BSC 160 1nd Edition Lecture 16 Outline of Last Lecture 1 Growth Factor 2 Nutritional Classification 3 Media 4 Ways of growth Outline of Current Lecture 1 Bacteria Cells 2 Measuring growth 3 Turbidity 4 Growth in lab culture Current Lecture Structure of Bacteria Cells Bacterial arrangements Rods Divide in single plane How do we measure growth Change in cell number Change in the turbidity or light scattering of the culture Change in the amount of cell component Colony forming units CFU counting total number of colony on plate but don t know for sure if it was started by single bacteria Turbidity As number of cells increase in a solution they scatter more light How much light is transmitted thru sample Proportional to of microbes Want to look at absorbance Inversely proportional to of bacteria Optical density How much light is scattered as passed thru culture Almost equal to cell growth Rate of Population Growth Charts in notes These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Need to know how many you started with No Need to know generation time for particular microorganism doubling time n Nt No 2 n Growth in lab culture Chart in notes Exponential growth maximum growth period Greatest increase in cell number as long as nutrients are not limiting environment is favorable Stationary phasegrowth rate slows or stops when nutrients become limited or environment changes Death phase dying off exponentially exceeding the number of being replenished Importance Industry how much heat do you need to apply to pasteurize it How can we get around these closed system challenges Keep cultures open Chemostat method continually adding new fresh media and letting old media out Preventing stationary phase by removing limiting factors
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