MicrobiologyLesson 1 of 1 in the course Microbial Biochemistry

Biochemical and Cellular Profiles for Microbial Identification

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Identifying bacteria accurately helps clinicians choose appropriate treatments and supports public health responses to outbreaks. This lesson introduces ways biochemical traits can reveal a microorganism’s identity, including stored cellular products, metabolic reactions, and protein patterns measured by mass spectrometry.

Bacteria differ in the substances they produce, the nutrients they can use, and the chemical reactions they perform. These observable or measurable characteristics are called phenotypic biochemical traits. Comparing an unknown isolate’s traits with known profiles can help determine its genus and species.

All flashcards

What is PHB?
Poly-β-hydroxybutyrate, a carbon- and energy-storage compound that some bacteria accumulate in granules.
What does a Biolog system assess?
It tests multiple metabolic reactions and physiological responses, including responses involving pH and chemical sensitivity.
How does MALDI-TOF support microbial identification?
It produces a mass spectrum from a sample that can be compared with reference spectra.
What happens during FAME analysis?
Extracted microbial fatty acids are converted into volatile methyl esters and analyzed by gas chromatography.
How can serological tests identify microorganisms?
Antibodies or other binding proteins recognize surface carbohydrates; binding may cause detectable cell clumping.

Quiz questions

  1. Which combination of traits can help distinguish species within the genus Pseudomonas?Answer: The presence or absence of PHB granules and fluorescent pigments.
  2. Which information can a Biolog panel use to identify a microorganism?Answer: Its use of selected biochemicals and physiological responses such as pH or chemical sensitivity.
  3. In MALDI-TOF, what influences how long gaseous ions take to travel through the instrument?Answer: Their mass-to-charge ratios.
  4. How does a MALDI-TOF database help identify an unknown microorganism?Answer: It provides known spectra for comparison with the unknown sample's spectrum.
  5. What feature do Lancefield grouping tests use to help identify Streptococcus species?Answer: Distinctive carbohydrates on the cell surface.

Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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