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necessary in amino acids, proteins, and nucleic acids; most bacteria decompose proteins (NH4+ or NH3-), N2 in nitrogen fixation
necessary in amino acids (cys, met), thiamine and biotin (vitamins); use SO4(2-) or H2S to decompose proteins
necessary inorganic elements required in small amounts usually as enzyme cofactors
EX- zinc, iron, magnesium
grow better with O2, but can grow without it; don't have SOD (superoxide dismutase) so can't make catalase or peroxides
superoxide dismutase (SOD)
enzyme that can neutralize the superoxide free radicals (O2-) which are very toxic to the cell, without this, you can not get rid of O2-
converts hydrogen peroxide to water and oxygen (why hydrogen peroxide bubbles on a wound), human tissues contain this
enzyme that breaks down hydrogen peroxide but differs from catalase in that its reaction does not produce oxygen
used in the cultivation of anaerobic bacteria because otherwise, anaerobes might be killed by exposure; contain chemicals (thioglycollate or oxyrase) that chemically combine with dissolved oxygen and deplete the oxygen in the culture medium
makes it easy to distinguish colonies of different microbes from each other
EX- blood agar
complex polysaccharides used as solidifying agent for culture media
EX- Petri plates, slants, and deeps
a population of cells arising from a single cell or spore (or from a group of attached cells); often called a colony-forming unit (CFU)
the normal reproductive method of bacteria, in which a single cell divides into two identical cells
intense metabolic activity preparing for population growth, but no increase in population; "set-up"
logarithmic, or exponential, increase in population; cellular reproduction (division) most active, cells are most active metabolically
period of equilibrium; microbial death is balanced with the production of new cells; nutrients deplete
population is decreasing at a logarithmic rate; cell death exceeds number of new cells formed
colony counting method: perform dilutions of a sample, inoculate Petri plates from serial dilutions, and after incubation, count colonies on plates that have 25-250 colonies (CFUs)
colony counting method: bacteria are retained on the surface of a membrane filter and then transferred to a culture medium to grow and subsequently be counted
direct microscopic count
colony counting method: the microbes in a measured volume of a bacterial suspension are counted with the use of a specially designed slide
used to measure the turbidity by measuring the amount of light that passes through a suspension of cells; less light transmitted = the more bacterial suspension, counts both the live and dead cells
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