lect 9- microbial growth and control Flashcards
what 2 pathways function during the bacterial cell cycle
DNA replication/partition and cytokinesis
define replisome
group of proteins needed for DNA synthesis
define generation time
double time: time it takes for a population to double
what type of viable counting method yield the most probably number (MPN)
turbidity
what temperature range do psychrophiles function best at
0-20 degrees celsius
what temperature range do psychrotrophs function best at
0-35 degrees celcius
what temperature range do mesophiles function best at
20-45 degrees celsius (human body temperature)
what temperature do thermophiles function best at
55-85 degrees celsius
what temperature do hyperthermophiles function best at
85-113 degrees celsius
what pH range do most bacteria grow at
6.5 to 7.5
what pH range do mold and yeast grow between
5 and 6
define tonicity
measure of osmotic pressure
What do hypertonic environments cause
plasmolysis
where is sulfur found
in amino acids, thiamine and biotin
where is phosphorus found
in DNA, RNA, ATP and membranes (PO43- is source of phosphorus)
define aerotolerance
measure of the ability of a microorganism to grow in the presence/absence of oxygen
what are some ROS
superoxide radical, hydrogen peroxide, hydroxyl radical
what are the protective enzymes that aerobes produce against ROS
superoxide dismutase (SOD), catalase and peroxidase
what are some organic growth factors
vitamins, amino acids, purines and pyrimidines
what does ionization radiation do
disrupts chemical structure of many molecules, including DNA
what does UV radiation do
causes formation of thymine dimers
define disinfection
destruction or removal of vegetative pathogens but not bacterial endospores.
define sterilization
complete removal or destruction of all viable microorganisms
define antisepsis
chemicals applied to body surfaces to destroy or inhibit vegetative pathogens
