Lecture 2 Flashcards
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Aerobic bacteria
grow in the presence of free oxygen
Anaerobic bacteria
grow in the absence of free oxygen
Facultatively anaerobic bacteria
grow in either the absence or presence of free oxygen
Microaerophilic bacteria
grow in the presence of minute quantities of free oxygen
Aerotolerant anaerobes
tolerate presence of oxygen
Heterotrophic bacteria
those bacteria that require an organic carbon source for growth
Oligotroph
any organism which can grow in relatively nutrient poor environments
Mesophiles
grow best in temperatures between 25º to 40ºC. . Most of the microroganisms on earth belong to the group of mesophiles
Xerophiles
live in extreme dry environments
Acidophiles
live in acidic environments
Thermophiles
live and grow in extremely hot environments that would kill most other microorganisms - Grow best at temperatures between 45º to 60ºC.
Alkaliphiles
live in alkaline environments like soda lakes, or alkaline soil
Psychrophiles
live and grow better in temperatures that are about - 0 to 20°C
Halophiles
live and grow in high saline/salty environments
Barophiles
can survive under great pressures
Psychrotrophs
live and grow better in temperatures that are about - 0 to 30°C
If 1ml of inoculum was placed onto an agar plate and 32 colonies were on a plate of 1/1000 dilution, what would the calculation be. Also what would the calculation be if it was 0.5ml of inoculum, 0.25ml, 0.20ml,0.1ml.
1ml - 32x 10,000
- 5ml - 32 x 10,000 x 2
- 25ml - 32 x 10,000 x 4
- 20ml - 32 x 10,000 x 5
- 1ml - 32 x 10,000 x 10
How is the spread plate method more advantageous that the pour plate method?
Colonies develop on the surface of the agar, better for morphology identification
higher bacterial counts
When bacteria multiply into macroscopic, isolated colonies - this is known as..
Colony Forming Units (CFU)
List 2 examples of organisms that can not be grown in laboratory mediums. (They must be grown in cultures containing living human/animal cells)
Syphilis and Leprosy
Heterotrophs
Organic compounds - Carbon source (other feeders)
Autotrophs
Inorganic CO2 - Self Feeders
Allows growth of a single or limited type of bacteria based on a unique combination of nutritional or physiological attributes.
Elective enrichment medium
Microorganisms that are difficult to culture - they have an elaborate requirement for specific nutrients such as vitamins and other growth promoting substances
Fastidious Heterotrophs
Chemical compounds containing mainly carbon, hydrogen, nitrogen, and oxygen
All living organisms are made up of
organic compounds
2 examples of Inorganic compounds: (lacking the properties characteristic of living organism)
Example “hydrochloric and sulfuric acids”
2 major types of nutritional bacteria
Heterotrophs & Autotrophs
2 examples of Heterotrophs
Photoheterotrophs, Chemoheterotrophs
2 examples of Autotrophs
Photoautotrophs and Chemo Autotrophs
2 examples of Autotrophs
Photoautotrophs and Chemoautotrophs
Involves the use of inhibitory substances or conditions to suppress or inhibit the growth of most organisms while allowing the growth of the desired organism
Selective enrichment medium
3 example question that will help make a proper selection of media and physical conditions?
aerobes or anaerobes?
autotrophic and heterotrophic?
thermophilic organisms, or more likely to be mesophilic?
Nitrocellulose filter of pore size 0.45mm is often used to collect the microorganisms and this technique is called
membrane filtration technique.
Two different methods are used for the application of the diluted sample to the growth medium
Spread plate
Pour plate
In the pour plate method aliquots of appropriate sample dilutions are mixed with molten agar to what temperature
45C
Agar exists as a liquid at elevated temperatures but solidifies on cooling to
38ºC
Does agar supply nutritional value to the medium
No
Prepared in the laboratory from materials of precise composition
Synthetic Medium
Contains certain reasonably familiar materials but that varies slightly in chemical composition from batch to batch.
Complex Medium
Heterotrophic plate counts give an indication of the general ______ of the soil as well as an indication of the general availability of organic nutrients within the soil
Health
obtain energy from organic substances
Heterotrophic bacteria
Two basic types of media can be used for this heterotrophic plate count analysis.
nutrient rich and nutrient poor media
nutrient agar, peptone yeast extract agar and soil extract agar amended with glucose and peptone. These media contain high concentrations of peptone, yeast, and/or extracts from beef or soil are examples of what kind of media
Nutrient Rich
media are often called minimal media and contain as much as 75% less of these ingredients, often with substitutions such as casein, glycerol or gelatin. examples - R2A agar, m-HPC agar, soil extract agar with no amendments.
Nutrient poor
It contains ingredients to allow distinction of targeted microorganisms. Lots of different selective agents are used during the target directed isolation of microorganisms e.g., the dye crystal violet inhibits most gram-positive bacteria while allowing the growth of gram-negative bacteria.
Differential medium
Growths of most fungi are inhibited during the_________ through the use of antifungal antibiotics
bacterial isolations
This is normally done by the addition of antibiotics or dyes, such as Rose Bengal, or by lowering the pH of the medium
fungal isolations
1] Periodic transfer to fresh media 2] Preservation of overlaying cultures with mineral oil 3] Preservation of cultures by rapid drying in a frozen state (lyophilization) 4] Storage at very low temperatures
Are examples of
Maintenance and preservation of pure cultures
Some forms of life such as green plants, can utilize radiant energy and they are called
phototrophs.
Forms of life incapable of utilizing radiant energy e.g. animal life rely upon oxidation of chemical compounds for their energy. These are called
chemotrophs
Among the phototrophic bacteria there are species, which utilize CO2 as their principal source of carbon, and these are called
Photolithotrophs
phototrophic bacteria require an organic compound and are called
Photoorganotrophs.
If the bacterial energy derives from oxidation of elemental sulfur and inorganic sulfur compounds these are called
chemolithotrophic bacteria
if a mixture of bacteria is inoculated on a blood-agar medium, some of the bacteria may hemolyze (destroy) the red blood cells where others do not. A clear zone around the colony is evidence of
hemolysis.
Thus, one can distinguish between hemolytic and non-hemolytic bacteria from growth on the same medium.
The temperature of incubation, which allows for most rapid growth during a short period of time (12 to 24h), is known as the
Optimum Growth Temperature
Optimum Growth Temperature
6.5 and 7.5
Although few bacteria can grow at the extremes of the pH range, for most species the minimum and maximum limits fall somewhere between
pH 4 and pH 9
Certain bacteria isolated from brines, salt packs, certain foods, and ocean water called which grow only when the medium contains an unusually high concentration of salt (10 to 15%). This represents an osmotic pressure response
obligate halophilic bacteria
