Luria-Bertani Broth, LB media, Powder (Miller's) , 250g
- Product Code: GMNB-LBB115
- Availability: In Stock
LB Broth, culture media
250g, fine powder (Miller's), up to make 10L liquid media.
500g, fine powder (Miller's), up to make 20L liquid media.
LB is a microbial growth medium commonly used for the cultivation of E. coli. This broth contains peptides, amino acids, water-soluble vitamins and carbohydrates. It is suitable for the non-selective culture of E. coli strains for cloning, DNA plasmid preparation and expression of recombinant proteins. It is also suitable for selective cultures when appropriate antibiotics are added.
Our LB media is crafted from premium raw materials. The yeast extract we use is derived from high-quality baking yeast that is completely free from tannic acid contamination — an element that can inhibit bacterial growth, which results in a product that outperforms conventional wine/beer yeast extracts. Additionally, compared to the major competing supplier, we use a superior beef‑sourced tryptone. This ingredient delivers a well-balanced amino acid profile along with essential fatty acids and organic iron, promoting the growth of fastidious bacteria more effectively than vegetable peptone (typically soy peptone), which is often chosen for its lower cost and easier international customs clearance despite its higher lectin content, which also interfere the sensertive bacteria growth. It is suitable for the non-selective culture of E. coli strains for cloning, DNA plasmid preparation and expression of recombinant proteins. It is also suitable for selective cultures when appropriate antibiotics are added.
Components
Sodium chloride 10.0 g/L
Tryptone * 10.0 g/L
Yeast extract (premium) 5.0 g/L
* Vegetable tryptone can be arranged if requested in advance. The price is the same.
Final pH 7.0 ± 0.1 at 25 ℃
Preparation
Suspend 25.0 g of LB Broth (or with Agar for preparing solid media) in distilled water, mix well and make up to 1000 ml.
Sterilise by autoclaving at 121℃ for 15 minutes. Aliquot as needed.
FAQ
Peptone-Based Culture Media Overview
Culture media are specifically formulated nutrient mixtures designed to support the growth and maintenance of microorganisms, plants, and animal tissues. Their composition generally includes water, nitrogen sources, inorganic salts (with trace elements), carbon sources, and essential growth factors such as vitamins, amino acids, nucleotides, antibiotics, pigments, hormones, and serum.
LB Medium Storage Guidelines
The preparation, use, and storage of LB medium vary depending on the raw materials and specific requirements. Culture media are highly susceptible to bacterial contamination or decomposition when exposed to heat or moisture, making proper storage crucial to ensure longevity and integrity.
Powder Form
Since liquid media are difficult to preserve long-term, they are typically converted into powder form and stored in a dry, cool, and light-protected environment.
Refrigeration for Sterile Media: Media requiring strict sterilisation, such as tissue culture media, should be refrigerated at 3–6°C for prolonged storage.
Common Causes of Precipitates in Peptone-Based Culture Media
Weighing Errors Inaccurate measurements due to faulty equipment or miscalculations can lead to improper media concentrations, resulting in precipitation.
Suboptimal Water Quality
The preparation of most media requires purified or deionised water. Using tap or mineral water, or water with residual ions, can cause turbidity or precipitation after sterilisation.
Phosphate-rich media are particularly prone to such issues. Additionally, commercial distilled water may have a slightly lower pH, necessitating pH adjustment to ensure accuracy.
Incorrect pH of the Medium
Media with excessively acidic or alkaline pH can cause precipitation of metal ions.
Ensure the final pH of the LB medium is adjusted to approximately 7.2 before proceeding with microbial culturing.
Contaminated Containers Residual impurities on the surface of new or improperly cleaned containers can introduce unwanted particles or contaminants into sterilised media.
Intrinsic Precipitates in the Medium
Some media, particularly those with high concentrations of inorganic salts or insoluble components, may naturally exhibit precipitation post-sterilization. This is considered normal and does not affect usability. For example, media such as MC, TTB, or BS are known to contain such insoluble elements.
Insufficient Dissolution
Media must be thoroughly mixed and completely dissolved before sterilisation.
Incomplete dissolution can result in flocculent or lumpy precipitates. For instance, Fraser medium, which contains substantial phosphate content, requires complete dissolution pre-sterilization to prevent phosphate clumping.
Improper or Over-Sterilisation
Heat-sensitive media components can degrade during excessive sterilization, resulting in discoloration or precipitation. This is particularly critical for media with high carbohydrate (sugar) content.
For example, properly prepared selenium-cysteine enrichment broth (SC) should appear as a clear, light yellow liquid without sediment; excessive heating could lead to the formation of red precipitates.
Temperature Sensitivity During Additive Incorporation
Additives such as egg yolk or blood are highly sensitive to temperature fluctuations. Incorporating these components at excessively high temperatures or under significant temperature discrepancies may cause coagulation or flocculent precipitation.
Agar Media Preparation:
Agar usually contains a certain amount of agar linate, which is particularly sensitive to metallic ions such as calcium (Ca) and magnesium (Mg), and the quality of agar powder plays a critical role in the outcome.
To evaluate the quality of agar, sterilise the LB medium without agar separately from a 2% agar solution in distilled water. Inspect each for the presence of flocculent substances to identify potential contamination sources.
For consistent results, strict controls during preparation, including pH adjustments and avoiding metallic ion contamination, are essential.
