Microbiology Day 9 - Microbiology Day 9 Bacterial Growth...

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Microbiology Day 9 Bacterial Growth Slide 25 Different stages and steps and important things, this is population growth and cell growth is meant for cell. Sometimes they mix the names. Lag phase, and this is time it takes for bacteria to go from situation where they don’t grow to where they grow, to express genes to allow growth and happens at many different places Time takes to express genes required for growth in a new environment Examples: 1) Is whenever you grow cells and want to keep them, you store them in -80 freezer, so put in glycerine or DSHL. So if you have frozen stocks, cell lines that you’ve kept at -80 degrees in either 15% glycerol or DMSL (Check). So you grow culture, spin it out, add this chemical and put them directly in freezer. You then take them out of freezer to whatever medium (agar), so it takes time to make new proteins and start growing, since not all cells are at beginning of cell cycle and they are everywhere. So if you take them out and they started to grow, you wouldn’t have lag phase and that’s one time you would see lag phase. Repeated freezing/thawing? Lysis, freezing/thawing causes lysis and it breaks them open, so you store multiple samples of a stock (20-100), because it depends on lab and generally, you only take it out once because they are more fragile. 2) Another place is when you’re diluting culture from stationary phase back to exponential (log phse), in new medium. Why wouldn’t you use old medium? (So spin cells and get rid of half of them). Problems is that there is waste (pH is changes), and a lack of nutrient. So you can induce stationary phase by lack of nutrients So if you setup new culture, NEED new medium 3) When they come from a normal environment to a media environment, like soil to rich broth (lab), so anything that affects ability to grow, stop growing for some case, slow down and then put them in richer system, they’ll make new protein, changing temperature and changing new nutrients. So changing medium and choice of nutrient also affects this.
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