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2× YT Broth (Double-Strength Yeast Tryptone Broth) | High-Yield Bacterial Growth Medium
  • 2× YT Broth (Double-Strength Yeast Tryptone Broth) | High-Yield Bacterial Growth Medium
2× YT Broth

AS-1398

2× YT Broth

$35.00 AUD ex GST
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Dehydrated Culture Medium

Enriched yeast extract–tryptone broth for high-density liquid culture of recombinant Escherichia coli and M13 phage work

Cat. No. AS-139831 g/LpH 7.0 ± 0.2Non-selective brothMolecular biology

At a glance

  • Target organismsE. coli host strains
  • Incubation35–37 °C, aerobic, shaking
  • Time16–24 h
  • Sterilisation121 °C, 15 min
Manufactured in Melbourne. TDS and SDS available. Batch COA on request.

Overview

2× YT Broth (2× Yeast Extract Tryptone Broth) is an enriched, non-selective liquid medium for high-density culture of recombinant Escherichia coli and for M13 bacteriophage work. The name comes from the original YT medium: 2× YT contains twice its tryptone and yeast extract (YT: 8 g/L tryptone, 5 g/L yeast extract).

Compared with LB Broth (Miller), 2× YT Broth has more tryptone (16 vs 10 g/L), twice the yeast extract (10 vs 5 g/L) and half the sodium chloride (5 vs 10 g/L). The richer nutrient base supports denser cultures for plasmid preparation, protein expression and phage production.

Key features

  • Richer than LB: 16 g/L tryptone and 10 g/L yeast extract
  • A standard medium for M13 phage work and phage display hosts such as XL1-Blue and TG1
  • Accepts antibiotics and other heat-labile supplements added after autoclaving

Principle of the Medium

Component Function
Tryptone Peptides, amino acids and nitrogen
Yeast extract B vitamins, nucleotides and growth factors
Sodium chloride Maintains osmotic balance
The medium contains no selective agents. To select plasmid-bearing cells, add antibiotics after autoclaving, once the broth has cooled to room temperature.

Typical Composition

Ingredient g/L
Tryptone 16.00
Yeast extract 10.00
Sodium chloride 5.00
Total 31.00

Final pH 7.0 ± 0.2 at 25 °C. Formula may be adjusted and/or supplemented to meet performance specifications.

Common Antibiotic Concentrations

Antibiotic Typical working concentration
Ampicillin (or carbenicillin) 50–100 µg/mL
Kanamycin 50 µg/mL
Chloramphenicol 25–34 µg/mL
Tetracycline 10–12.5 µg/mL

Applications

Field Typical use
Plasmid preparation Overnight cultures of E. coli for minipreps and midipreps
Protein expression Growth of expression strains such as BL21(DE3) before induction
Phage work Propagation of M13 bacteriophage and amplification of phage display libraries
Teaching laboratories Liquid culture and antibiotic selection practicals

Comparable Products

Manufacturer Product Relationship
HiMedia Laboratories G034 2XYT Growth Medium Same published formulation

Frequently Asked Questions

What is the difference between 2× YT Broth and LB Broth?

2× YT contains 16 g/L tryptone and 10 g/L yeast extract, compared with 10 g/L and 5 g/L in LB (Miller). It also has half the salt (5 vs 10 g/L). The richer formula gives denser cultures.

Why is it called 2× YT?

It contains twice the tryptone and yeast extract of the original YT medium (8 g/L tryptone, 5 g/L yeast extract).

How much powder do I need?

31 g per litre of purified water. A 500 g pack makes about 16 litres.

Can I make plates from it?

Yes. Add 15 g/L agar before autoclaving, or use 2× YT Agar (AS-1395), which is the same formula with agar included.

Intended use: For laboratory microbiological testing, quality control and research use only. Not intended for direct use in food, human or veterinary therapeutic applications, diagnosis, or consumption.

Mode of Action

Tryptone supplies peptides and amino acids, and yeast extract supplies B vitamins, nucleotides and other growth factors. The higher nutrient content than LB supports denser cultures of E. coli. Sodium chloride maintains osmotic balance. The medium is non-selective; selection comes from antibiotics added after autoclaving.

Preparation

  1. Suspend 31 g of powder in 1 litre of purified or distilled water.
  2. Mix well until completely dissolved, warming gently if needed.
  3. Dispense into flasks or tubes. For good aeration, fill flasks to no more than 20–25% of their volume.
  4. Sterilise by autoclaving at 121 °C for 15 minutes.
  5. Cool to room temperature.
  6. Add filter-sterilised antibiotics or other supplements aseptically, if required.
Solid medium: 2× YT Agar (AS-1395) is the same formula with 15 g/L agar (46 g/L).

Incubation and Interpretation

Parameter Condition
Atmosphere Aerobic, with shaking (about 200–250 rpm)
Temperature 35–37 °C
Time 16–24 hours
Positive result Turbidity (growth) in the broth

Growth does not identify an organism or confirm a clone. Confirm transformants by colony PCR, restriction digestion or sequencing as appropriate.

Limitations

  • Non-selective: contaminating organisms will also grow unless antibiotics are added.
  • Antibiotics are heat-labile; add them only after the broth has cooled.
  • Ampicillin is degraded by β-lactamase secreted into the medium during long incubations; carbenicillin is more stable.
  • Growth rate and final density vary between host strains and with aeration.

Literature and References

  1. Sambrook J, Russell DW. Molecular Cloning: A Laboratory Manual, 3rd ed. Cold Spring Harbor Laboratory Press; 2001.
  2. Green MR, Sambrook J. Molecular Cloning: A Laboratory Manual, 4th ed. Cold Spring Harbor Laboratory Press; 2012.
  3. Messing J. New M13 vectors for cloning. Methods Enzymol. 1983;101:20–78.
  4. Barbas CF III, Burton DR, Scott JK, Silverman GJ. Phage Display: A Laboratory Manual. Cold Spring Harbor Laboratory Press; 2001.
  5. Atlas RM. Handbook of Microbiological Media, 4th ed. CRC Press; 2010.

Hazard Identification

Not classified as hazardous according to the GHS (Rev. 7) as adopted in Australia under the model WHS Regulations. Not Dangerous Goods under the ADG Code.

Fine powder can form combustible dust concentrations in air. Dust may cause mild mechanical irritation of the eyes and respiratory tract. Contains casein-derived material: people with milk protein allergy should avoid exposure.

Composition

Ingredient CAS No. % w/w
Tryptone (enzymatic digest of casein) 91079-40-2 51.6
Yeast extract 8013-01-2 32.3
Sodium chloride 7647-14-5 16.1

First Aid

Route Action
Inhalation Move to fresh air. Seek medical advice if symptoms persist.
Skin Wash with soap and water.
Eyes Rinse with water for several minutes. Seek medical advice if irritation persists.
Ingestion Rinse mouth. Do not induce vomiting. Seek medical advice if unwell.
Poisons Information Centre (Australia, 24 h): 13 11 26

Handling, Spills and Disposal

  • Avoid generating and breathing dust. Weigh in a ventilated area.
  • Spills: sweep up or HEPA-vacuum without raising dust; wash the area with water.
  • Unused product: dispose of as non-hazardous waste under local regulations.
  • Inoculated medium: treat as potentially biohazardous and decontaminate (for example by autoclaving) before disposal.

Quality Control Specification

Each batch is tested for growth performance. Aerobic incubation at 35–37 °C for 18–24 hours.

QC organism Strain Inoculum (CFU) Expected result
Escherichia coli ATCC 25922 50–100 (≤ 100) Good to luxuriant
Escherichia coli ATCC 23724 50–100 (≤ 100) Good to luxuriant
Escherichia coli K-12 ATCC 23716 50–100 (≤ 100) Good to luxuriant

Physical and Chemical Tests

Test Specification
Appearance, powder Cream to yellow, homogeneous, free-flowing
Solubility Dissolves completely (31 g/L)
Appearance, prepared medium Light yellow, clear solution
pH, prepared medium (25 °C) 6.80–7.20
The information on this page is provided in good faith as a guide to the properties and use of this product and does not constitute a warranty of fitness for a particular purpose. Users are responsible for confirming suitability for their application. Ausamics Pty Ltd · ABN 56 676 640 467 · 36/25 Trafalgar Road, Epping VIC 3076, Australia · support@ausamics.com

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