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Do the bacteria proliferate during Lag-phase?

  1. Apr 10, 2015 #1
    In various sources I found the different opinions about this. Which one is true?

    http://en.wikipedia.org/wiki/Bacterial_growth

    They say bacteria do not proliferate during lag-phase.



    qUauA18.jpg

    They say bacteria do proliferate during lag-phase.



    oooEXwT.jpg

    They say bacteria do not proliferate during lag-phase.




    F1deWr4.jpg

    They say bacteria do not proliferate during lag-phase.



    yLkOaio.jpg

    They say bacteria do proliferate during lag-phase.



    33lEoki.jpg

    Here are controversial opinions.



    Xk3pEa5.jpg

    They say bacteria do not proliferate during lag-phase.


    So, do the bacteria proliferate during lag-phase, at least insignificantly?
     
  2. jcsd
  3. Apr 10, 2015 #2
    They do not say bacteria do not divide. They say the medium as a whole is not in 'growth stage'.

    Bacteria need the right enzymes for maximum metabolism. It takes a while for the cells to notice the changed growth conditions(which are now completely optimal), signal transduction, gene expression, mRNA translation to produce the proteins that actually start growing at the maximum rate.

    Lag phase is the phase before exponential growth. Growth in the lag phase can be anywhere from negative to anything just below exponential. When in exponential phase, the bacteria all divide at their minimum interval, meaning their number doubles in this time interval.

    Before exponential growth the culture may be in decline, may be growing with a much lower than maximum duplication. The cells usually will be metabolically active, though they don't have to be. If you start out with just endospores, your lag phase will be quite long.


    All these sources are true. They do not contradict. They just don't use words very carefully. If you want to culture up bacteria, then all growth is exponential growth, or you are in suboptimal conditions and you did something wrong, or are still waiting for lag phase to end.
     
  4. Apr 11, 2015 #3
    So, during the lag phase bacteria do proliferate (maybe very insignificantly), right?


    Well, they should, otherwise there will be confusion like this thread :biggrin:
     
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