BSC 160 1nd Edition Lecture 17 Outline of Last Lecture 1 Bacteria Cells 2 Measuring growth 3 Turbidity 4 Growth in lab culture Outline of Current Lecture 1 Turbidostat 2 Environment Growth 3 Philes Current Lecture Turbidostat uses turbidity to hold growing culture at specific level Can do experiments where you re changing nutrients environment helps keep steady level of growth Start Minimum Top Optimum End Maximum Environment Growth gas requirements Oxygen As oxygen is utilized it s transformed into toxic products Hydrogen peroxide H2O2 O2 O2 OH Most cells have developed enzymes that neutralize these chemicals superoxide dismutase catalase If a microbe is not capable of dealing with toxic oxygen it s forced to live in oxygen free habitats Facultative anaerobe grows just as well as if oxygen is present or not Aero tolerant anaerobe can grow in presence of oxygen doesn t grow better ignores it Capnophile Grows best at higher CO2 tensions than normally present in the atmosphere Neutrophiles Majority of microorganisms grow at a pH between 6 8 Acidophiles grow at extreme acid pH Alkalinophiles grow at extreme alkaline pH Halophiles Require a high concentration of salt Osmotolerant does not require high concentration of solute but can tolerate it when it occurs Barophiles Can survive under extreme pressure and will rupture if exposed to normal atmospheric pressure
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