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WJEC A2 Biology By4.4 Microbiology


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WJEC A2 Biology By4.4 Microbiology

  1. 1. Matthew Higgins WJEC A2 BIOLOGY TOPIC 4.4 MICROBIOLOGY
  2. 2. Microorganisms? Bacteria Protoctista Fungi Viruses
  3. 3. THING 1 CLASSIFYING BACTERIA Image by kliefi
  4. 4. Bacteria Shapes Bacillus Rod Shaped Cocci Spherical Spirillum Spiral Shaped
  5. 5. Gram Staining Bacteria Plasma Membrane Plasma Membrane Peptidoglycan Layer Lipopolysaccharide Layer Gram Positive Gram Negative Examples; Listeria, Bacillus Examples; E. Coli, Salmonella Retain dyes like crystal violet, so appear blue/purple Do not retain dyes like crystal violet, so appear red
  6. 6. THING 2 GROWING BACTERIA Image by kaibara
  7. 7. Growing Bacteria It needs to be the right temperature this is usually 25-45℃ The bacteria will need some nutrients agar is often used in the lab Everything needs to be at the right pH this is about 7.4 (slightly alkaline) for most bacteria, but most fungi like it more acidic There needs to be enough oxygen, but not too much different bacteria require different amounts of oxygen •Obligate aerobes only live where there is oxygen •Facultative aerobes don’t mind either way, but grow better with oxygen •Obligate anaerobes can not grow in the presence of oxygen, like Clostridium, which cause gangrene
  8. 8. Bacteria Life Cycle Time PopulationSize 1 2 3 4 5 Lag Little growth, cells take up water, carry out protein synthesis and produce enzymes Log Rapid (exponential) increase in population size Death More cells die than are produced Stationary Cells die at a similar rate as they are produced
  9. 9. Working Safely Prevent contamination from the environment by sterilising everything before starting and handle everything carefully using appropriate equipment Handle everything correctly by flaming the mouth of the bottle, passing the innoculating loop through the flame, only lifting the lid of the petri dish just enough, taping the lid to the petri dish in two places Sterilise all equipment in an autoclave this is a sealed container which is heated to 121℃ at a high pressure for 15 minutes, which ensures all pathogens are destroyed. Commercially, radiation works just as well. Prevent contamination to the environment by sterilising the working area before and after working with disinfectant
  10. 10. Recording Growth Total Count Count every single cell, living or dead Viable Count Count the living cells only Serial Dilution 10cm3, which contains 4000 cells, in a test tube 9cm3 distilled water, and 1cm3 from the last test tube, so there’s 400 cells 9cm3 distilled water, and 1cm3 from the last test tube, so now there’s 40 cells 1cm from the last test tube gives four colonies Haemocytometer A microscope slide that allows you to count red blood cells. It’s only useful for giving a total count. Turbidimetry A specialised colorimeter measures the turbidity (cloudiness) of a mixture which lowers as the size of a population increases
  11. 11. THING 3 FERMENTERS Image by hopwild
  12. 12. Fermenter Design Culture The fermenter requires a pure culture , this eliminates competition giving maximum efficiency ! "#$%&'() *'+, Arholwr yn unig 2. 45(67&$8)$%695*:96$'6&'7;9<)&$+6=()%('<()6:5&>56>*;+76?(6;9(76$<6$'6($)+,69<$8(6&'6<5( %$';=$><;)(6*=6@('&>&++&'A @)*7;><96(#<)$><(7 $&) >**+&'86:$<()6*;< $&)6=&+<() (#5$;9<6+&'( $>&70?$9(6)(9()B*&) %*<*) ';<)&('<9 >**+&'86C$>D(< %&#&'867(B&>( 9$%@+(6<;?( >**+&'86:$<()6&' (a) E5,6&96each *=6<5(6=*++*:&'86>*%@*'('<96(99('<&$+6<*6<5(6@)*>(99F Sterile The fermenter vessel should be sterile and protected by filters from potential contamination Aeration The mixing device, and sterile air moving in increases aeration for growth and improves the contact with nutrients pH Control It may be necessary to control the acidity of the mixture slightly to maintain the optimum pH for growth Temperature Control The cooling jacket, and cooling water and a thermostatically controlled system provide the optimum temperature for growth
  13. 13. Penicillin Production Next After 30 hours, production begins. Penicillin is secreted by the fungus, but only after the exponential phase has ended, when glucose is depleted. This means it is a secondary metabolite. First The Penicillium notatum is added to the fermenter and beings to grow in optimum conditions Time PopulationSize 1 2 3 4 5
  14. 14.