Voges-Proskauer Semi-Solid Agar (VP) - BioReagent

Cat. No.: V1528345

GRADE & PURITY BioReagent

Storage

Room temperature

Shipped In

Normal

Overview

For bacterial V-P test

Specifications

Specifications & Purity

BioReagent

Storage

Room temperature

Shipped In

Normal

Grade

BioReagent

Product Line

Biological Products

Application Protocols

Item-specific, validated protocols are Not specified for this item; refer to CoA/Spec Sheet and product label. Below is a general research protocol for VP testing on semi-solid agar (literature, not item-specific):

• Preparation
  • Reconstitute and sterilize the medium per label. Dispense to sterile tubes to form a semi-solid column; allow to set.
• Inoculation
  • Using a sterile needle, stab-inoculate centrally to ~2/3 depth, or streak the surface if surface growth is preferred. Include a VP-positive and VP-negative control strain.
• Incubation
  • Incubate at 35–37 °C for 24–48 h (organism-dependent). Ensure tubes remain upright for consistent oxygen exposure at the surface.
• VP reaction
  • To each tube, add VP Reagent A (α‑naphthol in ethanol) followed by VP Reagent B (40% KOH; creatine optional as catalyst). Use freshly prepared reagents. Do not invert vigorously; gently mix at the surface.
  • Observe for development of a cherry-red color in the upper aerobic zone within 10–60 min. A copper/brown coloration without red is not positive.
• Interpretation and QC
  • Compare test results to controls. Record time to positivity. If negative at 60 min, reincubate and recheck or verify organism identity.

Dispose of cultures and reagents by validated decontamination. For research use only.

Biological Roles

• Nature of product: A nutrient matrix intended to support microbial growth and to enable detection of acetoin production via the VP reaction. It does not itself have a single biological role as a defined molecule; rather, it provides a controlled environment for metabolism observation.

• Biological principles leveraged (literature, general):

  • Carbohydrate fermentation pathways diverge to mixed-acid (MR-positive) vs. butylene glycol (VP-positive) end products. The VP assay detects intermediates (acetoin/diacetyl) formed by VP-positive organisms under aerobic conditions.
  • Semi-solid agar modulates oxygen availability and mass transfer, affecting red complex formation near the surface where oxidation is favored.

• Research applications:

  • Taxonomic and functional differentiation within Enterobacteriaceae and other bacteria as part of IMViC or extended biochemical panels.
  • Screening engineered strains for redirected carbon flux (e.g., toward 2,3-butanediol production) by monitoring acetoin generation (literature, general).

• Limitations:

  • Some organisms produce weak/slow VP reactions; timing and reagent freshness are critical to avoid false negatives/positives.
  • High cell density or overly reduced conditions may suppress color development; ensure adequate aeration of the reaction zone.

Item-specific organism performance claims are Not specified for this item; refer to CoA/Spec Sheet.

Buffer Applications

This product is a culture medium, not a buffering reagent. It is not typically used to prepare standalone buffer systems.

• Context (literature, general): Many microbiological media include intrinsic buffering capacity (often from phosphates/peptones) to maintain pH during growth, but exact buffer components and pH ranges are formulation-dependent and not specified here.
• If a defined buffer is required for your workflow (e.g., post‑growth washes), prepare a separate, validated buffer (PBS, phosphate buffer, etc.) and use the culture medium solely for growth and VP testing.

Item-specific buffer composition and pH specifications: Not specified for this item; refer to CoA/Spec Sheet.

Green Alternatives

• Environmental context: Culture media preparation consumes water, energy (autoclaving), and single-use plastics. Semi-solid VP agar can be optimized to reduce resource use in research while maintaining data quality.

Options and trade-offs (literature, general)

• Ready-to-use formats vs. dehydrated media
  • Ready-to-use tubes/plates reduce on-site sterilization energy but increase packaging waste and refrigerated transport. Dehydrated media minimize shipping mass/volume and are stable at room temperature (this item: stored at room temperature), but require autoclaving energy.
• Miniaturization
  • Performing VP tests in microtubes or microplates with small semi-solid volumes reduces media consumption and biohazard waste. Requires tighter control of evaporation and oxygen exposure.
• Reuse and segregation
  • Use reusable glassware and segregate uncontaminated packaging for recycling. Validate cleaning to avoid cross-contamination.
• Energy efficiency
  • Batch autoclave runs at full load; avoid over-processing. Consider gravity vs. vacuum cycles matched to load type to reduce time/energy.
• Chemical footprint
  • Avoid unnecessary additives; prepare only the volume needed to limit expired waste. Select low-toxicity cleaning agents compatible with microbiology work.

Note: These are general sustainability practices. Item-specific environmental attributes and lifecycle data are Not specified for this item; refer to CoA/Spec Sheet if available.

Pharmaceutical Uses

Direct pharmaceutical or excipient applications are not applicable to this microbiological research medium.

• Relevant industrial/research contexts (literature, general):
  • Used in industrial microbiology and QC laboratories for research-grade microbial characterization and training, including fermentation pathway assessments as part of strain development.
  • Can support method development or suitability testing in laboratories that also perform pharmacopeial microbiology, but this specific item is designated For research use only and is not represented as a compendial medium.

Regulatory/compendial status and suitability for GMP/GLP use: Not specified for this item; consult your quality unit and refer to CoA/Spec Sheet if regulatory alignment is required.

Physical Properties

Item-specific specifications (appearance, pH of prepared medium, moisture, ash, clarity)

• Not specified for this item; refer to CoA/Spec Sheet.

General/literature characteristics for dehydrated semi‑solid VP media (for context; not item-specific)

• Physical form: Free-flowing, hygroscopic powder that forms a semi‑solid gel after dissolution and sterilization (literature, general).
• Final gel strength: Lower than standard agar plates due to reduced agar content to create a semi‑solid consistency that supports limited motility and appropriate oxygen diffusion (literature, general).
• Solubility: Designed to be soluble in purified water with heat; complete dissolution typically achieved before sterilization (literature, general).
• Typical final pH (at 25 °C): Often near 6.9 ± 0.2 after preparation, depending on formulation (literature, general; not a specification for this item).
• Optical properties: Prepared medium is usually slightly opalescent; clarity depends on peptone content and gelling level (literature, general).

Notes

• Use freshly produced, deionized/distilled water for preparation to minimize variability.
• Avoid overheating during dissolution to preserve nutrient integrity (literature, general). Always verify actual specifications on the product label/CoA.

Quality & Grades

• Item grade: BioReagent (per Product Data).
• Meaning in context: BioReagent-grade products are intended for biological research workflows, with manufacturing controls suitable for reproducible microbiological or biochemical applications. While not equivalent to clinical/diagnostic grades, BioReagent materials emphasize consistency, low bioburden in the dehydrated state, and performance in stated research applications.
• What this implies for this product:
  • Formulated to perform in the Voges–Proskauer test in semi-solid format when prepared per label.
  • Typical QC for media may include growth promotion/inhibition and pH/gelation checks (general), but item-specific acceptance criteria are Not specified for this item; refer to CoA/Spec Sheet.
• Stabilizers or additives: Not specified for this item; refer to CoA/Spec Sheet.
• UV absorbance, metal content, peroxide levels, endotoxin: Not applicable/Not specified for this item; refer to CoA/Spec Sheet if relevant.
• Documentation: For lot-specific performance and composition, consult the Certificate of Analysis (CoA) and product Specification Sheet. These documents supersede general statements here.

Reaction & Applications

Primary application (per product name and category): Voges–Proskauer (VP) Semi-Solid Agar for detection of acetoin (acetylmethylcarbinol) production by microorganisms as part of fermentation profiling.

• Principle (literature, general): Organisms fermenting glucose via the butylene glycol pathway produce acetoin, which is detected after adding VP reagents (α‑naphthol and KOH/creatine). Oxidation of acetoin to diacetyl followed by reaction with guanidine-containing compounds yields a cherry-red complex at the surface/aerobic zone.
• Why semi‑solid: The semi-solid matrix promotes a shallow oxygen gradient and restricts convection, helping localize color development in the upper portion while supporting growth. It can also allow observation of limited motility patterns (literature, general).
• Typical research uses:
  • Differentiation within Enterobacteriaceae and related Gram-negatives (e.g., Enterobacter/Klebsiella often VP-positive; Escherichia/Shigella typically VP-negative) and certain Gram-positives (literature, general).
  • Strain characterization in industrial/academic microbiology, metabolic engineering screening, and teaching labs (research use only).
• Procedural notes (literature, general):
  • Inoculate and incubate at 35–37 °C for 24–48 h (as organism-appropriate). After incubation, add VP reagents to the surface and observe for red color formation in up to 60 min.
  • Use positive and negative controls each run to verify reagent performance.

Item-specific performance claims and organism lists are Not specified for this item; refer to CoA/Spec Sheet.

Reaction Conditions

As a culture medium, relevant “conditions” refer to media preparation, sterilization, incubation, and the VP colorimetric reaction rather than chemical synthesis.

General guidance (literature, not item-specific)

• Reconstitution: Suspend the labeled mass of dehydrated medium in purified water with heat and stirring until fully dissolved. Exact g/L is Not specified for this item; follow the product label.
• Sterilization: Autoclave at 121 °C for 15 minutes (standard gravity cycle), unless the label instructs otherwise. Avoid prolonged heating to prevent sugar degradation.
• Pouring/solidification: Cool to ~50–55 °C and dispense into sterile tubes to achieve a semi-solid depth (e.g., a few mL per tube). Allow to solidify upright to create a flat surface.
• Inoculation/incubation: Stab-inoculate or surface-inoculate as required. Incubate typically at 35–37 °C for 24–48 h, organism-dependent.
• VP development: Add freshly prepared VP reagents sequentially to the surface (α‑naphthol, then KOH/creatine; volumes scaled to tube size). Mix gently at the surface. Observe for red coloration in the upper aerobic zone within 10–60 minutes. Include positive/negative controls.

Always consult the product label/CoA for item-specific instructions and verify performance with controls. This product is For research use only.

Safety & Handling

Item-specific GHS/SDS fields

• Signal word: Not specified for this item; refer to SDS.
• H-statements / GHS classification / pictograms: Not specified for this item; refer to SDS.

General laboratory safety guidance for dehydrated microbiological media (literature, general)

• Hazards: Powders may cause dust irritation to eyes, skin, and respiratory tract. Handle to minimize dust formation. Not for human or animal use—For research use only (per Product Data).
• PPE: Wear lab coat, nitrile gloves, safety glasses/goggles. Use a dust mask/respirator if airborne dust cannot be controlled.
• Handling: Avoid moisture ingress; close container promptly. Prepare in a clean area to prevent microbial contamination. When working with live cultures, use biosafety practices appropriate to the organism (e.g., BSL-1/2 as applicable) and biological safety cabinets for aerosols.
• Incompatibilities: Keep away from strong oxidizers and moisture. Do not store near volatile chemicals that can be absorbed by the medium.
• Sterilization: Autoclave media and disposables according to institutional policy (commonly 121 °C, 15 min; literature, general). Allow pressure to dissipate before opening autoclave to avoid boil-over.
• First aid (overview): If inhaled, move to fresh air; if on skin/eyes, rinse with water for several minutes; if ingested, rinse mouth—seek medical advice if symptoms persist. Defer to SDS for authoritative instructions.
• Waste: Decontaminate biological waste by autoclaving or validated chemical disinfection prior to disposal per local regulations.

Solvent Selection

This product is a dehydrated culture medium; “solvent selection” concerns the water quality used for reconstitution rather than organic solvent choice.

• Recommended solvent: Purified water (distilled or deionized) suitable for microbiological media preparation.
• Water quality parameters (literature, general):
  • Conductivity/resistivity consistent with lab DI (e.g., ≥10–15 MΩ·cm) to limit ionic variability.
  • Low TOC and absence of residual disinfectants (chlorine/chloramine) that can inhibit growth.
  • Filtration: Use clean glassware; pre-filter water if particulates are present.
• Practical guidance:
  • Heat with stirring to fully dissolve the dehydrated medium before sterilization.
  • Avoid alkaline glass leaching: use borosilicate flasks in good condition; do not overboil.
  • Do not add organic solvents; they are not required and may inhibit microbial growth or interfere with the VP reaction.
• Comparison to alternatives (literature, general):
  • Tap water: convenient but variable hardness/chlorine—may compromise results.
  • RO-only water: acceptable if stable quality is verified; polishing with mixed-bed ion exchange and UV is preferred for sensitive media.

Always follow the product label for the exact water-to-powder ratio. Item-specific preparation quantities are Not specified for this item; refer to CoA/Spec Sheet.

Storage & Reconstitution

• Storage conditions (per Product Data): Room temperature. Keep container tightly closed in a dry place. Protect from humidity to prevent clumping and loss of performance. Shipped under normal conditions.
• Shelf life: Not specified for this item; refer to CoA/Spec Sheet.

Reconstitution and preparation (literature, general; follow label for exact quantities)

• Water: Use freshly produced distilled/deionized water. Amount per liter is specified on the product label (Not specified for this item).
• Dissolution: Add powder to water with stirring and gentle heat until fully dissolved. Avoid scorching.
• Sterilization: Autoclave at 121 °C for 15 minutes unless otherwise directed by the label.
• Dispensing: Cool to ~50–55 °C and dispense aseptically into sterile tubes to obtain a semi-solid depth suitable for the assay.
• Additives: Do not add VP reagents to the medium prior to sterilization. VP reagents (α‑naphthol, KOH/creatine) are applied post-incubation to the culture surface.

Post-preparation handling

• Store prepared tubes at 2–8 °C protected from light and desiccation; bring to room temperature before use (literature, general). Monitor for dehydration or contamination; discard if compromised.

Research use note: For research use only (per Product Data).

Structure & Identity

• Item type: Dehydrated, complex microbiological medium formulated for the Voges–Proskauer (VP) test in a semi-solid agar format.
• Composition nature: Mixture of organic and inorganic nutrients and gelling agent(s). Exact qualitative/quantitative composition is not provided here.
• Molecular formula: Not applicable to complex mixtures.
• Molecular weight: Not applicable to complex mixtures.
• SMILES / InChI / InChIKey: Not applicable (mixture).
• CAS / CID: Not applicable (formulated medium).
• Structural features (descriptive): Semi-solid media are typically based on a low-percentage agar matrix to enable limited diffusion and to maintain a shallow oxygen gradient; nutrient fractions commonly include peptones and carbohydrate sources alongside buffering salts (literature, general). This product is intended to support growth and enable the VP reaction to detect acetoin production after addition of VP reagents.

Item-specific identifiers and detailed composition: Not specified for this item; refer to CoA/Spec Sheet.

Synthetic Utility

Not a chemical synthesis reagent. This product does not serve as a precursor, catalyst, or solvent in organic synthesis.

• If your workflow involves chemical derivatization or analytics, prepare extracts from cultures grown on this medium and perform chemistry in appropriate analytical solvents outside the biological matrix (literature, general).
• For media optimization or custom formulations, consider designing defined media separately; do not treat this complex medium as a tunable synthetic feedstock without full compositional knowledge.

Item-specific reactivity or chemical roles: Not applicable.

Target Specificity

Not applicable. This product is a microbiological culture medium and does not possess antibody/ligand target specificity, epitope recognition, clone, or isotype attributes.