MacConkey Agar (USP) - BioReagent

Cat. No.: M1528397

GRAU & PUREZA BioReagent

Storage

Room temperature

Shipped In

Normal

Visão geral

For selective isolation of intestinal bacteria

Especificações

Especificações e pureza

BioReagent

Condições de armazenamento de armazenamento

Room temperature

Enviado em

Normal

Grau

BioReagent

Product Line

Produtos biológicos

Application Protocols

• Item-specific tested applications and dilutions: Not specified for this item; refer to CoA/Spec Sheet.
• Literature/General protocol for plate preparation and use
  1. Medium preparation
     • Weigh the required mass of dehydrated MacConkey Agar (typ. ~50 g/L; exact per label) into a suitable vessel.
     • Add to ~1 L purified water with stirring; heat to dissolve. Do not overboil.
     • Autoclave at 121 °C for 15 minutes. Cool to 45–50 °C.
     • Optional: If bottle-sterilized, maintain at 45–50 °C in a water bath before pouring.
  2. Plate pouring
     • Pour 20–25 mL into sterile 90–100 mm petri dishes. Allow to solidify. Dry plates (e.g., 30–60 min at room temp with lids ajar in a biosafety cabinet) until surfaces are free of visible moisture.
  3. Inoculation and incubation
     • Streak for isolation or spread a measured sample volume for enumeration.
     • Incubate aerobically at 35–37 °C for 18–24 h (adjust per method).
  4. Interpretation (indicative)
     • Pink/red colonies (often with bile halo): lactose fermenters (e.g., E. coli, Klebsiella).
     • Colorless/pale colonies: non-lactose fermenters (e.g., Salmonella/Shigella).
     • Inhibited/no growth: many Gram-positives.
  5. QC (growth promotion testing)
     • Test positive control (e.g., E. coli ATCC strain) for characteristic growth/color and negative/inhibited control (e.g., S. aureus ATCC) for inhibition (literature). Record results.
• Biosafety note
  • Perform all manipulations in accordance with institutional biosafety procedures. Decontaminate work surfaces and autoclave waste.

Biological Roles

• Applicability note
  • As a culture medium, MacConkey Agar does not possess a singular biological role like a metabolite; instead, it modulates microbial growth and phenotype expression in vitro.
• Literature/General mechanistic basis
  • Selective agents: Bile salts and crystal violet disrupt cytoplasmic membranes and cell wall synthesis in Gram-positive organisms, allowing preferential growth of Gram-negative enterics.
  • Differentiation: Lactose is a fermentable carbohydrate; organisms with β-galactosidase and lactose permease generate acidic end-products that reduce local pH, shifting neutral red to its red/pink protonated form. Precipitation of bile salts around colonies can create a bile halo.
  • Sodium chloride maintains osmotic balance; peptones supply nitrogen, vitamins, and growth factors.
  • Agar provides a solid support with minimal nutritional contribution; its gel properties allow colony isolation and morphologic evaluation.
• Use in microbial ecology and physiology (general)
  • Enables assessment of coliform contamination, differentiation of enteric community structure (lactose vs non-lactose fermenters), and preliminary screening for pathogens (without constituting a diagnostic determination).
  • Employed in pharmaceutical and food microbiology for quality control and method verification (e.g., growth promotion testing per pharmacopeias).
• Limitations (general)
  • Some Gram-negative, fastidious organisms may be inhibited; some Gram-positives (e.g., enterococci) may grow weakly. Late lactose fermentation (e.g., Shigella typically non-lactose fermenting) requires confirmatory tests.
  • Indicator/dye concentrations and incubation conditions influence phenotype; interpret with appropriate controls.

Buffer Applications

• Not typically applicable
  • MacConkey Agar is not used as a buffering agent or for preparing analytical buffers. Its pH is set by formulation for microbiological selectivity and indicator performance.
• Literature/General note
  • The prepared medium has a near-neutral pH (around 7.1, literature) optimized for enteric bacteria and indicator response rather than buffering capacity. For experimental buffers, choose defined systems (e.g., phosphate, Tris, HEPES) appropriate to your application.

Green Alternatives

• Context
  • Traditional “green solvent” comparisons are not directly relevant to culture media. Nevertheless, sustainability considerations apply to media preparation and use.
• Literature/General recommendations
  • Ready-to-use vs dehydrated: Dehydrated media minimize cold-chain transport and packaging weight, often lowering carbon footprint relative to pre-poured plates. On-site preparation requires autoclave energy—batch efficiently to optimize load factors.
  • Water and energy conservation: Use insulated autoclave cycles, avoid unnecessary sterilization repeats, and prepare only required volumes to reduce waste.
  • Waste minimization: Use reusable glassware where permitted, and segregate biohazard waste to limit incineration volume. Neutralize disinfectants before disposal when required by local regulations.
  • Material choices: Opt for PETG or other recyclable plastics for plate sleeves and consider plate recycling programs where validated.
• Alternatives in selectivity (methodological, not greener per se)
  • Chromogenic media can reduce confirmatory subcultures and reagent use by providing direct differentiation (literature). Trade-off: higher per-plate resource intensity.
  • Membrane filtration with selective media can reduce overall medium consumption for water testing.
• Item-specific environmental attributes
  • No specific eco-profile provided for this item. Any life-cycle or packaging details are Not specified for this item; refer to CoA/Spec Sheet.

Pharmaceutical Uses

• Applicability note
  • No therapeutic or clinical claims. The following refers to laboratory and manufacturing quality control contexts only.
• Literature/General roles in pharmaceutical microbiology
  • Referenced in pharmacopeial microbiological examination methods (e.g., USP) for the selective isolation and differentiation of coliforms and other enteric Gram-negative bacteria from non-sterile products and environments.
  • Used in Growth Promotion Testing (GPT) to verify medium performance and to qualify test methods for microbial limits and environmental monitoring.
  • Employed during bioburden assessments, raw material testing, and water system monitoring when detection of lactose-fermenting enterics is required.
• Compliance considerations
  • When pharmacopeial compliance is required, verify each lot’s certificate for formulation, pH of prepared medium, and performance with prescribed challenge organisms. For this item, specific compliance statements are Not specified for this item; refer to CoA/Spec Sheet.
• Practical notes (general)
  • Follow data integrity and traceability practices: record lot numbers, preparation date, sterilization parameters, and GPT results.
  • Use positive and negative controls per USP (e.g., E. coli ATCC strain as positive; S. aureus ATCC as inhibited control) to document selectivity and differential response.

Physical Properties

• Item-specific (Product Data)
  • Appearance: Not specified for this item; refer to CoA/Spec Sheet.
  • Storage Conditions: Room temperature
  • Shipping: Normal
  • Other physicochemical specs (e.g., moisture %, pH, particle size): Not specified for this item; refer to CoA/Spec Sheet.
• Literature/General properties for dehydrated MacConkey Agar
  • Physical form: Free-flowing, homogeneous, pink-beige to red-tinted powder (due to neutral red/crystal violet dyes) that gels on hydration and sterilization.
  • Solubility: Dispersible in water; upon heating to near boiling the agar dissolves, forming a clear to slightly opalescent solution that gels on cooling (approx. 1.2–1.5% agar forms firm gel) (literature).
  • pH of prepared medium: Typically around 7.1 ± 0.2 at 25 °C before sterilization (literature). Final color of plates is pale to rose-red; lactose fermentation yields pink/red colonies with precipitated bile halo.
  • Thermal behavior: Agar melts at ~85–90 °C and solidifies at ~32–40 °C, exhibiting hysteresis (literature). Autoclaving commonly performed at 121 °C for 15 minutes.
  • Density/RI/BP/MP/logP: Not applicable to this multicomponent solid; individual-component values are not meaningful for the whole formulation.
• Practical notes
  • Dissolution is improved by gradual addition to warm water with vigorous stirring; avoid charring.
  • Precipitation/cloudiness can arise from hard water or overheating; use distilled/deionized water and avoid prolonged boiling (literature guidance).

Quality and Grades

• Item-specific (Product Data)
  • Grade: BioReagent
  • Additional grade-specific specs (e.g., performance criteria, microbial testing panel, pH tolerance): Not specified for this item; refer to CoA/Spec Sheet.
• What BioReagent typically implies (general)
  • Intended for laboratory and research applications, with quality controls suitable for consistent experimental performance. It is not a clinical diagnostic product and is labeled For research use only.
• About “USP” designation in the product name (literature/general)
  • MacConkey Agar is described in pharmacopeial methods (e.g., USP/EP) for selective isolation and differentiation of lactose-fermenting Gram-negative enteric bacteria. The USP formulation specifies qualitative/quantitative components and performance tests with defined strains.
  • For this specific item, formal certification or lot-specific compliance to a USP monograph is Not specified for this item; refer to CoA/Spec Sheet. When pharmacopeial compliance is required (e.g., pharmaceutical QC), verify conformance through the provided certificate and perform incoming QC with reference strains.
• Stabilizers and additives
  • This medium normally relies on intrinsic stability of dehydrated components; external stabilizers are generally not used. Any stabilizers, if present, are Not specified for this item; refer to CoA/Spec Sheet.
• Practical QC suggestions (general)
  • Conduct growth promotion testing (GPT) per USP with appropriate positive/negative controls.
  • Verify appearance (color, homogeneity), pH of prepared medium, and absence of contamination before use.

Reaction and Applications

• Applicability note
  • This section is adapted to the functional applications of MacConkey Agar in microbiology rather than chemical synthesis.
• Literature/General applications
  • Selective isolation of Gram-negative enteric bacilli from clinical, environmental, food, and pharmaceutical samples due to inhibition of Gram-positive flora by bile salts and crystal violet.
  • Differential identification based on lactose fermentation:
    • Lactose fermenters (e.g., Escherichia coli, Klebsiella spp.) produce acid, turning colonies pink/red with potential bile precipitation halos as neutral red indicator responds.
    • Non-lactose fermenters (e.g., Salmonella, Shigella, Proteus) remain colorless to pale, often transparent.
  • Typical use contexts: Environmental monitoring, hygiene testing, water analysis for coliforms, and growth promotion testing in pharmacopeial methods (literature).
• Practical tips (general)
  • Dry plates before inoculation to avoid swarming (e.g., Proteus) and to achieve discrete colonies.
  • Incubate aerobically at 30–37 °C depending on compendial method; evaluate plates at 18–24 h and, if required, at 48 h (literature).
  • For stressed or injured cells, consider resuscitation on nonselective media prior to MacConkey to avoid false negatives.
  • Avoid excessive autoclaving or overheating that can degrade sugars/indicators, leading to background color or reduced selectivity.
• Item-specific application statements
  • Manufacturer Applications: Not specified for this item; refer to CoA/Spec Sheet.
  • Research Use Note: For research use only.

Reaction Conditions

• Adapted to medium preparation conditions (literature/general). Not item-specific; verify against label/CoA for this lot.
• Typical preparation parameters
  • Concentration: Commonly ~50 g of dehydrated medium per 1 L of purified water; exact value Not specified for this item; refer to CoA/Spec Sheet.
  • Dissolution: Add powder gradually with vigorous stirring. Heat to boiling until agar fully dissolves; avoid prolonged overheating to preserve lactose/indicator integrity.
  • Sterilization: Autoclave at 121 °C for 15 minutes. After autoclaving, cool to 45–50 °C before pouring plates (to minimize condensation and preserve dye function).
  • Plate pouring: 20–25 mL per standard 90–100 mm petri dish yields ~4 mm depth (literature). Allow plates to set; dry surface prior to inoculation.
• Incubation and performance (general)
  • Inoculation: Streak for isolation or spread measured volumes for quantitative assays.
  • Incubation: Aerobic, typically 35–37 °C for 18–24 h (adjust per method); some applications use 30 °C.
  • Expected outcomes: Lactose fermenters form pink/red colonies; non-fermenters remain colorless/pale. Gram-positive organisms generally inhibited.
• Quality checks
  • pH (room temperature): Approximately 7.1 before sterilization (literature). Verify with a calibrated pH meter after preparation; adjust only if allowed by your method.
  • Growth Promotion Testing: Perform with compendial strains to document selectivity and differential response before routine use.

Safety and Handling

• Item-specific (Product Data)
  • GHS classification, signal word, pictograms, H-statements: Not specified for this item; refer to SDS.
  • Storage: Room temperature; ship normal.
• General safety (literature/guidance; defer to SDS and institutional biosafety policies)
  • Chemical hazards: Dehydrated medium typically presents low acute chemical hazard, but dyes (crystal violet, neutral red) can be irritants or stains. Avoid inhalation of dust and contact with eyes/skin.
  • Biological hazards: When prepared and inoculated, this medium supports growth of enteric Gram-negative bacteria, including potential pathogens. Handle cultures at an appropriate biosafety level (often BSL-2). Implement engineering controls (biosafety cabinet for manipulations generating aerosols).
  • PPE: Laboratory coat, nitrile gloves, and safety glasses as minimum. Use respiratory protection if dust generation cannot be controlled during weighing/dispensing.
  • Incompatibilities: Avoid mixing concentrated dehydrated medium with strong oxidizers or acids/bases that could degrade dyes/agar. Protect from moisture to prevent clumping and microbial contamination of powder.
  • Hygiene: Do not eat, drink, or apply cosmetics in laboratory areas. Wash hands thoroughly after handling.
  • First aid (overview; consult SDS):
    • Inhalation of dust: Move to fresh air; seek medical attention if symptoms persist.
    • Skin/eye contact: Rinse with water for several minutes; remove contaminated clothing; obtain medical advice if irritation continues.
    • Ingestion: Rinse mouth; seek medical advice.
  • Waste and decontamination: Autoclave used plates/broths and contaminated disposables at 121 °C for ≥15 minutes before disposal. Use appropriate chemical disinfectants (e.g., 10% bleach) for surface decontamination (literature).

Solvent Selection

• Applicability note
  • Solvent selection, in the chromatographic or reaction-solvent sense, is not directly applicable to a dehydrated culture medium. The relevant “solvent” is purified water for reconstitution.
• Literature/General guidance for reconstitution
  • Use freshly prepared distilled or deionized water; avoid hard/ion-rich water that can cause precipitation or haze.
  • Typical working concentration: Many MacConkey Agar formulations are prepared at ~50 g/L (literature). Consult the product label/CoA for the exact mass per liter for this item (Not specified for this item; refer to CoA/Spec Sheet).
  • Heating: Suspend powder in cold/warm water with stirring; heat to near boiling to dissolve agar fully. Do not overboil.
  • Sterilization: Autoclave at 121 °C for ~15 minutes (literature). Cool to ~45–50 °C before pouring plates to minimize condensation and to protect heat-sensitive indicators.
• Comparison to alternatives (general)
  • Water quality tiers: ASTM Type I vs Type II water; Type I minimizes background precipitation and ensures reproducibility.
  • Alternative media: If minimal salt or different selectivity is required, consider Eosin Methylene Blue (EMB) Agar or CHROMogenic media (literature). Selection should be based on target organisms and required differentiation.
• Container/material compatibility
  • Use borosilicate glass bottles or validated heat-resistant plastics for autoclaving. Avoid aluminum foil directly contacting hot, dye-containing media to prevent staining/interaction.

Storage and Reconstitution

• Item-specific (Product Data)
  • Storage Conditions: Room temperature
  • Shipping: Normal
  • Reconstitution specifics for this item (mass per liter, target pH, performance criteria): Not specified for this item; refer to CoA/Spec Sheet.
• Literature/General guidance
  • Storage of dehydrated powder: Keep tightly closed in a cool, dry place, protected from moisture, light, and volatile chemicals. Reseal promptly after each use to prevent clumping and contamination.
  • Shelf life: Use within the labeled expiry date; once opened, monitor for caking, color change, or odor as signs of degradation (general guidance).
  • Reconstitution (typical): Suspend the labeled amount (often ~50 g/L) in purified water, heat to dissolve, autoclave at 121 °C for 15 min, cool to 45–50 °C, and pour plates. Do not overheat to avoid sugar/indicator degradation.
  • Prepared plates: Store inverted at 2–8 °C in sealed sleeves to minimize desiccation and contamination. Allow to warm to room temperature and dry surface condensate before use. Use within 2–4 weeks for best performance (literature), or per validated in-house expiry.
  • Freeze–thaw: Not applicable to dehydrated medium; avoid freezing prepared plates as it compromises gel integrity and performance.
  • Traceability: Record lot number, preparation date, sterilization parameters, and any pH adjustments in laboratory logs.

Structure and Identity

• Item-specific (Product Data)
  • Product: MacConkey Agar (USP), SKU M1528397
  • Type: Complex, dehydrated culture medium (mixture), not a single defined chemical entity
  • Grade: BioReagent
  • CAS, InChIKey, SMILES, Molecular Formula, Molecular Weight: Not specified for this item; refer to CoA/Spec Sheet.
• Literature/General information (for MacConkey Agar as a medium)
  • Nature: A composite mixture typically containing peptones, bile salts, lactose, sodium chloride, neutral red (pH indicator), crystal violet (selective agent), and agar as gelling agent.
  • Identity concept: Because this is a multicomponent, undefined medium, conventional small-molecule identifiers (SMILES, InChI) do not apply. Identity is established by formulation, performance (growth/selectivity), and compliance with reference monographs (e.g., USP/EP) where applicable.
  • Structural features (descriptive):
    • Agar: linear galactan polysaccharide (agarose/agaropectin) providing a gel matrix.
    • Bile salts/crystal violet: cationic dye and bile components that disrupt cell walls/membranes of Gram-positive bacteria, conferring selectivity.
    • Neutral red: cationic pH indicator that becomes red in acidic microenvironments produced by lactose fermentation.
    • Peptones: hydrolysates of proteins providing amino acids/peptides; chemically complex and variable.
• General notes for professionals
  • Identity verification is typically by QC performance tests using specified organisms (e.g., E. coli positive, Salmonella/Shigella lactose-negative, Staphylococcus inhibited) and pH/color response rather than by a single structural metric.
  • “USP” in the name refers to the standard MacConkey Agar formulation used in pharmacopeial microbiological methods (literature); item-specific certification status is Not specified for this item; refer to CoA/Spec Sheet.

Synthetic Utility

• Not applicable to chemical synthesis
  • MacConkey Agar is a complex culture medium and is not employed as a reagent or building block in chemical synthesis. For this product, see Biological Roles, Reaction & Applications, and Application Protocols for relevant use cases.

Target Specificity

• Not an antibody/biomolecule
  • This product has no antigen/epitope specificity, clone, or isotype.
• Literature/General selectivity profile of MacConkey Agar
  • Intended to recover Gram-negative enteric bacilli while inhibiting many Gram-positive organisms via bile salts and crystal violet.
  • Differential for lactose fermentation:
    • Target phenotype: Lactose fermenters (e.g., Escherichia coli) produce pink to red colonies due to acidification (neutral red indicator) and may show bile precipitation.
    • Non-target/contrast phenotype: Non-lactose fermenters (e.g., Salmonella, Shigella, Proteus) yield colorless to pale colonies.
  • Some exceptions: Certain Gram-positive enterococci may grow weakly; mucoid colonies in Klebsiella/Enterobacter due to capsule formation (literature).
• Item-specific performance panel
  • Lot-specific target organism lists and acceptance criteria are Not specified for this item; refer to CoA/Spec Sheet.