BSC 160 1nd Edition Lecture 16 Outline of Last Lecture 1. Growth Factor2. Nutritional Classification3. Media4. Ways of growthOutline of Current Lecture 1. Bacteria Cells…2. Measuring growth3. Turbidity4. Growth in lab cultureCurrent LectureStructure of Bacteria CellsBacterial arrangements- Rods- Divide in single planeHow do we measure growth?- Change in cell number- Change in the turbidity or light scattering of the culture- Change in the amount of cell componentColony forming units (CFU)- counting total number of colony on plate, but don’t know for sure if itwas 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) = nNt=(No)2^nGrowth 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 phase- growth rate slows or stops when nutrients become limited orenvironment 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
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