MacConkey Agar (EP) - BioReagent

Cat. No.: M1528429

QUALITÄT & REINHEIT BioReagent

Storage

Room temperature

Shipped In

Normal

Übersicht

For coliform determination. Preparation method: Weigh 50.0 g of this product in 1 L of distilled or deionized water (the volume may be scaled up or down proportionally), heat to boiling until completely dissolved, dispense, autoclave at 121°C for 15 minutes. After sterilization, shake well to prevent agar from settling and solidifying at the bottom of the vessel, then set aside for use.

Spezifikationen

Spezifikationen & Reinheit

BioReagent

Storage

Room temperature

Verschickt in

Normal

Note

BioReagent

Product Line

Biologische Produkte

Application Protocols

The following is a typical literature protocol for dehydrated MacConkey Agar. It is provided for general guidance and is not item‑specific. Always validate and follow your institution’s SOPs.

Preparation (literature example):

1. Weigh the dehydrated medium according to the supplier’s recommended concentration (commonly around 50 g per liter of water; check CoA/Spec Sheet for the exact value for this item).
2. Add to purified water with vigorous stirring to disperse. Allow to hydrate for several minutes.
3. Heat to boiling with frequent agitation until the agar is completely dissolved and the solution appears uniform.
4. Adjust volume with water if needed. Do not overheat to avoid lactose degradation.
5. Sterilize by autoclaving at 121 °C for 15 minutes (liquid cycle). Loosen caps to prevent vessel deformation.
6. Cool to 45–50 °C in a water bath. Mix gently to homogenize dyes.
7. Pour into sterile plates (≈20–25 mL per 90 mm plate) and allow to solidify. Dry plates at room temperature with lids ajar in a biosafety cabinet if excessive surface moisture is present.
8. Store poured plates inverted in sealed sleeves at 2–8 °C if not used immediately; warm to room temperature before use (verify shelf life per internal QC).

Quality control (literature): Perform growth promotion/selectivity tests with reference strains (one lactose‑positive, one lactose‑negative, and one Gram‑positive for inhibition). Record colony color and morphology after 18–24 h at 35–37 °C.

Biological Roles

MacConkey Agar (EP) functions as a selective and differential environment that probes fundamental microbial physiology.

Biological basis (literature/general):

• Bile tolerance: Enteric Gram‑negative bacteria possess outer membranes and efflux mechanisms that confer resistance to bile salts; Gram‑positives typically exhibit compromised cell wall integrity in their presence, enabling selectivity.
• Lactose metabolism: Fermentation by organisms with β‑galactosidase and permease systems produces acids (e.g., lactic, acetic), dropping local pH.
• pH indication: Neutral red is yellow/orange at neutral to alkaline pH and becomes red/pink upon protonation at acidic pH near fermenting colonies, providing differentiation.
• Precipitation of bile: Acid diffusion around lactose fermenters can precipitate bile salts, forming a halo that further accentuates phenotype.
• Crystal violet interaction: Crystal violet interferes with peptidoglycan assembly, disproportionately affecting Gram‑positive organisms, sharpening selectivity.

Use contexts:

• Characterization of coliforms/Enterobacteriaceae and related Gram‑negative rods from mixed microbiota.
• Microbiological QC to verify absence/presence of bile‑tolerant Gram‑negative organisms in products and process waters.

Note: Biological roles describe how organisms respond to the medium’s components; they are not therapeutic or clinical claims. Actual performance must be demonstrated with growth promotion and suitability tests under your laboratory’s conditions.

Buffer Applications

Not typically applicable. MacConkey Agar is a selective/differential culture medium and is not used as a biochemical buffer system.

Practical note (literature/general): The prepared medium exhibits a controlled pH near neutrality post‑sterilization to support enteric bacteria and enable dye responsiveness, but it is not intended for buffering biochemical reactions or electrophoresis. For buffering needs, select dedicated buffer systems (e.g., phosphate, Tris, MOPS) appropriate to your application.

Green Alternatives

While MacConkey Agar itself does not have a direct “green” substitute in the sense of organic solvents, sustainability considerations apply to media use and waste handling.

Greener practice considerations (general):

• Ready‑to‑use plates vs dehydrated media:
  • Dehydrated media minimize cold‑chain and reduce plastic footprint compared to pre‑poured plates but require autoclave energy. Evaluate total lifecycle in your facility.
• Dye load and disposal:
  • Neutral red and crystal violet contribute to colored wastewater. Implement segregated collection of dye‑containing liquid waste and use approved treatment before drain disposal per local regulations.
• Agar sourcing:
  • Consider suppliers with responsible seaweed harvesting and documented supply chain sustainability for agar.
• Energy and water efficiency:
  • Optimize autoclave loads, use insulated flasks to reduce heat loss, and prepare only the media volume required to limit waste.
• Alternatives for certain workflows (application‑dependent, literature):
  • For lactose fermentation screening with lower dye load, some labs employ chromogenic agars with targeted substrates—these may reduce false positives/negatives but can carry different environmental profiles and costs.
  • For non‑selective pre‑enrichment to reduce selective medium volume, use minimal media (e.g., buffered peptone water) to decrease dye use, followed by targeted plating.

Trade‑offs: Increased selectivity/differentiation often entails additional chemicals (dyes/indicators). Balance analytical performance with waste minimization and regulatory compliance.

Pharmaceutical Uses

No therapeutic use. For research and quality control only.

Pharmacopeial/industrial context (literature/general):

• MacConkey Agar is widely employed in compendial microbiological testing (e.g., European Pharmacopoeia, United States Pharmacopeia) for detection, isolation, and enumeration of bile‑tolerant Gram‑negative bacteria in non‑sterile products, water, and environmental monitoring.
• Typical roles in pharma QC and manufacturing:
  • Growth promotion and inhibition testing to qualify media performance prior to routine use.
  • Suitability tests for microbial limit and specified microorganism assays, often alongside non‑selective media to demonstrate recovery of stressed organisms.
  • Use in environmental monitoring programs (EM) to trend Gram‑negative contaminants in cleanrooms and utilities (air, surfaces, personnel).
• Documentation: Maintain CoAs, lot traceability, and media qualification records. For regulated environments, verify that prepared plates meet EP/USP performance criteria with defined challenge strains under your SOPs.

Item-specific pharmacopeial certifications/claims: Not specified for this item; refer to CoA/Spec Sheet. Research Use Note: For research use only.

Physical Properties

MacConkey Agar (EP) is supplied as a dehydrated powder blend (reconstituted in water to prepare plates or broths). As a complex mixture, discrete physicochemical constants are not defined for the product as a whole.

Item-specific values: Not specified for this item; refer to CoA/Spec Sheet.

General/literature properties of the prepared medium (informational only):

• Physical state (dry): free-flowing heterogeneous powder; color typically pink‑beige to red due to neutral red/crystal violet dyes (supplier dependent).
• Aqueous solubility (components): readily dispersible in purified water; agar forms a sol upon heating and gel upon cooling (thermoreversible gelation typically sets around 35–40 °C; melts near 85–95 °C depending on agar grade; literature ranges).
• pH (at 25 °C, prepared medium): typically ~7.1 ± 0.2 (literature, after autoclaving; exact control varies by standard/spec).
• Ionic strength/osmolality: governed by NaCl and peptones; mixture dependent (no single value).
• Optical properties: selective/differential dyes impart red coloration; lactose fermentation lowers local pH, shifting neutral red to the pink/red protonated form around colonies.
• Density/RI/LogP/pKa: Not applicable for the composite medium.

Handling notes (general): Dissolution is aided by gradual addition to room‑temperature water with vigorous stirring, followed by heating to boil to fully dissolve agar prior to sterilization (details in Application Protocols; literature guidance).

Quality and Grades

• Grade: BioReagent — indicates suitability for biological research workflows (culture media preparation, microbiological QC). While not a GMP grade, BioReagent material is typically produced with attention to bioburden and lot-to-lot performance relevant to laboratory research. Item-specific acceptance criteria are Not specified for this item; refer to CoA/Spec Sheet.
• EP designation: The “(EP)” tag indicates alignment with European Pharmacopoeia context for culture media used in compendial microbiological tests (e.g., selectivity, productivity, and specificity criteria). Note that final compliance is demonstrated by performance testing of the prepared medium per EP chapters (e.g., 2.6.x), not by chemical assay alone.
• What to expect in a high-quality MacConkey Agar (general):
  • Consistent colony morphology/color development for reference strains (e.g., lactose positive E. coli vs lactose negative Salmonella; literature examples), with defined inhibition of Gram-positive controls.
  • Controlled final pH after sterilization and acceptable gel strength/clarity.
  • Low background fluorescence/absorbance that could interfere with imaging or automated colony counters.
• Documentation: Request and review the CoA for each lot for performance parameters (growth promotion, selectivity/suppression, pH, gel strength). If required for regulated work, verify against internal validation or pharmacopeial suitability tests.
• Stabilizers/additives: Not specified for this item; refer to CoA/Spec Sheet.
• UV cutoff/metal limits/peroxide ppm/water ppm: Not specified for this item; refer to CoA/Spec Sheet.

Reaction and Applications

This product is not used as a reagent in chemical synthesis. Its applications are microbiological.

Key applications (literature/general):

• Selective isolation of Gram‑negative enteric bacteria from clinical, food, environmental, or industrial samples; bile salts and crystal violet inhibit many Gram‑positive organisms.
• Differential identification based on lactose fermentation:
  • Lactose‑positive organisms (e.g., many coliforms) produce acid, turning colonies pink/red (neutral red indicator) often with bile precipitation halos.
  • Lactose‑negative organisms (e.g., Salmonella, Shigella) form colorless/pale colonies.
• Quality control (QC) testing in pharmaceutical, cosmetic, and water industries: commonly used in compendial methods (e.g., EP/USP) to assess presence/absence or enumeration of bile‑tolerant Gram‑negative bacteria.
• Environmental monitoring: Surface, hygiene, and process water testing.

Practical tips:

• Thoroughly dissolve and sterilize medium; incomplete agar dissolution yields weak gels and uneven colony morphology.
• Avoid overheating or prolonged autoclaving, which can caramelize lactose and diminish differential performance.
• For heavily contaminated samples, consider pre‑enrichment or parallel plating on non‑selective media to recover stressed organisms.
• Validate against reference strains and perform routine growth promotion testing to verify lot performance in your system (incubators, water quality, sterilization cycle).

Reaction Conditions

Conventional reaction conditions are not applicable. The relevant operational parameters are microbiological culture conditions (literature/general guidance):

• Medium preparation: Reconstitute the dehydrated medium in purified water, heat to dissolve agar, and sterilize by autoclaving (typical details in Application Protocols section).
• Pouring temperature: Cool to approximately 45–50 °C before pouring plates to prevent excessive condensation and preserve indicator integrity.
• Incubation: 35–37 °C for 18–24 h aerobically is common for many enteric organisms; adjust per compendial method or organism requirements.
• Atmosphere: Ambient air; CO2 atmosphere is generally unnecessary unless dictated by organism.
• Expected outcomes (illustrative, literature):
  • Lactose fermenters: pink/red colonies, potential bile precipitate zones.
  • Non‑fermenters: colorless to pale colonies.
• Controls: Include positive controls (e.g., known lactose‑positive and lactose‑negative strains) and a Gram‑positive organism to confirm selectivity.

These values are general literature practices and should be validated within your lab and regulatory framework. Item-specific performance criteria are Not specified for this item; refer to CoA/Spec Sheet and pharmacopeial chapters.

Safety and Handling

Classification for this specific catalog item is not provided. Always consult the product SDS for authoritative information.

• GHS classification, signal word, pictograms, H-statements: Not specified for this item; refer to SDS.
• General hazards (literature/good practice):
  • Dehydrated media can generate nuisance dust; avoid inhalation. Dyes (neutral red, crystal violet) can cause skin/eye irritation and persistent staining.
  • Crystal violet is a triarylmethane dye with potential mutagenic concerns in certain tests; minimize exposure and avoid aerosolization.
• PPE: Lab coat, safety glasses, disposable gloves. Use a dust mask/respirator if handling large quantities that may aerosolize (per institutional risk assessment).
• Engineering controls: Prepare solutions in a fume hood or well‑ventilated area; employ local extraction when weighing.
• Incompatibilities: Avoid strong oxidizers and strong acids/bases during storage. Do not mix dry medium with incompatible chemicals; prepare only with water specified for microbiological media.
• First aid (overview; follow SDS/institutional SOPs):
  • Inhalation: Move to fresh air; seek medical attention if symptoms persist.
  • Skin/eye contact: Rinse with water for at least 15 minutes; remove contaminated clothing; obtain medical advice if irritation continues.
  • Ingestion: Rinse mouth; seek medical attention.
• Autoclaving cautions: Do not tightly cap containers during sterilization; beware of superheating and pressure-related hazards. Allow media to cool to ~50 °C before pouring plates to reduce condensate and thermal burns.

Solvent Selection

This product is a culture medium, not a solvent. Solvent selection does not apply in the conventional sense. For practical use, only purified water is used for reconstitution.

Useful preparation notes (literature/general):

• Water quality: Use distilled or deionized water meeting microbiological media standards (e.g., low conductivity, low TOC, minimal residual disinfectants such as chlorine/chloramine which may inhibit growth).
• Dissolution: Sprinkle the dehydrated medium onto room‑temperature water with vigorous stirring to prevent clumping. Heat with agitation until the solution becomes clear to ensure complete agar dissolution.
• Sterilization: Autoclave per institutional SOPs (typical guidance in Application Protocols, literature). Avoid overheating that can degrade lactose and indicators, potentially increasing background or altering selectivity.
• Supplements: MacConkey formulations are typically complete as is. If selective supplements are added (e.g., antibiotics for specialty variants), verify compatibility and sterile-filter heat‑labile components before adding to cooled (≈50 °C) sterile base medium.

Storage and Reconstitution

• Storage conditions (as supplied): Room temperature (per Product Data). Protect from moisture and light; keep container tightly closed. Avoid high humidity that can cause clumping and performance drift.
• Shipping: Normal (per Product Data).
• Reconstitution: Item-specific reconstitution mass‑per‑liter is Not specified for this item; refer to CoA/Spec Sheet. See Application Protocols for general literature guidance on dissolution, sterilization, and pouring.
• Stability (general): Dehydrated media are typically stable for extended periods when dry and sealed. Once prepared, plates are best used fresh. If stored, keep at 2–8 °C, protected from desiccation/condensation, and observe internal shelf‑life/QC criteria.
• Freeze–thaw: Not applicable to dehydrated powder. Avoid freezing prepared plates unless validated, as freeze–thaw damages agar gel structure and alters selectivity/indicator performance.
• Research Use Note: For research use only.

For any item-specific specifications (recommended preparation concentration, final pH, gel strength, performance criteria), Not specified for this item; refer to CoA/Spec Sheet and SDS for safety.

Structure and Identity

MacConkey Agar (EP) is a dehydrated, complex culture medium blend, not a single defined chemical substance.

• Product type: Microbiological culture medium (selective and differential for Gram‑negative enteric bacteria)
• Composition (literature, typical): enzymatic digests of casein/animal tissues (peptones), lactose, bile salts, sodium chloride, agar, neutral red (pH indicator), crystal violet. Exact percentages and suppliers’ variants differ.
• Molecular formula: Not applicable (complex mixture)
• Molecular weight: Not applicable (complex mixture)
• SMILES / InChIKey: Not applicable to mixtures
• CAS / CID: Not assigned for the medium as a whole
• Structural features (descriptive):
  • Contains polysaccharide agar (gelling matrix) and amphiphilic bile salts that inhibit Gram‑positive organisms.
  • Neutral red enables pH‑dependent colony color (lactose fermentation → acidification → red/pink colonies with possible bile precipitate rims; non‑fermenters remain colorless or pale).
  • Crystal violet enhances selectivity against Gram‑positives by targeting cell wall synthesis.

Notes:

• This listing corresponds to an EP-compliant formulation context (European Pharmacopoeia) as indicated by “(EP)”. Item‑specific identity parameters (any unique composition specs) are Not specified for this item; refer to CoA/Spec Sheet.

Synthetic Utility

Not applicable to organic synthesis. MacConkey Agar (EP) is a microbiological culture medium rather than a chemical reagent for transformations.

For chemists needing selective media in biocatalysis or microbial screening workflows (literature/general):

• The medium can support microbial library screening for lactose utilization and bile tolerance traits, enabling genotype–phenotype linkage in metabolic engineering projects targeting enteric organisms.
• For plasmid maintenance or recombinant strain selection, MacConkey Agar is typically used without antibiotics; if antibiotics are required, confirm compatibility and add sterile‑filtered solutions after cooling to ≈50 °C.

If your workflow is primarily chemical (e.g., catalysis, synthesis), refer to reagents and solvents appropriate to your transformations; this product does not provide synthetic functional groups, redox activity, or acid/base catalysis in a controlled manner.

Target Specificity

This product is not an antibody or affinity reagent. There are no antigen/epitope targets.

Selectivity profile (literature/general for MacConkey medium):

• Favored recovery: Gram‑negative, bile‑tolerant enteric rods (e.g., many Enterobacteriaceae and related organisms).
• Inhibited/suppressed: Many Gram‑positive bacteria due to bile salts and crystal violet. Some fastidious Gram‑negatives may be partially inhibited; recovery can vary with strain condition.
• Differential response: Lactose fermenters vs non‑fermenters via neutral red color change and bile precipitation.

For regulated testing, define your target panel and acceptance criteria according to EP/USP/ISO methods and verify with growth promotion/suitability tests using specified reference strains. Item-specific organism recovery claims are Not specified for this item; refer to CoA/Spec Sheet.