R1 - Microbial growth Lectures Ch. 6 & 5 , Bacterial Diseases of the Respiratory system, Biofilms (ch.4 & 6) Flashcards
Generation Time
The time it takes for one cell to 2 into two cell wall.
Equation for calculating number of bacteria
N = No2^n
Terms for the growth curve/logarithmic growth in order.
- Lag phase
- log/exponential phase
- Stationary phase
- Death phase
Lag Phase
Cells do not immediately reproduce in new medium. So the number of cell changes very little. Microbial population undergoes a period of intense metabolic activity involving synthesis of enzymes and various molecules to start growth.
Log / exponential phase
Cells begin to divide and enter period of growth/logarithmic increase. Cell reproduction is most active by being metabolically active because bacteria cells need to be produced. Binary fission.
Binary fission
prokaryotic cell preproduction by division into two daughter cells.
Stationary phase
Growth rate slow’s, the # of microbial deaths balance number of new cells and population stabilizes. Stabilizes because exhaustion of nutrients and accumulation of waste products and harmful changes in pH play a role.
Death Phase
Number of deaths exceed number of new cells formed.
Direct Methods definition
get an exact cell number
List Direct Methods
- Direct microscopic count,
2. standard plate count
Indirect Methods definition
get a relative number of cels (not exact count)
List of indirect methods
- turbidity
2. dry weight or mass
Direct microscopic count
Direct Measurement.
A measurement volume of a bacterial suspension is placed within a defined area on a microscope. Counting cell under marked square centimeter of slide.
Turbidity
Indirect Method
Fast.
Use spectrophometer, instrument used to measure turbidity (the cloudiness of a suspension)
measures light absorbance of test tube with bacteria
measurements are in O.D. (optical density)
Measurements count live cells and dead cells.
Dry Weight Mass
Indirect method
Fast.
Takes bacteria from growth medium, filters to remove extraneous material, and dried in a desiccator. It is then weighed.
Also measures dead and living cells.
Standard Plate count
Direct Method
1.A series of dilutions of growing bacteria.
Dilutions of 1ml from previous tube is added to 9ml of broth.
2.Grow bacteria on media in petri plates
3.count colonies and calculate cfu/ml
method counts only viable cells
Advantages and Disadvantages of Standard Plate count
Advantages:
Counts only viable cells
can be correlated with turbidity measurement
Disadvantages:
slow
overnight process
Advantages and disadvantages of Direct microscopic count
Advantage:
Quick
Disadvantage:
counts dead cells as well as viable cells
Viable - alive , able to reproduce
What is Binomial Nomenclature?
the system of having two names (genus and specific ) for each organism
e.g. Staphylococcus Aureus (should be italicized or underlined)
Lysosome
Contains Digestive Enzymes that break down various molecules and (some) bacteria
Advantages and disadvantages of Turbidity
Advantages:
Fast
Can correlate to standard plate count but is faster than that.
Disadvantages:
measures viable and dead cells (still absorb light)
Advantages and Disadvantages of Dry Weight or mass
Advantages:
Fast
good for organisms that are clumped together
Disadvantages:
measure living and dead cells
Organisms that obtain carbon source are called?
Autotroph
Heterotroph
Autotroph
Uses inorganic source of carbon such as CO2 e.g.plants
Chemotroph
gets energy from chemicals
- chemolithotroph - chemoorganotroph
Organisms that obtain Energy source are called?
Phototroph
Chemotroph
Phototroph
Light as primary energy source
e.g, plants
Heterotroph
uses an organic source of carbon such as glucose (C6H12O6)
e.g. animals
Chemolithotroph
Chemotroph
- gets electrons and energy from inorganic compounds
e. g. some prokaryotes
Chemoorganotroph
Chemotroph
gets electrons and energy from organic compounds. e.g. animals
Aerobe
Microbes that use molecular oxygen
Anaerobic
don’t use oxygen
Scientific name of Diptheria?
Corynebacterium Diptheriae
Mode of transmission of diptheria?
Respiratory droplets (coughing, sneezing) skin contact (infects humans only) often affects throat (pharynx) and larynx (voicebox)
Diptheria Cell arrangement? shape? scientific name? gram-stain?
scientific name: Corynebacterium Diptheriae
shape: Rod (not consistent)
Gram-stain: Gram Positive
Cell arrangement: some side by side
Toxin of Diptheria?
Exotoxin
a toxic protein, secretes by bacteria
Exotoxin
a toxic protein, secretes by bacteria.
Toxin produces stains cause disease; related bacteria are present on skin and are not pathogenic.
How Diptheria causes disease?
Diphtheria is caused by a pathogenic (disease causing) bacterium Corynebacterium diphtheriae (C. diphtheriae). This bacterium multiplies rapidly spreading through the upper respiratory tract where it causes inflammation. In more serious cases C. diphtheriae produces a toxin which can enter the blood stream to involve the heart, brain and nerves.
Causes suffocation and death, especially in children.
Heart and peripheral nerve damage.
Signs and symptoms of Diptheria?
sore throat low fever couch pseudomembrane with fibrin, dead tissue, bacterial cells
Parts of the body affected by Diptheria?
Lungs (respiratory), pharynx, larynx, skin
Treatment of Diptheria?
Antibiotic and atitoxin
antibiotics such as penicillin and erythromycin
Antitoxin
an antibody that binds to exotoxin made outside of of body.
Pertussis scientific name? shape? gram stain? cell arrangement?
(whooping cough) name:Bordetella pertussis shape: coccobacillus Gram: Gram negative (obligate aerobe) Cell Arrangement: short rods
Obligate aerobe
or strict aerobe
organisms that requires oxygen to live.
Pertussis scientific name?
Bordetella pertussis
Pertussis toxins?
Damage ciliated cells
cause inflammation
impairs immune system.
Also an exotoxin
People most at risk of dying of the disease, Pertussis?
Babies and people with health conditions are the most at risk. Adults and teenagers are affected as well.
Current Vaccine for Pertussis?
the DTaP , contains a subunit of pertussis.
Booster for teens and adults (Tdap)
Stages of Pertussis
First Stage (lasts 1-2 weeks) : regular cold symptons
Second Stage: Severe coughing. “Whoop cough”, difficult to cough up phlegm so use chest muscles. Worst stage that may cause ribs to break in adults, brain damage in babies, and pneumonia.
Third stage: coughing eventually becomes less frequent and less severe.
Symptoms of Pertussis
Starts off as normal cold symptoms but lasts longer than a cold.
Pertussis mode of transmission?
respiratory droplets (coughing and sneezing)
How pertussis causes disease?
contagiouse disease through coughing and sneezing caused by bacteria Bordetella pertussis. It releases a toxin that damages ciliated cells in the respiratory system and causes inflammation.
Parts of body affected by Pertussis?
Toxin damages ciliated cells in respiratory system.
List microbes that grow in temperature conditions?
Mesophil Hyperthermophile Psychophile Thermophile Psychotroph
Microbes that grow under Ph conditions?
Acidophile
Alkaliphile
Microbes that grow in salty environments called?
halophile
Microbes they require oxygen gas
Aerobe
microaerophilic
Pertussis prevention methods
Vaccination" DTaP Vaccinations to babies by 2 months of age Booster for teens and adults (Tdap) Herd Immunity
List anaerobes
obligate anaerobe/ strict anaerobe
aerotolerant
Mesophile
moderate temperature loving microbe optimal growth: 25- 40 degrees Celsius Like human body temperature. On plants and animals May cause disease ; live in terrestrial and aquatic areas
e.g. many bacteria that cause disease are mesophils
Psychrophile
cold loving microbe
Optimum growth: 15 degrees celcius (grow best); like 0 - 20 degrees celcius
In oceans and polar regions, unlikely to spoil foods
e.g. snow algae
Psychotroph
Grow well in refrigerator temperatures
optimal growth: 20-30 degrees celcius
do not grow well at lower temperatures - takes time to spoil foods
causes food spoilage
e.g. molds
Herd Immunity
reduced change of infection of vulneravle individuals if a certain high percentage of individuals in the population are vaccinated or immune.
Thermophile
heat-loving microbe
optimum growth: 50-60 degrees celcius (can with stand 40 and above)
In runoff from hot springs and in compost piles
e.g. Thermus aquaticus
Hyperthermophile
Microbe numbers of the domain archea
Optimal growth: 80 degrees celcius or higher
inside hot springs and deep sea hydrothermal vents
e.g. Sulfolobus, an arches, live in yellowstone.
Treatments for Pertussis?
Best to have catched/noticed it earlier.
First stage treatment - antibiotics
second stage - antibiotics don’t help signs and symptoms in 2nd stage.
Acidophile
tolerant of acidity
is in foods such as yogurt and cheese
e. g. molds pH 5 , archeans at very low pH in yellowstone
e. g. Lactobacilus bacteria in yogurt
Alkaliphile
like basic environment
Microaerophilic
uses small amounts of oxygen
requiring oxygen for growth but at lower concentration than is present in the atmosphere
Aerotolerant
cannot use oxygen for growth but they tolerate them fairly well.
Bacterial methods of reproduction
Bacteria normally reproduce by binary fission or budding.
Budding - form a small initial outgrowth (a bud) that enlarges until is size approaches that of the parent cell and then it separates.
binary fission - prokaryote cell reproduction by division into two daughter cells.
Describe at least 3 Advantages to a bacterium of living in bioflm.
- Prevents dehydration
- Shares nutrients
- protection from host immune system; antibodies and phagocytosis
What are examples of biofilms? Where are they found?
They are found on solid surfaces with moisture.
Slimy stuff on rocks in pond water or rivers. Plaque on teeth of animals mouths.
Can form on medical devices such as artificial hips.
In lungs of cystic fibrosis patiends.
Why are biofilms potentially dangerous to human health?
- 70% of human bacterial infections involve biofilms.
- Can form on cavities on teeth.
medical devices from surgery can later on cause infections.
Who is particularly susceptible to biofilm infections?
Those who do not maintain dental hygiene. Patients with medical devices an low immune systems.
What is an EPS?
Extracellular Polymeric substance - a glycocalyx that helps cells in a biofilm attach to their target environment.
EPS is the new word for slime layer.
No stand for in equation for calculating bacteria
is the number of cells at the beginning
N stands for in equation for calculating number of bacteria
the total number of bacteria at the end
n
number of generations
