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SOC Medium | High-Efficiency Transformation Recovery Broth
$35.00 AUD
SOC Medium
Super Optimal broth with Catabolite repression — the gold standard recovery medium for high-efficiency bacterial transformation. Manufactured in Australia with full batch documentation.
AS-1428
Catalog No.
AS-1428
Form
Dehydrated powder
Final pH
7.0 ± 0.2 at 25 °C
Reconstitution
28.08 g / 980 mL
Glucose
20 mL of 20% added post-autoclave
HS Code
3821.00
Overview
SOC Medium (Super Optimal broth with Catabolite repression) is the industry-standard recovery medium for bacterial transformation in molecular biology. Originally described by Hanahan (1983), SOC is a nutrient-rich broth that maximises the metabolic recovery of competent bacterial cells following heat-shock or electroporation, dramatically increasing transformation efficiency compared to simpler media such as LB or SOB.
AuSaMicS AS-1428 is supplied as a dehydrated powder base containing all components except glucose, which is added aseptically after autoclaving to prevent Maillard reaction browning and nutrient degradation. The formulation is standardised for consistent performance across transformation, cloning, and competent cell preparation workflows.
Composition (per litre of prepared medium)
| Ingredient | g/L | Function | Mechanism |
|---|---|---|---|
| Casein enzymic hydrolysate | 20.0 | Primary nitrogen & amino acid source | Enzymatic digest of casein providing free amino acids and short peptides; rapidly assimilated by recovering cells post-transformation; supports fast resumption of protein synthesis essential for antibiotic resistance gene expression |
| Yeast extract | 5.0 | Vitamins, cofactors & nucleotide precursors | Provides B-group vitamins, nucleotide bases, and trace minerals from autolysed yeast; accelerates DNA repair and replication machinery reactivation in heat-shocked or electroporated cells |
| Sodium chloride | 0.5 | Osmotic balance | Maintains physiological ionic strength; low concentration (0.5 g/L vs 10 g/L in LB) reduces osmotic stress on fragile post-transformation cells and enhances plasmid uptake efficiency |
| Potassium chloride | 0.186 | Ionic supplement | Provides K⁺ ions critical for membrane potential maintenance and active transport recovery; supports resumption of nutrient import in recovering cells |
| Magnesium sulphate | 2.4 | Divalent cation source | Mg²⁺ is essential cofactor for DNA polymerase, RNA polymerase, and ribosome assembly; stabilises cell membranes post-transformation; replaces Mg²⁺ lost during heat shock; MgSO₄ preferred over MgCl₂ for reduced chloride load |
| Glucose (added post-autoclave) | ~3.6 (from 20 mL of 20% solution) | Carbon source & catabolite repressor | Rapidly fermentable carbon source restoring ATP production in recovering cells; catabolite repression by glucose suppresses expression of catabolic genes, redirecting cellular energy to plasmid replication and resistance gene expression; added post-autoclave to prevent Maillard browning and glucose degradation |
| Final pH: 7.0 ± 0.2 at 25 °C — Neutral pH optimises enzyme activity and matches physiological conditions of E. coli and related enteric bacteria during recovery phase | |||
Applications
Bacterial transformationRecovery medium after heat-shock or electroporation of competent E. coli — DH5α, TOP10, BL21, DH10B, and similar strains
Cloning workflowsPost-ligation transformation recovery for subcloning, Gibson Assembly, Golden Gate, and TOPO cloning
Electroporation recoveryHigh-efficiency recovery after electroporation of bacterial and yeast cells requiring rapid metabolic restoration
Competent cell preparationPre-transformation growth medium for preparation of chemically competent or electrocompetent cells
Library constructionMaximises colony number in genomic and cDNA library construction where transformation efficiency is critical
Recombinant protein expressionInitial recovery medium before transfer to expression media; ensures maximum viable cell count post-transformation
Strengths & Limitations
Strengths
Maximises transformation efficiency — consistently outperforms LB and SOB in colony yield
Low NaCl (0.5 g/L) reduces osmotic stress on fragile post-transformation cells
Glucose catabolite repression enhances plasmid stability and resistance gene expression during recovery
Dehydrated format — long shelf life, no refrigeration of base powder required
Standardised formulation — batch-to-batch consistency for reproducible transformation results
Australian-made with full documentation (COA, TDS, SDS) per batch
Limitations
Requires aseptic glucose addition post-autoclave — one additional preparation step vs ready-to-use liquid media
Not suitable for routine bacterial cultivation — cost is higher than LB or NB for non-transformation applications
Glucose concentration critical — excess glucose can cause rapid acidification in dense cultures
Not recommended for yeast transformation recovery — use YPD or SC media instead
Comparative Media — Bacterial Transformation & Molecular Biology
| Medium | NaCl (g/L) | Glucose | Mg²⁺ | Primary use | Transformation efficiency | AuSaMicS Cat. |
|---|---|---|---|---|---|---|
| SOC Medium — AS-1428 | 0.5 | Yes (post-autoclave) | Yes (2.4 g/L) | Transformation recovery — gold standard | Highest | AS-1428 |
| SOB Medium | 0.5 | No | Yes | Competent cell preparation, pre-transformation growth | High | AS-1427 |
| LB Broth (Lennox) | 5.0 | No | No | General E. coli cultivation, routine cloning | Moderate | AS-1271 |
| Terrific Broth (TB) | — | No | No | High-density culture, recombinant protein expression | Moderate | AS-1380 |
| 2×YT Broth | 5.0 | No | No | Phage display, antibody library construction | Moderate | AS-1400 |
| Nutrient Broth | 5.0 | No | No | General bacteriology, maintenance cultures | Low | AS-1310 |
Cross-Reference / Equivalent Products
AS-1428 is equivalent to the following products from major international suppliers:
| Supplier | Product Name | Catalogue Number |
|---|---|---|
| Oxoid (Thermo Fisher) | SOC Medium | CM1375 |
| BD Difco | SOC Medium | 244510 |
| Merck (Sigma-Aldrich) | SOC Medium | S1797 |
| Thermo Fisher Scientific | SOC Medium | 15544034 |
| AuSaMicS | SOC Medium | AS-1428 |
Preparation Instructions
1. Weigh: Suspend 28.08 g of AS-1428 dehydrated powder in 980 mL of distilled or deionised water.
2. Mix: Stir to dissolve. Heat gently if required. The broth should appear clear to slightly opalescent and pale yellow.
3. Autoclave: Sterilise at 121 °C for 15 minutes (15 psi / 103 kPa).
4. Cool: Allow to cool to 45–50 °C before glucose addition.
5. Add glucose: Aseptically add 20 mL of filter-sterilised 20% (w/v) glucose solution (prepared separately and sterilised by 0.2 µm filtration — do not autoclave glucose). Mix gently.
6. Dispense: Distribute into sterile tubes or flasks under aseptic conditions. Final volume = 1 litre.
Storage of prepared SOC: Store at 2–8 °C for up to 3 months. Discard if turbidity, precipitation, or colour change is observed prior to use.
2. Mix: Stir to dissolve. Heat gently if required. The broth should appear clear to slightly opalescent and pale yellow.
3. Autoclave: Sterilise at 121 °C for 15 minutes (15 psi / 103 kPa).
4. Cool: Allow to cool to 45–50 °C before glucose addition.
5. Add glucose: Aseptically add 20 mL of filter-sterilised 20% (w/v) glucose solution (prepared separately and sterilised by 0.2 µm filtration — do not autoclave glucose). Mix gently.
6. Dispense: Distribute into sterile tubes or flasks under aseptic conditions. Final volume = 1 litre.
Storage of prepared SOC: Store at 2–8 °C for up to 3 months. Discard if turbidity, precipitation, or colour change is observed prior to use.
⚠️ Critical: Do NOT autoclave glucose together with the base medium. Glucose degrades and undergoes Maillard reactions at autoclave temperatures, causing browning, nutrient destruction, and reduced transformation efficiency. Always add filter-sterilised glucose separately after cooling.
Frequently Asked Questions
Q1: Why is glucose added after autoclaving and not included in the base powder?
Glucose undergoes Maillard (browning) reactions with amino acids at autoclave temperatures (121 °C), which degrades nutrients, reduces medium clarity, and significantly impairs transformation efficiency. Glucose is therefore always added aseptically after autoclaving as a filter-sterilised 20% (w/v) solution.
Q2: What is the difference between SOC and SOB medium?
SOB (Super Optimal Broth) is the base medium without glucose — identical in composition to SOC except no glucose is added. SOB is used for growing cells prior to making them competent. SOC is SOB with glucose added post-autoclave, used specifically for the recovery step after transformation to maximise transformation efficiency via catabolite repression.
Q3: Which E. coli strains are compatible with SOC medium?
SOC is compatible with all standard laboratory E. coli strains including DH5α, DH10B, TOP10, BL21(DE3), XL1-Blue, JM109, and most recombinant and competent cell strains. It is the recommended recovery medium in protocols from NEB, Invitrogen, Thermo Fisher, and most major cloning kit manufacturers.
Q4: How does SOC improve transformation efficiency compared to LB?
SOC improves transformation efficiency through three mechanisms: (1) low NaCl (0.5 g/L vs 10 g/L in LB) reduces osmotic stress on fragile post-transformation cells; (2) Mg²⁺ ions stabilise cell membranes and support DNA repair machinery; (3) glucose catabolite repression suppresses catabolic gene expression, redirecting cellular energy to plasmid replication and antibiotic resistance gene expression during the critical recovery window. Transformation efficiencies with SOC are typically 5–10× higher than with LB.
Q5: What is the HS tariff code for SOC Medium?
HS Code 3821.00 — prepared culture media for development or maintenance of microorganisms.
Important Notice: For laboratory and research use only. Not for human consumption, veterinary, food, or household use. By purchasing, the buyer confirms compliance with all applicable Australian laws, institutional biosafety requirements, and workplace health and safety regulations. AuSaMicS Pty Ltd accepts no liability for misuse outside a controlled laboratory environment.
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Technical Data Sheet — AS-1428 SOC Medium
Document Type
Technical Data Sheet
Product
SOC Medium
Catalog No.
AS-1428
Revision
1.0
Issuer
AuSaMicS Pty Ltd
Technical Overview & Biochemistry
SOC Medium is a nutrient-rich bacterial recovery broth originally formulated by Hanahan (1983) to maximise the survival and metabolic recovery of bacterium cells following transformation procedures. The medium combines a rich amino acid and peptide source (casein hydrolysate), vitamin and nucleotide precursor supply (yeast extract), precise ionic conditions (low NaCl, KCl, MgSO₄), and post-autoclave glucose to deliver the optimal biochemical environment for recovering transformed cells.
The critical innovation of SOC over earlier media (SOB, LB) is the addition of glucose at a concentration sufficient to trigger catabolite repression — the global regulatory mechanism by which E. coli preferentially utilises glucose over other carbon sources, suppressing expression of hundreds of catabolic genes and freeing cellular resources for plasmid replication, resistance gene expression, and cell membrane repair during the recovery period.
Physical & Chemical Properties
| Parameter | Specification |
|---|---|
| Appearance (dehydrated powder) | Cream to pale yellow, homogeneous, free-flowing powder |
| Appearance (prepared broth, before glucose) | Clear to slightly opalescent, pale yellow solution |
| Appearance (prepared broth, after glucose) | Clear to slightly opalescent, pale yellow — no turbidity |
| pH (prepared medium at 25 °C) | 7.0 ± 0.2 |
| Reconstitution rate (base powder) | 28.08 g per 980 mL distilled water |
| Glucose addition | 20 mL of filter-sterilised 20% (w/v) glucose, added post-autoclave at 45–50 °C |
| Final volume | 1,000 mL |
| Sterilisation | Autoclave at 121 °C, 15 min (15 psi); glucose by 0.2 µm filtration only |
| Moisture content (powder) | ≤6% |
| HS Tariff Code | 3821.00 |
Detailed Composition (per litre, final prepared medium)
| Ingredient | g/L | Function | Mechanism |
|---|---|---|---|
| Casein enzymic hydrolysate | 20.0 | Amino acid & nitrogen source | Pancreatic digest providing free amino acids and di/tripeptides; immediate substrate for protein biosynthesis resumption; critical for rapid expression of newly acquired antibiotic resistance genes post-transformation |
| Yeast extract | 5.0 | Vitamins, cofactors, nucleotide bases | Autolysate providing B-vitamins (thiamine, riboflavin, niacin, B6, B12), purine and pyrimidine bases, and trace minerals; supports DNA replication, repair, and RNA synthesis during recovery |
| Sodium chloride | 0.5 | Osmolyte — minimal ionic strength | Deliberately low (10× less than LB) to minimise osmotic stress on cells with transiently compromised membrane integrity post-heat shock or electroporation |
| Potassium chloride | 0.186 | Ionic supplement | K⁺ essential for membrane potential (Nernst equation); supports nutrient import and ATP-dependent recovery processes |
| Magnesium sulphate | 2.4 | Divalent cation — enzyme cofactor & membrane stabiliser | Mg²⁺ cofactor for DNA/RNA polymerases, ribosomes, and ATP; stabilises outer membrane LPS and cell membrane post-heat shock; sulphate form reduces total chloride load compared to MgCl₂ |
| Glucose (filter-sterilised, added post-autoclave) | ~3.6 | Carbon source & catabolite repressor | Drives catabolite repression via cAMP-CRP regulatory system; redirects metabolic flux to glycolysis and anabolism; suppresses sigma factor competition; enhances plasmid copy number stabilisation during recovery window (typically 37 °C, 45–60 min) |
Mode of Action — Why SOC Outperforms LB for Transformation Recovery
Following heat shock (42 °C, 30–90 seconds) or electroporation, bacterial cell membranes are transiently permeabilised, intracellular ATP is depleted, and DNA repair and replication machinery is disrupted. SOC addresses each of these stresses simultaneously: low NaCl minimises osmotic burden during membrane resealing; Mg²⁺ stabilises membrane structure and restores polymerase function; casein hydrolysate provides immediate substrates for resistance gene translation; and glucose rapidly restores ATP production via glycolysis while catabolite repression ensures cellular resources are directed to plasmid maintenance rather than catabolic pathway induction. The combined effect typically yields 5–10× higher transformation efficiency than LB at equivalent cell densities.
Quality Control — Performance Test Organisms
| Organism | ATCC / Reference | Inoculum (CFU) | Incubation | Expected Result | Status |
|---|---|---|---|---|---|
| Escherichia coli DH5α (post-transformation) | ATCC 53868 | ≤100 CFU | 37 °C, 60 min (recovery), then plate | Good recovery; transformation efficiency ≥ reference SOC lot | PASS |
| Escherichia coli K-12 | ATCC 10798 | ≤100 CFU | 37 °C, 48 h | Good growth; turbid broth | PASS |
| Sterility check (uninoculated) | — | — | 37 °C, 48 h | No growth / no turbidity | PASS |
Literature & References
- Hanahan, D. (1983). Studies on transformation of Escherichia coli with plasmids. Journal of Molecular Biology, 166(4), 557–580.
- Sambrook, J. & Russell, D.W. (2001). Molecular Cloning: A Laboratory Manual, 3rd edn. Cold Spring Harbor Laboratory Press. Appendix 1 — Media recipes.
- Green, M.R. & Sambrook, J. (2012). Molecular Cloning: A Laboratory Manual, 4th edn. Cold Spring Harbor Laboratory Press.
- Inoue, H., Nojima, H. & Okayama, H. (1990). High efficiency transformation of Escherichia coli with plasmids. Gene, 96(1), 23–28.
- Görke, B. & Stülke, J. (2008). Carbon catabolite repression in bacteria: many ways to make the most out of nutrients. Nature Reviews Microbiology, 6(8), 613–624.
Download TDS Document
AuSaMicS Pty Ltd Disclaimer: Technical data is based on current literature and internal quality testing. Values may vary by lot. For laboratory use only. Not for human, veterinary, or diagnostic use.
Safety Data Sheet — AS-1428 SOC Medium
Full 16-section Safety Data Sheet compliant with the Globally Harmonised System (GHS) and Australian Work Health and Safety (WHS) Regulations. Download the complete SDS before handling this product.
GHS Standard
GHS Rev. 9
WHS Compliance
Australian WHS Reg. 2017
Sections
16 mandatory
Signal Word
Not classified
SDS Section Summary
| Section | Heading | Key Information |
|---|---|---|
| 1 | Identification | SOC Medium, AS-1428, AuSaMicS Pty Ltd, support@ausamics.com, +61 412 520 598 |
| 2 | Hazard identification | Not classified as hazardous under GHS. No signal word required. Dust may cause mild respiratory irritation. |
| 3 | Composition / ingredients | Casein enzymic hydrolysate, Yeast extract, NaCl, KCl, MgSO₄ — all non-hazardous biological/food-grade materials |
| 4 | First aid measures | Inhalation: fresh air. Skin/eyes: wash with water 15 min. Ingestion: rinse mouth; seek advice if unwell. |
| 5 | Firefighting measures | Not flammable. CO₂ or dry powder extinguisher. SCBA in enclosed fire. |
| 6 | Accidental release | Sweep up powder; avoid generating dust. Prepared broth: absorb with inert material; dispose per local regulations. |
| 7 | Handling & storage | Store powder at 2–25 °C, sealed, dry. Prepared medium at 2–8 °C. Protect from moisture contamination. |
| 8 | Exposure controls / PPE | Lab coat, nitrile gloves, safety glasses. No respiratory protection required for normal handling. |
| 9 | Physical & chemical properties | Cream powder (dry); pale yellow clear liquid (prepared). Not flammable. pH 7.0 prepared. |
| 10 | Stability & reactivity | Stable. Incompatible with strong oxidisers. No hazardous decomposition under normal conditions. |
| 11 | Toxicological information | Not acutely toxic. Low oral, dermal, and inhalation toxicity for all components. |
| 12 | Ecological information | Biodegradable. Not classified as environmentally hazardous. Avoid large releases to waterways (high BOD from protein content). |
| 13 | Disposal | Autoclave inoculated broth before disposal. Uninoculated prepared broth: dilute and drain. Dry powder: general laboratory waste. |
| 14 | Transport information | Not classified as dangerous goods (UN/ADG). No special transport requirements. |
| 15 | Regulatory information | Not subject to AICIS notification. Complies with Australian WHS model regulations. |
| 16 | Other information | Issued by AuSaMicS Pty Ltd. For laboratory use only. Refer to full SDS for complete details. |
Download Full SDS (16-Section, GHS-Compliant)
AuSaMicS Pty Ltd Safety Disclaimer: Always consult the full 16-section SDS before handling. Use appropriate PPE. Emergency contact: +61 412 520 598. AuSaMicS Pty Ltd accepts no liability for injuries resulting from failure to observe standard laboratory safety procedures.
Certificate of Analysis — AS-1428 SOC Medium
A batch-specific Certificate of Analysis is issued for every production lot of AS-1428. The COA confirms that the supplied lot has been tested against all specifications below. Retain your COA for laboratory audit and accreditation purposes.
Issued by
AuSaMicS Pty Ltd
Test frequency
Every production lot
Traceability
LOT & EXP on label
Dispatch
Included with order
Specification Table
| Test Parameter | Method | Specification | Typical Result | Status |
|---|---|---|---|---|
| Appearance (powder) | Visual | Cream to pale yellow, free-flowing, homogeneous | Pale yellow, homogeneous | PASS |
| Appearance (prepared, before glucose) | Visual | Clear to slightly opalescent, pale yellow | Clear, pale yellow | PASS |
| pH (prepared at 25 °C, before glucose) | Potentiometry | 7.0 ± 0.2 | 7.0 | PASS |
| Moisture content | Loss on drying | ≤6.0% | 3.8% | PASS |
| Growth promotion — E. coli K-12 ATCC 10798 | Turbidity / incubation | Good growth ≥ reference lot | Good; turbid broth at 37 °C / 18 h | PASS |
| Transformation efficiency — E. coli DH5α | Transformation assay with pUC19 | ≥ 1 × 10⁶ cfu/µg DNA | ≥ 1 × 10⁶ cfu/µg | PASS |
| Sterility (prepared medium) | Incubation 37 °C / 48 h | No growth | No growth | PASS |
Download Sample COA
AuSaMicS Pty Ltd COA Disclaimer: This Certificate of Analysis is lot-specific. The sample COA shown is representative only. The actual COA for the supplied lot is included with every order. Results are valid for the tested lot under stated storage conditions. For lot-specific documentation: support@ausamics.com.