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Lysogeny broth

Lysogeny broth is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Lysogeny broth rather than just read about it. In short: Lysogeny broth (LB) is a nutritionally rich medium primarily used for the growth of bacteria. Its creator, Giuseppe Bertani, intended LB to stand for lysogeny broth, but LB has also come to colloquially mean Luria broth, Lennox broth, life broth or Luria–Bertani medium.

Lysogeny broth — main illustration
Lysogeny broth — illustration

Key takeaways

  • Lysogeny broth belongs to biology; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Lysogeny broth to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Lysogeny broth from memory before moving on to harder problems.

Reference excerpt

Lysogeny broth (LB) is a nutritionally rich medium primarily used for the growth of bacteria. Its creator, Giuseppe Bertani, intended LB to stand for lysogeny broth, but LB has also come to colloquially mean Luria broth, Lennox broth, life broth or Luria–Bertani medium. The formula of the LB medium was published in 1951 in the first paper of Bertani on lysogeny. In this article he described the modified single-burst experiment and the isolation of the phages P1, P2, and P3. He had developed the LB medium to optimize Shigella growth and plaque formation. LB medium formulations have been an industry standard for the cultivation of Escherichia coli as far back as the 1950s. These media have been widely used in molecular microbiology applications for the preparation of plasmid DNA and recombinant proteins. It continues to be one of the most common media used for maintaining and cultivating laboratory recombinant strains of Escherichia coli. For physiological studies however, the use of LB medium is discouraged. There are several common formulations of LB. Although they are different, they generally share a somewhat similar composition of ingredients used to promote growth, including the following:

Peptides and casein peptones Vitamins (including B vitamins) Trace elements (e.g. nitrogen, sulfur, magnesium) Minerals Sodium ions for transport and osmotic balance are provided by sodium chloride. Tryptone is used to provide essential amino acids such as peptides and peptones to the growing bacteria, while the yeast extract is used to provide a plethora of organic compounds helpful for bacterial growth. These compounds include vitamins and certain trace elements. In his original 1951 paper, Bertani used 10 grams of NaCl and 1 gram of glucose per 1 L of solution; Luria in his "L broth" of 1957 copied Bertani's original recipe exactly. Recipes published later have typically left out the glucose.

Formula

The formulations generally differ in the amount of sodium chloride, thus providing selection of the appropriate osmotic conditions for the particular bacterial strain and desired culture conditions. The low salt formulations, Lennox and Luria, are ideal for cultures requiring salt-sensitive antibiotics.

LB (Miller) (10 g/L NaCl) LB (Lennox) (5 g/L NaCl) LB (Luria) (0.5 g/L NaCl)

Adjusting the pH Prior to autoclaving, some laboratories adjust the pH of LB to 7.5 or 8 with sodium hydroxide. However, sodium hydroxide does not provide any buffering capacity to the media, and this results in rapid changes to the pH during bacteria cultivation. To get around this some laboratories prefer to adjust the pH with 5–10 mmol/L TRIS buffer, diluted from 1 mol/L TRIS stock at the desired pH. However, it is not absolutely necessary to adjust the pH for most situations. Some laboratories adjust the pH to 7.0 merely as a precaution.

See also Agar plate Salvador Luria Jeffrey H. Miller SOC medium – another widely used medium for culture of Escherichia coli in molecular biology work

References

Illustrations

Lysogeny broth: LB medium bottle and LB agar plate
LB medium bottle and LB agar plate
Lysogeny broth: Plate medium agar LB
Plate medium agar LB
Lysogeny broth: LB medium
LB medium

Worked examples

Example 1 — a first encounter with Lysogeny broth

Start with the simplest possible case. Write down what Lysogeny broth claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Lysogeny broth before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Lysogeny broth ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Lysogeny broth

In research
Lysogeny broth appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Lysogeny broth in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Lysogeny broth is common in secondary-school and first-year university syllabi. It links to neighbouring topics Microbiological media, so understanding it makes those chapters shorter.
In everyday life
Look for Lysogeny broth outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Lysogeny broth in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Lysogeny broth means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Lysogeny broth out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lysogeny broth in simple terms?

Lysogeny broth (LB) is a nutritionally rich medium primarily used for the growth of bacteria. Its creator, Giuseppe Bertani, intended LB to stand for lysogeny broth, but LB has also come to colloquially mean Luria broth, Lennox broth, life broth or Luria–Bertani medium.

Why does Lysogeny broth matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Lysogeny broth?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Lysogeny broth.

Tags

  • Microbiological media

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