Microbiology
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What are some negative (2) and positive (1) outcomes of microbes in food?
pathogenesis, spoilage, and preservation (fermentation)
What is found in food?
Bacteria, fungi, protozoa, and viruses
What makes chicken look slimy when it starts to spoil?
Pseudomonas aerugeinosa
What does morphology mean?
cell shape
What are the different shapes of cells?
coccus, rod, spirilium
what cells have unusual shapes?
spirochetes, appendaged bacteria, and filamentous bacteria
What does nocardia do and what type of bacteria is it?
causes chest infections if you have a weakened immune system and is found in soil. It is filamentous.
What varieties of rod shaped
fat, thin, long, and short
Describe morphology of bacillus.
Large and long rods
Describe morphology of serratia.
short and fat rods
How are different arrangements of bacillus categorized?
diplo-, palisades (dominos), and strepto- (line)
How are different arrangements of cocci categorized?
diplo-, stapylo- (triangle), strepto- (line)
How do we categorize bacteria?
By their ability to retain stains
What are the two categories of bacteria and what colours do they stain?
gram positive (purple) and gram negative (pink)
Describe the thickness of the peptitdoglycan for gram + and - bacteria.
Gram positive (thick) and gram negative (thin)
What does lipopolysaccaride do to you when you are sick?
Gives you a fever
What phases are their in the typical growth of bacteria?
• lag phase • exponential phase • stationary phase • death pahse
Describe the lag phase of bacteria.
Interval between when culture is inoculated and growth begins. Longer in damaged cells.
Describe the exponential phase of bacteria.
The healthiest and most desirable state of bacteria. Varies depending on genetics and environment.
Describe the stationary phase of bacteria
When the growth rate of the population is 0. Essential component is used up or waste accumulates in the medium. Cell functions continue.
Describe the death phase of bacteria
The cells eventually die after stationary phase and in some cases there is cell lysis.
What are endospores?
Spores produced during sporulation that are resistant to heat, hard to destroy, easy to disperse, inhabit soil, and make you sick :(
If there are spores in a bacteria, what does that indicate about he type of bacteria?
It is gram positive, doesn’t matter the colour.
What are 4 distinct parts of the spore?
• Core • Cortex • Spore Coat • Exosporium