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Microbiology: Understanding Lactobacillus acidophilus and Culture Media, Study notes of Microbiology

An in-depth exploration of lactobacillus acidophilus, a beneficial microbe found in the human gi tract and vagina. It discusses the probiotic activities of l. Acidophilus, including vitamin k production, reduction of mutagenic enzymes, and enhanced barrier functions. The document also delves into the use of culture media in microbiology, explaining the differences between synthetic and complex media, and the functional types of media such as general, enriched, selective, and differential media. It concludes with a brief overview of light microscopy and its types, resolution, and brightfield illumination.

Typology: Study notes

2022/2023

Uploaded on 04/02/2024

jimrose-aragoncillo
jimrose-aragoncillo 🇵🇭

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Studying Microbes: “Seeing” the Invisible
Lactobacillus acidophilus
-Normal flora in GI tract and vagina
-L. gasseri most common of 6 Lactobacilli in human GI tract
-Produce acids from lactose
-Relatives ferment yogurt, sourdough bread
-Sold as health supplements (probiotics)
Probiotic (health promoting) activities
-Vitamin K production
-reduction in fecal mutagenic enzymes
-macrophage stimulation
-bacteriocin production-enhanced barrier functions
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Studying Microbes: “Seeing” the Invisible Lactobacillus acidophilus

  • Normal flora in GI tract and vagina
  • L. gasseri most common of 6 Lactobacilli in human GI tract
  • Produce acids from lactose
  • Relatives ferment yogurt, sourdough bread
  • Sold as health supplements (probiotics)
  • Probiotic (health promoting) activities
  • Vitamin K production
  • reduction in fecal mutagenic enzymes
  • macrophage stimulation
  • bacteriocin production-enhanced barrier functions

Why might there be more than one microbe in the sample?

Physical State of Media Chemical Content

  • Synthetic : all components known and quantified
  • Complex : some components not known or quantified
    • may contain mixture of partially digested proteins, serum, or RBC Some media components
    • Peptones - protein hydrolysates prepared by partial digestion of various protein sources
    • Extracts - aqueous extracts, usually of beef or yeast
    • Agar - sulfated polysaccharide used to solidify liquid media Functional Types of Media
    • General
    • Enriched
    • Selective
    • Differential

Functional Types of Media

  • general purpose media
    • support the growth of many microorganisms
    • e.g., tryptic soy agar, Nutrient Agar
  • enriched media
    • general purpose media supplemented by blood or other special nutrients
    • e.g., blood agar
    • chocolate agar
  • selective media - favor the growth of some microorganisms and inhibit growth of others
  • Differential media - distinguish between different groups of microorganisms based on their biological characteristics e.g., blood agar

Light microscope

  • The use of any kind of microscope that uses visible light to observe specimens
  • Types of light microscopy
    • Compound light microscopy
    • Darkfield microscopy
    • Phase-contrast microscopy
    • Differential interference contrast microscopy
    • Fluorescence microscopy
    • Confocal microscopy Resolution
  • The ability of the lens to distinguish two points a specified distance apart.
  • The shorter the wavelength, the greater the resolution.
  • Best resolution of light microscopes is 0.2 mm (2,000X) Brightfield Illumination
  • Usual configuration of the light microscope
  • Light passes through the specimen and is seen in the eyepiece
  • Staining gives increased contrast so cells can be seen.