it is more likely they have more money.
Which virus has the high infection?
Norovirus
Which pathogen is found mainly in the US and why?
Clostridium perfringens. Because of temperature control
Which pathogen has a Zero Tolerance policy in the US/
Listeria monocytogens
What is non-intact beef
Ground or tenderized beef
Adulteration in non-intact beef
Means it has something bad growing in or on it
What are the 5 major things in the Food System Interconnectedness
Overall health, Food Safety, Nutrition, Food Security, and Sustainability and Security.
What happens if sustainability is compromised?
Food Safety increases
SOURCES OF CONTAMINATION
LOOK AT GRAPH
What is the primary contaminator?
Soil
What are frequent contaminants of produce?
Bacillus, Psuedomonas, Clostridium spp. (does very well in soil and is a spore former)
Raw is risky
Name all sources of contamination (6)
Soil, sewage and manure, air/wind, water, food handling, food processing environment
Should compost be treated and if yes why?
Yes because a long slow bake will not kill off spore formers
What is put in water to clean produce
Chlorine
Does cross-contamination occur more with or without gloves?
With gloves
Is muscle tissue sterile before cutting?
Yes
Which pathogens are commonly found in red meat?
Salmonella and E. coli
Which pathogens are commonly found in poultry?
Campylobacter, Salmonella, and E. coli
What are some carbon sources
Sugars, Polysaccharides, and organic acids
Examples of sugar
glucose, lactose, fructose
Example of polysaccharide
Starch, cellulose
Example of organic acids
Lactate and acetate
What are some sources of Nitrogen?
amino acids?, lipids, proteins, vitamins, minerals, and water
What is an obligate aerobe
Requires oxygen for growth.
Example of obligate anaerobee
Penicillium and Aspergillus
Obligate Anaerobe
Oxygen is poisonous
Example of obligate anaerobe
Clostridium spp.
Facultative anaerobes
Not strict aerobes or anaerobes. Can use oxygen or not
Example of facultative anaerobe
Saccharomycese cerveseige - yeast
Microaerophilic bacteria
Require oxygen levels lower than that found under normal atmospheric conditions
example of microaerophilic bacteria
Campylobacter spp. Found in chicken intestine.
Aerotolerant anaerobes
Don’t use oxygen but are not killed by it
example of Aerotolerant anaerobes
lactic acid bacteria
What happens if pyruvate undergoes glycolysis
Glucose is formed
What happens if pyruvate is in the presence of O2?
Aerobic cellular respiration
What happens if pyruvate doesn’t undergo glycolysis and there is no O2 present?
Fermentation
Glycolysis (EMP pathway)
Glucose broken down to form pyruvate
Where does glycolysis occur?
In the cytoplasm of the cell
What does Glycolysis yield
2 ATP per glucose
What happens when glycolysis transfers electrons from NAD+ to 2 NADH?
It drives the electron transport chain
Where does aerobic (respiration) take place?
The mitochondria
What is the process of Aerobic (respiration)
Pyruvate to Acetyl CoA to Citric Acid Cycle to NADH and FADH2
What is aerobic (respiration) used for
Used in the ETC to generate BIG ENERGY via oxidative phosphorylation (32 ATP)
Does aerobic (respiration) take a long time or does it happen fast
Takes a long time
Anaerobic (fermentation) is the conversion of what to what and what does it yield
Pyruvate to lactase (or another molecule) and yields NAD+ and NADH
How many ATP per glucose does Anaerobic (fermentation) produce
2
How does Anaerobic (fermentation) generate ATP?
Via substrate level phosphorylation in fermentation
Why can’t oxidative phosphorylation occur during fermentation?
Because there is no O2
What are some anaerobic process byproducts?
Acetic acid, lactic acid, alcohol, and gas (CO2)
Which product of anaerobic is from the homolactic pathway
L-Lactate
What is Diacetyl?
Buttery flavor compound
How is diacetyl formed?
LAB pyruvate to pyruvate + acetaldehyde to alpha acetolactate to diacetyl + CO2
How are lipids metabolized?
through lipases secreted by molds. This is an aerobic process
Decarboxylation and deamination
Serine to hydrogen sulfate?
How are samples of possibly contaminated food collected?
Aseptically
What do we do with samples if the numbers detected are low and we are interested in presence or absence?
Enrichment
Dilute when
if high quantities are expected and we are interested in quantification
What is a Standard plate count?
The dilution and plating of colonies to determine population
What is assumption?
Each colony forming unit arises from a single cell
What does S.P.C. rely on in order to find a countable size?
The ability of a cell to grow to a visible size
What are some factors that may affect Colony formation units?
Physiological state, growth conditions, and nutrient availability
What does an aerobic plate count do?
Estimates number of microorganisms in food
What are limitations to APC?
Only estimates a certain category of microorganisms
What type of plating method does APC normally use?
Spread Plate
What would you need to cultivate anaerobes?
Anaerobic hood, anaerobic jars and tubes, modified atmosphere.
What type of plating method does Culturing anaerobes normally use?
Pour plates
What is selective media
Incorporation of ingredients that favor or inhibit growth of particular microorganisms.
What does selective media normally grow?
Antibiotics, salts, and chemicals?
What is the difference between selective and nonselective media
Nonselective medias can grow anything selective media can only grow certain things
How does selective media work?
It inhibits the growth of unwanted organisms
What is differential media?
Incorporation of ingredients that allow differentiation between microorganisms due to biochemical reactions. (indicator dyes + blood)
What is the use for differential media?
It allows for unique looks on plates
Can injured cells still cause disease
Yes
What can cause a cell to be injured
sublethal stress
Why are injured cells dangerous?
They are hard to detect with normal methods and they still express virulent factors
What does Viable but nonculturable (VBNC) mean?
It is in vegetative or dormant state and cannot be cultured by normal means. It can also be fine, but just not in reproductive state
TEST QUESTION!!!
Why are VBNC and injured cells a food safety concern?
They are hard to detect and can still be virulent. A negative test for pathogens in food is never really a negative. There is always room for error and accident.
What is the Most Probable Number?
relatively fast screening method that estimates low number of microorganisms and uses test tubes of broth that enrich and select for particular microorganisms.
Are Most Probable Number tests looking at gram + or -
Mainly Gram -
What do rapid methods do?
Occur within seconds to days. Rapid assays focused on serology genetics etc. Its accuracy is based on sensitivity and specificity. It. uses antibody-based methods and nucleic acid-based methods.
Antibody-based methods
Enzyme-linked immunosorbent assay (ELISA) or Latex agglutination test
What are limitations of Nucleic acid-based methods (PCR, qPCR)
It is never quantifiable, some methods have a high limit of detection, and DON’T ALWAYS TELL YOU IF MICROORGANISM IS ALIVE OR VIRULENT
