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68 terms

ch. 7 Microbial Nutrition

process bywhich chemical substances (nutrients) are acquired from the environment and used in cellular activities
must be provided to an organism
essential nutrients
requited in large quantities, play principla roles in cell structure and metabolism
reuired in small amounts, involved in enzyme function and maintenance of protein structure
micronutrients or trace elements
contain carbon and hydrogen atoms and are usually the products of living things. ex, methane(CH4), carbs, lipids, proteins and nucleic acids
organic nutrients
atom or molecule that contains a combination of atoms other than carbons or hydrogen. ex.-metals and their salts, Magnesium sulfate, ferric nitrate, sodium phosphate, geses-O2 and H20
inorganic nutrients
chemical analysis of microbial cytoplasm
70% water, 96% of cells composed of carbon,hydrogen,oxygen,phospohorous,sulfur and nitrogen
must obtain carbon in an organic form made by other living organisms such as proteins, carbs, lipids and nucleic acids.
an organism that uses CO2 , an inorganic gas as it carbon source. Not nutrionally dependent on other living things
main reservoir of essential nutrients
nitrogen gas, 79% of earth's atmosphere
makes up 20% of earth's atmosphere
major element in all organic compunds and several inorganic
water, salts and gases
roles of H2
maintaining pH, acceptor of O2 during cell respiration,
the main inorgainc compund
phosphate, found in rocks and oceanic materail
key component of nucleic acids and essential to genetics
essential to protein synthesis and membrane formation
important to some types of cell transport
cell wall and endospore stabilizer
component of chlorophyll, a membrane and ribosome stabilizer
component of proteins of cell respiration
organic counds that can't be synthesized by an organism because they lack the genetic and metabolic mechanisms to synthesize them
essential organic nutrients
must be provided as a nutrient
growth facors
gain energy from chemical compounds
gain energy through photosynthesis
two categories if areobic respiration
saprobes-free-living organisms that feed on organic detrius from dead organisms
Parasites-derive nutrients from host
bacteria that exust as normal flora but can cause disease
opportunistic pathogen
can live off host or derive their own nutrients
facultative parasite
doesn't require energy, exist in a gradient and move from higher to lower concentration
passive transport
requires a carrier for diffusion
facilitated diffusion
requires energy and carrier proteins, gradient independent
active transport
net movemnet of molecules down their concentration gradient
totality of organisms to make their own habitat
3 cardinal temeratures
minimum-lowest permitting micribial growth
maximum-highest permitting microbial growth
optimun-promotes fastest rate of growth and metabolism=37 deg C or 98.6 F
3 temperature adaptation groups
psychrophile-optimum temperature below 15 deg C can grow at 0 Deg C
Mesophiles-optimum temp 20-40 deg C
Thermophiles-optimum temp greater than 45 deg C
cells that have developed ezymers to neutralize toxic products(oxidative processes)
superoxide dismutase, catalase
microbes that must live in an oxygen free environment
microbes that utilize oxygen and can detoxify it
can't grow without oxygen
obligate aerobe
ultilizes oxygen but can also grow without it
facultative anerobe
requires only a small amount of oxygen
lacks the enzyme to detoxify oxygen and can't survive in an oxygen environment
obligate anerobe
don't utilize oxygen but can survive and grow in its presence
aerotolerant anerobes
all microbes require this compound in their metabolism
grows best at higher CO2 tensions than normally present in atmosphere
majority of organisms grow at a pH of
between 6 and 8
grow at extreme acid pH
obligate acidophiles
grow at extreme alkaline pH
extreme alkalinophiles
require a high concentration if salt
don't require high concentration of solute but can tolerate it when it occurs
can survide under extreme pressure and will rupture if exposed to normal atmospheric presure
obligatory, dependent, both members benefit
commensal members benefit, other member neither harmed nor benefited
parasite is dependent and benefits,host is harmed
members cooperate to produce a result none could do alone
actions of one organism affect the success or survival of others in the same community(competition)
nonpathogenic residential flora in the human body such as symbiotic bacteria, fungi and a few protozoa
normal microbial flora
result when organisms attatch to a substrate by some form of extracellular matrix that binds them together in complex organized layers. They dominate the structures of most natural enviroments on earth.
communicate and cooperate in the formation and function of biofilsm
quorum sensing
the two levels of microbial growth
increase in size and increase in population
divion of bacterial cells occurs mainly through. the process involves a parent cell that inlarges, duplicates its chromosome and forms a central transverse septum diving the cell into 2 daughter cells
binary fission
time required for a complete fission cycle of bacteria(doubling time)
when each fission cycle increases the population by a factor of 2
exponential growth
equation for calculating population size over time
when populations typically display a predictable pattern over time in laboratory studies
growth curve
lag phase-flat period of adjustment, exponential growth phase-period of maximum growth, stationary phase-rate of cell growth equals rate of cell death by depletion of nutrients and 02, death phase-limiting factors intensify,cells die exponentially
stages of normal growth curve
measures cloudiness, turbidity, reflects the relative population size. the opaqueness of liquid. simplest way to count bacteria
counts all cells present, automated or manual
direct cell count
The complete conversion of superoxide(O2-) ion into harmless oxygen requires a two-step process using these two enzymes(test question)
superoxide dismutase and catalase