In a microbiology lab experiment, two different E. coli strains as a well as a untreated water...


In a microbiology lab experiment, two different E. coli strains as a well as a untreated water sample were plated on an nutrient agar dish using aseptic techniques. The same bacterial solutions were plated on another nutrient agar dish, however this dish was treated with X-gal. What is the purpose of the agar dish not treated with X-gal? (X-gal shows the presence of an enzyme that metabolizes it, which yields a blue color).

Microbiological Analyses:

Microbiology relates to an overall analysis of microbial life, including its positive and negative aspects. The subject often employs an interdisciplinary amalgamation of other scientific studies such as molecular biology, enzymology, proteomics, zoology, and botany.

Answer and Explanation: 1

X-gal is an essential tool for the molecular identification of bacterial species. An important enzyme, beta-galactosidase, hydrolyses this compound, resulting in a blue color to the colonies that have the hydrolyzing capacity. This technique would determine the bacteria that have a functional beta-galactosidase enzyme and those that do not.

The untreated media plate will act as a control to distinguish among the E.coli strains if they can express the enzyme beta-galactosidase or not and would tell about the species if they are lactose tolerant or not.

Learn more about this topic:

Escherichia coli (E. coli) as a Model Organism or Host Cell


Chapter 6 / Lesson 16

Escherichia coli, better known as E. coli, is a mammalian gut bacteria frequently used by scientists as a model organism or host cell to research biological phenomena with the intention of applying discoveries to other biological species. Explore the past and present of E.coli outbreaks, implications of genetic manipulation, and how model organisms assist with biological research.

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