part 2 Flashcards
physical requirements for growth
temperature
ph
osmotic pressure
chemical requirements for growth
carbon
N,S,P
trace elements
O2/oxygen
organic growth factors
essential elements in chemical requirements for bacterial growth
C, H,O,N,P, S
various components of bacterial structure
carbohydrates, lipids, proteins, nucleic acids
supplied from water added to the culture medium
hydrogen and oxygen
supplied by carbohydrates
carbon
bacteria also get energy in the form of ____ from carbohydrate breakdown
ATP
it is a major components of proteins and nucleic acids.
nitrogen
it is obtained from mainly ammonia, usually in the form of ammonium salts.
nitrogen
are obtained from environment or from deamination of amino acids
ammonium salts
ig is a part of proteins and coenzymes. it is obtained from sulphates
sulphur
many bacteria reduce these ____ to hydrogen sulphide
sulphates
it is required for nucleic acids, ATP coenzymes. etc.
phosphorus
these elements are required in trace amounts and are provided from various food sources
potassium
calcium
magnesium
iron
copper
cobalt
manganese
molybdenum
zinc
required by bacteria for their growth and maintenance
bacterial vitamins
may be essential for some and accessory for other bacteria
growth factor
what are the environmental factors affecting growth?
water
oxygen
carbon dioxide
temperature
hydrogen ion concentration
light
osmotic pressure
symbiosis and antagonism
bacterial cells consist of how many percent of water?
80%
detrimental for most bacteria
ex: treponema pallidum
dehydration
can resist drying for months
staphylococcus
are particularly resistant to dessication and may survive in dry state for several decades
spores
it is a method of preservation of bacteria, viruses and many labile biological materials
freeze drying or lyophilization
bacteria which require oxygen for growth
aerobe
bacteria which do not require oxygen for growth
anaerobe
bacteria which grow only in the presence of oxygen
ex. pseudomonas, bacillus
obligate aerobe
bacteria which are aerobe but can grow with lack of oxygen or in absence of oxygen
ex. streptococci
facultative anaerobe
bacteria which grow with trace amounts of oxygen
ex. listeria monocytogenes
microaerophilic
bacteria which strictly grow in the absence of oxygen. they may die on exposure to oxygen.
ex. clostridia, bacteroides
obligate anaerobes
anaerobes which do not require oxygen but tolerate the presence of oxygen
aerotolerant anaerobes
provided by cellular metabolism and from environment
carbon dioxide
may not produce enough CO2 from cellular metabolism and may require additional CO2 from exogenous sources
fastidious organisms
how many percent of CO2 is supplied for organisms in culture
5-10%
requiring excess amount of CO2
ex. brucella aburtos
capnophilic
variable requirement
temperature
the lowest temperature at which the organisms can survive and replicate
minimum growth temperature
the temperature that organisms grows best and healthiest
optimum growth temperature
the highest temperature at which growth can occur
maximum growth temperature
is the lowest temperature at which all microbes are killed in a 10 mins exposure
thermal death point (TDP)
