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Explain the term aseptic techniques and sterile conditions and why they are important in microbiology
- Proper aseptic technique prevents contamination of cultures from foreign bacteria inherent in the environment.
- thus interfering with the lab results.
- Essential for isolation of a single species of microorganism from a mixed culture to obtain a pure culture.
- Prevents microbes used in the laboratory from accidentally being released into the environment and/ or infecting people working in the laboratory. This is especially relevant when pathogens are being handled.
Bacterial structure the gram stain is based on
- Gram staining is based on the ability of bacteria cell wall to retaining the crystal violet dye during solvent treatment.
- The cell walls for Gram-positive microorganisms have a higher peptidoglycan and lower lipid content than gram-negative bacteria. Bacteria cell walls are stained by the crystal violet.
- Iodine mordant: to form the crystal violet-iodine complex so that the dye cannot be removed easily.
- +: purple
three differences between gram + and gram _ bacteria
- Gram-positive cell walls contain a thick layer of peptidoglycan that encircles the cell. Gram-negative cell walls contain a thin layer of peptidoglycan between the cytoplasmic membrane and the outer membrane.
- -: presence of outermembrane, high lipid content
key incubation conditions when culturing bacteria
Keep plates at room temperature or incubate at 20-25 °C for 2-3 days.
morphological features of bacteria seen on gram stained slide
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