Ch. 6 Microbial Growth
Terms in this set (62)
is any material prepared for the growth of bacteria in a lab.
microbes that grow and multiply in or on a culture medium are known as a culture
is needed for AA synthesis, for proteins and nucleic acid synthesis.
Nitrogen can be obtained from?
the decomposition of proteins or from ammonium or nitrate ions.
What bacteria are capable of Nitrogen fixation
rhizobium and cyanobacteria
organisms that req oxygen to live
organisms that can use oxygen when it is present but are able to continue growth by using fermentation or anaerobic respiration when oxygen isn't available.
are bacteria that are unable to use molecular oxygen for energy yielding reactions. in fact most are harmed by it. only anaerobic growth, ceases in presence of oxygen.
only anaerobic growth, but continues in presence of oxygen
only aerobic growth , oxygen is required in low concentrations
what types of bacteria must have the enzyme superoxide dismutase and either catalase or peroxidase to eliminate the toxic peroxide produced as a result of oxygen reduction?
obligate aerobes, facultative anaerobes, obligate anaerobes, aerotolerant anaerobes, and microaerophiles.
the toxic peroxide produced as a result of oxygen reduction are called?
all microbes require?
a carbon source
use glucose and organic material
typically use carbon dioxide, but can also use inorganic material such as cyanobacteria
what is incorporated into nucleic acids
synthesis of thiamin and biotin
Magnesium and potassium
are req as cofactors for enzymes.
Buffers added to a culture medium
salts and sugars work to preserve foods
by creating a hypertonic environment
most bacteria grow best at a pH of
most fungi grow best at a pH of
a culture medium on which only gram positive organisms grow and a yellow halo surrounds S. aureus colonies is called?
a selective and differential medium
a culture medium consisting of agar, peptone, and heef heart is
a complex medium
the source of nutrients in NA (nutrient agar)
is peptone and beef extract
agar is used a a solidifying agent in microbio media?
because few bacteria can degrade it
In a lab cultivation what req reducing media or special growth chambers filled with inert gases?
Vitamin B-1 is an example of what type of growth factor
organic growth factor
Chemically defined medium
a medium in which the exact chemical composition is known
a medium in which the chemical comp varies slightly, from batch to batch (usually due to the nutrient source such as beef broth.
anaerobic growth medium
a medium where oxygen has been chemically removed from the medium aka reducing medium. a chemical like sodium thioglycolate has been added. THis chemical reacts with dissolved oxygen and reduces it to water, with the use of the hydrogen in the medium.
selective (Bias) and differential (commonly dyes for ID distinguishable purposes) medium
by inhibiting unwanted organisms with salts, dyes, or other chemicals, selective media allow growth of only the desired microbes. Differential media are used to distinguish different organisms with the group of bacteria that tolerate the selective process. differentiation of colonies of desired microbes to detectable levels.
what are the two methods to measure microbial growth
direct or indirect method to measure microbial growth
metabolic activity like glucose consumption
most probable number (MPN)
standard plate count
measurement of dry weight
What is one disadvantage of a standard plate count
it will determine the number of viable cells and it does NOT req incubation time.
energy currency necessary for life
common form of bacterial replication. One cell splits and creates two individual cells. this type of bacterial growth refers to an increase in number of bacteria not an increase in the size of the individual cells.
Bacterial Growth Curve
growth at 0 degrees C
growth at 55 degrees C
pathogenic organisms like to grow at this temp. growth at 25 degrees C
growth at 15 degrees C
growth at 85 degrees C. Archaeic bacteria in hot springs is an example
growth in salt.
What specific type of pathogenic bacteria isolated from respiratory or intestinal tracts of humans. They grow best in carbon dioxide incubators.
capnophiles. bacteria isolated has a pH between 6.5-7.5.
refers to an organism that does not use oxygen but tolerates it.
Line B best depicts a psychotroph incubated at zero degrees celsius
false, psychrotrophs may allow slow growths of spoilage bacteria at zero degrees celsius refigerator incubation.
what accumulates on solid surfaces in contact with water and adheres to surfaces
microbes adhere to surface and accumulate as biofilms
form on teeth, contact lenses, and catheters
Which is more resistant to antibiotics microbes in biofilms or free swimming microbes?
microbes in biofilms
why are patients with indwelling catheters more susceptible to infections
because biofilms develop on catheters
in one hospital, Pseudomonas aeruginosa serotype 10 infected the biliary tract of 10% of 1300 patients who underwent gastrointestinal endoscopic procedures. After each use, endoscopes were washed with an automatic reprocessor that flushed detergent and glutaraldehyde through the endoscopes, followed by a tap water rinse. P. aeruginosa 10 was not isolated from the detergent, glutaraldehyde, or tap water. What was the source of infections
The machine itself was the source of infections.
What types of things can you do to prevent biofilm growth on plastic?
One approach to preventing biofilm formation is to incorp. antimicrobials into surfaces on which biofilms might form. Because the chemical signals that allow quorom sensing are essential to biofilm formation, research is underway to determine the makeup of these chemical signals and perhaps block them.
why is S. aureus a facultative halophile?
a facultative halophile by definition do not require high salt concentrations but are able to grow at salt conc. of up to 2 %, a concentration that inhibits the growth of many other organisms. A few species of this can tolerate even 15% salt. S. aureus grows in 7.5% NaCl.
What is the BSL for most intro microbio labs
What is the BSL for a clinical microbio lab working with potentially airborne pathogens, such as tuberculosis bacteria?