Task 6
Produce an illustrated article for a magazine that examines E. coli structure, growth conditions and curves and how it colonises a new environment. (M2)
Structure
E. coli consists of an outer membrane which contains lipopolysaccharides, a periplasmic space with a peptidoglycan layer, and an inner cytoplasmic membrane. Some strains of bacteria are pileated and capable of accepting and transferring plasmid to and from other bacteria and such property enables the E. coli under stress conditions to survive. It can perform complicated metabolism to maintain its cell growth and cell division, even though it has extremely simple cell structure which has only one chromosomal DNA and a plasmid.
Growth curves
This graph is an exponential
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- Little to no oxygen will result in the E. coli cells producing large quantities of acetic acid, causing the growth medium to reach pH 4 or lower however, with proper aeration the cells will be able to use many organic acids as carbon sources and the pH of the growth medium will be maintained at neutral or basic ranges. Aeration is another important factor in determining E. coli cell growth however it can continue to grow in the absence of oxygen using fermentation and anaerobic respiration.
- Optimal growth temperature is 37C, cannot grow well at temperatures higher than 42C and they can tolerate lower temperatures with lower growth rate.
- The doubling time or generation time for most E. coli strain in a rich medium at 37C is 20 minutes.
- E. coli requires environmental sources of all of the nutrients (carbon, hydrogen, nitrogen, oxygen, phosphorus, sulphur, as well as iron, selenium, calcium, sodium and several others) in order to survive. Most of these elements come from food sources like carbohydrates, proteins and fats. Growth factors can include amino acids, nucleotides, fatty acids or vitamins. The naturally occurring strain of E. coli doesn’t require any growth factors as when the bacterium is given the appropriate elements and energy source, it can synthesise all 20 amino acids, all vitamins, all nucleotides and all fatty acids that it uses during growth and