Foundational Microbiology 1 Flashcards
The founder of cell biology
Robert Hooke
The founder of microbiology
Antonie van Leeuwenhoek
Protists according to van Leeuwenhoek’s
Protist: any eukaryotic organism that is not an animal, plant, or fungus.
First bacterial cell, and Vertebrate sperm cells
van Leeuwenhoek’s discoveries
bacterial cell = ones that infect your GI system
The founder of taxonomics
Carolus Linnaeus
a system for naming species and grouping similar ones together
Linnaeus described two groups: Animals and Plant
Taxonomics
Binomial Nomenclature: naming includes 2 terms—genus and specific epithet
Genus = generic name
Specific epithet = specific species
the theory of abiogenesis or spontaneous generation – life emerging from non-living matter.
Aristotle
putting spontaneous generation in question. Using sealed containers
Fransisco Redi
supporting spontaneous generation. Boiling broth
John Needham
“There must be a “life force” that causes inanimate matter to spontaneously come to life because he had heated the vials sufficiently to kill everything.”
John Needham
Swan-necked flask experiment. ____ boiled them longer. He concluded that the microbes in the liquid were the progeny of microbes that had been on the dust particles in the air.
Pasteur
Pasteur’s final contribution
Pasteurization: heating grape juice just enough to kill most bacteria without ruining the juice’s taste and other qualities
Pasteur’s 1857 Hypothesis:
The germ theory of disease
- microorganisms are also responsible for disease
Each disease is caused by a specific germ (pathogen)
Studying the etiology of infectious disease
Robert Koch (1843-1910)
Diseases caused by germs are now called ________ __________
infectious diseases
Who is responsible for:
- Simple staining techniques
- First photomicrograph of bacteria
- First photograph of bacteria in diseased tissue
- Use a Petri dish to hold solid growth media
- Transferring bacteria with heat and metal wires
Robert Koch
- The suspected causative agent must be found in every case of the disease and be absent from healthy cases
- The agent must be isolated and grown outside the host
- When the agent is introduced to a healthy, susceptible host, the host must get the disease
- The same agent must be found in the diseased experimental host
Koch’s Postulates
The prevention of disease: 1. Handwashing
Ignaz Semmelweis
Ignaz Semmelweis observed
observed that women giving birth where medical students trained died from puerperal fever 20X more than women birthing at home
- Hypothesized it was due to cadaver particles in med students
- Handwashing with chlorinated lime water decreased mortality
The prevention of disease: 2. Joseph Lister (1850s)
Introduced antiseptic technique and disinfection into surgical theatres
Sprayed phenol on incisions, wounds, dressings, etc.
- Reduced deaths among his patients by 2/3rds
The prevention of disease: 3. Florence Nightingale (1850s)
Introduced antiseptic techniques into nursing practices (Crimean War)—scrubbing furniture, equipment, changing clothes, dressings…
- Highly documented her findings
The prevention of disease: 4. John Snow (1854)
Successfully correlated cholera propagation with poor water sanitation.
This led to the emergence of
2 major branches of microbiology
- Infection control
- Epidemiology
The prevention of disease: 6. Jenner’s Vaccine (1790s)
Jenner’s observations: milkmaids did not get smallpox
Injected 8-year-old boy with pus from milkmaid’s cowpox blisters
Weeks later, he injected the boy with Variola major (bad ethics!)
Most cells do not reproduce immediately even though it’s a nutrient-rich environment.
lag phase
WHY is there a lag phase
- Often, bacteria need to create enzymes in order to metabolize those nutrients
- Or they need to make transport proteins to allow nutrients to enter
- Can last for an hour or days - depends on medium we are using
Cells grow at their maximum rate and there are no limitations to nutrients.
Exponential Phase
As nutrients are depleted and wastes accumulate and we run out of space, the rate of reproduction decreases. Eventually, # of dying cells equals # of cells being produced, and the size of the population remains constant
Stationary Phase
Cells that stay alive during the stationary phase are the ones that are
resistant to stress - these would be the cells that would stay alive through antibiotic resistance
If nutrients are not added and wastes are not removed, a population reaches a point at which cells die at a faster rate than they are produced.
Death Phase
T or F: Not all cells are dead - the number of dying just exceeds the ones being produced
True
Dying cells release nutrients and the remaining cells feed off these nutrients. Can maintain the long-term phase by feeding off this nutrient - can maintain a pretty steady population without adding any new nutrients
Long-term Stationary Phase
the time required for a population of cells to double in number.
generation time
Environmental Factors Affecting Growth:
- solute concentrations/osmosis
2.pH - Temperature
- Oxygen concentration
Psychrophiles
grow best at temp below 15 - can growth below 0
Psychrotolerants
COULD grow in cold but optimal - optimal = 20 ish (infect warm-blooded animals)
Mesophiles
20-40 degrees (our bodies) - most of these are human pathogens
Thermpholes
about 45 degrees (hot springs)
Hyperthermophiles
80-100 - can live in boiling water
Obligate aerobes
(peroxides)—have catalase and peroxidase
Obligate anaerobes
(e.g., clostridia) — do NOT have catalase and peroxidase
Facultative anaerobes
(e.g. E. coli)—aerobes that maintain life via fermentation or anaerobic respiration - they are aerobic but they can still reproduce and grow without oxygen
Aerotolerant anaerobes
(e.g. Lactobacilli)–do not use aerobic metabolism, but they tolerate oxygen - they don’t need oxygen but they can tolerate
Microaerophiles
(e.g. H. pylori)—require oxygen levels of 2% to 10%
microbial communities (usually multiple strains)—have synergistic relationships among numerous microorganisms, attached to smooth surfaces such as teeth, rocks in streams, shower curtains, implanted medical devices (plaque on teeth)
biofilms
____ of bacterial diseases in industrialized nations are caused by biofilms
70%
media - has a wide variety of ingredients that bacteria thrive in. supports a wide variety of growth
complex media
- Good for growing fastidious microorganisms: ones that require a large number of growth factors
contain substances that either favour the growth of particular microorganisms or inhibit the growth of unwanted ones
selective media
Eosin, Methylene Blue, and Bile Salts
kill gram pos. harmless to gram neg
either the presence of visible changes in the medium or differences in the appearance of colonies help us differentiate among the kinds of bacteria growing on the medium
differential media
tube filled with solid agar and add the bacteria with a needle - bacteria grows only where the needle punctured
stab cultured
they enhance the growth of certain species that can then be distinguished from other species by variations in appearance
MacConkey Agar – Selective and Differential
a culture in which all microbes come from a single progenitor cell or isolated colony
a pure culture
- The key – all cells in pure culture are genetically identical
- Requires a high degree of aseptic technique and sterilized equipment
used to isolate the organisms from a mixed population into a pure culture.
THE STREAK PLATE
SERIAL DILUTIONS are used for
measuring populations
turbidity
(indirect & for Large populations)
Greater the bacteria population = more cloudy the broth will be
Cloudier it is = less light coming through - does not reach the reflector
Transmission is inversely proportional to bacteria colony size
