Löwenstein-Jensen Medium Base (L.J. Medium): Egg-Based Medium for Mycobacterium Isolation & Cultivation; Cat: AS-1443
$115.00 AUD
Documentation
AuSaMicS Life Science™ · Dehydrated Culture Media · Mycobacteriology & TB Diagnostics
Löwenstein-Jensen Medium Base (L.J. Medium)
Egg-Based Medium for Mycobacterium Isolation & Cultivation | Cat: AS-1443
The gold-standard egg-based selective medium for isolation and cultivation of Mycobacterium species, including M. tuberculosis. This dehydrated base is combined with glycerol and fresh egg suspension, then solidified by inspissation. Australian stock held in Melbourne — same-day dispatch with full COA documentation.
AS-1443 In Stock Australia Same-Day Dispatch Requires Egg Suspension + Inspissation
Quick Specs
CatalogueAS-1443
Base Dissolution37.24 g/L
Final pH~6.8
Coagulation85°C / 45–50 min
ReferenceLöwenstein 1931 / Jensen 1932
Overview
Löwenstein-Jensen (L.J.) Medium is the most widely used egg-based solid medium for isolation and cultivation of Mycobacterium species, and remains a cornerstone of tuberculosis diagnostics worldwide. Originally formulated by Ernst Löwenstein in 1931, the medium was modified by Jensen (1932) into the version in common use today.
This is an egg-based medium: the dehydrated base (AS-1443) provides nutrients, buffers, and the selective malachite green dye, but must be combined with glycerol (or sodium pyruvate for glycerophobic strains) and a fresh whole-egg suspension, then solidified by inspissation — a materially different process from conventional agar media.
Important — this is a base powder, not a ready-to-pour medium. Preparation requires aseptic addition of fresh egg suspension and heat coagulation (inspissation) at 85°C, not standard autoclaving. See the TDS tab for the full preparation protocol before ordering.
Mode of Action
Potato flour and L-asparagine supply carbohydrate and nitrogen for the slow-growing, lipid-rich Mycobacterium cell. Malachite green is the key selective agent, inhibiting most contaminating Gram-positive organisms while permitting acid-fast Mycobacterium growth — and doubles as a built-in pH indicator (blue = Gram-positive contamination, yellow = Gram-negative dye destruction).
Glycerol favours growth of the human-type tubercle bacillus (M. tuberculosis) but inhibits M. bovis, for which sodium pyruvate is substituted. The heat-coagulated egg suspension supplies essential fatty acids and proteins and forms the solid inoculation surface.
Applications
| Application | Notes |
|---|---|
| Primary isolation of M. tuberculosis | Gold-standard solid culture method for TB diagnosis from clinical specimens |
| Isolation of non-tuberculous Mycobacteria (NTM) | Recovery and preliminary characterisation of other Mycobacterium species |
| Niacin testing | Historical substrate for niacin accumulation testing to help distinguish M. tuberculosis |
| Mycobacteriology research | Reference medium in research and susceptibility testing protocols |
Intended use: For laboratory, diagnostic, and research use by appropriately trained and biosafety-accredited personnel only.
Technical Data Sheet Summary
Formula — Dehydrated Base, Per Litre
| Component | g/L | Role |
|---|---|---|
| Potato Flour | 30.000 | Carbohydrate source |
| L-Asparagine | 3.600 | Nitrogen source |
| Monopotassium Phosphate | 2.400 | Buffering agent |
| Magnesium Citrate | 0.600 | Metal ion chelation |
| Magnesium Sulfate | 0.240 | Enzyme cofactor |
| Malachite Green | 0.400 | Selective inhibitor / pH indicator |
Total dehydrated base: 37.24 g/L. Glycerol (12 mL/L) and 1000 mL fresh egg suspension are added separately during preparation — not included in the base powder.
Preparation
| Base Solution | Suspend 37.24 g in 600 mL purified water containing 12 mL glycerol (omit for glycerophobic strains — use sodium pyruvate instead). Heat to dissolve. |
| Base Sterilisation | Autoclave at 121°C for 15 minutes. Cool to 50–60°C. |
| Egg Suspension | Prepare 1000 mL fresh whole-egg suspension aseptically. Mix with the cooled sterile base, avoiding air bubbles. |
| Coagulation | Distribute into slanted tubes. Inspissate at 85°C for 45–50 minutes — do not autoclave the egg-containing mixture. |
Incubation
| Temperature / Atmosphere | 35–37°C, 5–10% CO₂ recommended |
| Duration | Up to 8 weeks — M. tuberculosis is slow-growing |
| Positive Result | Non-pigmented, rough, dry, buff/cream colonies |
Contains malachite green — recognised as toxic to aquatic life. Full 16-section SDS is available with detailed handling, environmental, and biosafety guidance.
Safety Data Sheet Summary
| GHS Classification | Base powder: not acutely hazardous to human health; contains malachite green — precautionary environmental hazard classification (H411, toxic to aquatic life) |
| Signal Word | WARNING (environmental) |
| Biosafety Note | Once reconstituted and inoculated, treat as potentially biohazardous — handle under appropriate PC2/PC3 containment per institutional Mycobacterium protocols |
| Environmental | Do not discharge to drains or waterways — malachite green is toxic to aquatic organisms |
| Transport | Not classified as Dangerous Goods (ADG, IATA, IMDG) for the base powder |
Full 16-section GHS-compliant SDS is available as a downloadable document — contact support@ausamics.com quoting catalogue number AS-1443.
Certificate of Analysis
Each batch of L.J. Medium Base (AS-1443) is released with a batch-specific Certificate of Analysis for the dehydrated base powder.
| Test Parameter | Specification |
|---|---|
| Dehydrated Appearance | Pale green, free-flowing powder |
| Prepared Appearance | Pale bluish-green, opaque, coagulated solid slant (with egg suspension) |
| Final pH | Approximately 6.8 (typical range 6.4–7.0) |
| Productivity Test | Mycobacterium tuberculosis H37Rv ATCC 27294 — typical colony growth |
| Selectivity Test | Staphylococcus aureus ATCC 25923 — inhibited |
Note: As this is a base powder requiring aseptic addition of fresh egg suspension by the end user, final medium performance also depends on egg suspension quality and preparation technique.
Batch-specific COA is issued with every shipment. Contact support@ausamics.com quoting catalogue number AS-1443.