Hektoen Enteric Agar - BioReagent

Cat. No.: H1528634

GRADE & PURITY BioReagent

Storage

Room temperature

Shipped In

Normal

Übersicht

For selective isolation of intestinal pathogens

Specifications

Spezifikationen & Reinheit

BioReagent

Storage

Room temperature

Verschickt in

Normal

Note

BioReagent

Product Line

biological_products

Application Protocols

General, literature-based protocol for plate preparation and use (not item-specific):

Plate preparation

• Weigh the medium according to the CoA/Spec Sheet (exact g/L Not specified for this item). Suspend in purified water with stirring.
• Heat to dissolve fully; autoclave at 121 °C for 15 min. Cool to 45–50 °C, mix gently, and pour sterile plates. Allow to solidify and dry.
• Store plates inverted at 2–8 °C in sealed sleeves to prevent desiccation.

Inoculation and incubation

• Bring plates to room temperature. Streak clinical or environmental specimens using a quadrant streak for isolation.
• Incubate inverted plates at 35–37 °C for 18–24 h (up to 48 h if needed).

Interpretation (presumptive; confirm with further tests)

• Lactose/sucrose/salicin fermenters: yellow to salmon colonies; surrounding medium may yellow.
• Non‑fermenters (e.g., Shigella): green to blue‑green colonies, typically without blackening.
• H2S producers (e.g., many Salmonella): colonies with black centers or entirely black due to H2S reacting with ferric ions.

Controls and QC

• Include appropriate positive/negative control strains per your SOP to verify selectivity and differential performance each lot.

Biosafety

• Treat all inoculated plates as biohazardous; autoclave before disposal. Use BSL‑2 practices as appropriate.

Biological Roles

This product does not have a singular biological role as a molecule; it functions as a culture medium supporting and differentiating bacteria (literature context).

• Nutritional support: complex nitrogen and carbon sources (peptones, yeast extract) provide amino acids, vitamins, and growth factors for Gram‑negative enterics.
• Selectivity: bile salts inhibit many Gram‑positive organisms and some fastidious Gram‑negatives, enriching for enteric Gram‑negative rods.
• Differential biochemistry captured on‑plate:
  • Carbohydrate fermentation: metabolism of lactose, sucrose, and/or salicin leads to acid production; pH indicators shift from green to yellow‑orange around colonies.
  • Sulfur metabolism: reduction of thiosulfate to H2S by bacteria with appropriate pathways (e.g., Salmonella via thiosulfate reductase) yields black precipitates with ferric ions.
• Phenotypic readouts:
  • H2S‑positive non‑fermenters (e.g., many Salmonella) appear green with black centers.
  • Shigella typically forms green, translucent colonies without blackening (non‑fermenter, H2S‑negative).
  • Coliform fermenters (e.g., E. coli, Klebsiella) produce yellow to salmon colonies, sometimes with a surrounding yellow zone due to acid diffusion.

These readouts guide downstream confirmatory identification; they do not replace biochemical or molecular confirmation. For research use only (per Product Data).

Buffer Applications

Not typically applicable. Hektoen Enteric Agar is a selective/differential culture medium and is not used as a buffering reagent in solution chemistry or biochemistry. If a buffering system is required for your workflow, prepare the buffer separately and use HE Agar exclusively for microbiological plating and phenotypic differentiation.

Green Alternatives

Environmental considerations for culture media center on water/energy use, waste minimization, and safe dye handling rather than solvent toxicity.

• Process improvements (general best practice):

  • Prepare only the volume needed to reduce expired plate waste; store poured plates refrigerated and protected from desiccation to maximize useful life.
  • Optimize autoclave cycles (validated 121 °C/15 min liquid cycle) to minimize energy consumption while ensuring sterility.
  • Use reusable glassware where feasible; segregate biohazard waste and autoclave before disposal to prevent environmental release of microorganisms.

• Alternative media comparison (literature context; selection depends on target organisms):

  • HE Agar vs XLD Agar: XLD uses xylose/lysine/deoxycholate and can show sharper lysine decarboxylation effects; HE offers a distinct color scheme and robust H2S detection. Choice can be based on lab familiarity and local validation rather than inherent “greenness.”
  • HE Agar vs SS Agar: SS is highly selective and may suppress some Shigella; HE can provide better recovery of Shigella while still inhibiting competing flora.

• Chemical components:

  • Indicator dyes and bile salts should be handled to avoid release to drains; follow institutional chemical hygiene plans.

No specific “green certification” or reduced‑hazard formulation is specified for this item; consult the CoA/Spec Sheet for any manufacturer sustainability notes.

Pharmaceutical Uses

No clinical or therapeutic claims are made for this product. For research use only (per Product Data).

Industry context (literature, non‑item‑specific):

• Microbiological media such as Hektoen Enteric Agar may be employed in pharmaceutical and food industry quality control laboratories for environmental monitoring and testing of raw materials or finished products for enteric contaminants, where validated by internal procedures.
• Compendial status: HE Agar is widely described in microbiology texts; specific pharmacopeial monographs or method references can vary by region and application. Users should consult applicable pharmacopeias (e.g., USP, EP) and internal SOPs for acceptance criteria and suitability tests.
• Role in workflows: plating of enrichment cultures or direct samples to selectively recover and presumptively differentiate target Gram‑negative enterics prior to confirmatory identification.

Documentation and validation:

• Use lot‑specific CoA/Spec Sheet to document preparation parameters and performance characteristics.
• Validate the medium for intended use with appropriate positive/negative control strains as part of method suitability studies.

Physical Properties

Item-specific properties (from Product Data):

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Storage conditions: Room temperature (per Product Data).
• Shipping: Normal (per Product Data).

General/literature characteristics for dehydrated HE Agar (not item-specific; for context):

• Physical form: free‑flowing, heterogeneous dehydrated powder; color often tan to greenish due to indicators and bile salts.
• Solubility: intended to be dispersed and boiled in purified water; forms a gel upon cooling after sterilization due to agar.
• pH of prepared medium: typically ~7.5 ± 0.2 at 25 °C (literature value; final pH after sterilization).
• Gelation: solid at room temperature when ~1.3–1.6% agar; melts on heating and resolidifies on cooling (reversible physical gel).
• Odor: mild, characteristic of peptones (literature).

Not applicable/Not defined for mixtures (reporting as literature context only, not specifications for this item):

• Boiling/melting point: not meaningful for a multi‑component medium; agar shows softening rather than a sharp melting point.
• Density, refractive index, logP, pKa: not defined for a complex dehydrated medium.

Always confirm lot‑specific appearance, pH, and performance on the CoA/Spec Sheet for this item.

Quality and Grades

• Item-specific grade: BioReagent (per Product Data). In the Aladdin Scientific context, BioReagent indicates suitability for general laboratory biological workflows (e.g., microbial culture, biochemical assays), with attention to contaminant profiles relevant to life‑science use. It does not imply clinical/diagnostic suitability.
• What BioReagent typically entails (general guidance):
  • Controlled raw materials (peptones, agar, indicators) and consistent performance in standard microbiological QC tests.
  • Moisture content and pH of prepared medium within literature ranges; inhibition of Gram‑positive organisms and differentiation of enteric Gram‑negatives as expected.
• Item-specific specifications not provided: exact composition, pH target, performance criteria, moisture/ash, and sterility are Not specified for this item; refer to CoA/Spec Sheet.
• Stabilizers: none typically required for dehydrated media; anti‑caking agents may or may not be present depending on manufacturer—Not specified for this item; refer to CoA/Spec Sheet.
• Lot-to-lot verification (general best practice):
  • Prepare according to directions; confirm growth/inhibition with control strains (e.g., Salmonella enterica for growth and H2S production, Shigella spp. for growth without H2S, Escherichia coli for partial inhibition/color reaction, Enterococcus faecalis for inhibition) as part of in‑house QC where applicable.
• Documentation: Use the lot‑specific CoA and SDS for precise acceptance criteria and preparation details.

Reaction and Applications

As a microbiological medium, HE Agar is used for biological cultivation and differentiation rather than chemical synthesis.

Applications (literature, general):

• Selective isolation of enteric Gram‑negative pathogens from mixed specimens (e.g., stool, food, environmental swabs), emphasizing recovery of Salmonella and Shigella while inhibiting Gram‑positive flora via bile salts.
• Differential identification based on:
  • Carbohydrate fermentation (lactose/sucrose/salicin): fermenters acidify the medium, producing yellow‑orange colonies; non‑fermenters remain green to blue‑green.
  • H2S production from thiosulfate: H2S‑positive colonies form black centers due to reaction with ferric ions (e.g., many Salmonella strains).
• Utility in parallel plating strategies: Often used alongside less selective media (e.g., MacConkey, BHI) and enrichment broths for comprehensive recovery.

Practical notes (literature):

• Dry plates to remove surface moisture before inoculation to prevent colony spreading.
• Streak for isolation using aseptic technique. Incubate inverted plates at 35–37 °C for 18–24 h; extended incubation up to 48 h may enhance H2S visualization for slow producers.
• Interpretation must be confirmed biochemically (API, TSI/KIA, urea, lysine, MALDI‑TOF) or molecularly; HE Agar is presumptive.

Item-specific application text: Manufacturer Applications not provided in Product Data; none to expand.

Reaction Conditions

For this product, “reaction conditions” correspond to preparation and incubation parameters for microbiological use rather than chemical reactions.

General preparation (literature; not item‑specific):

• Medium concentration: follow the label/CoA instructions for grams per liter of purified water (exact g/L Not specified for this item).
• Hydration/dissolution: suspend dehydrated medium in cold water with stirring; heat to near boiling to dissolve completely.
• Sterilization: autoclave at 121 °C for 15 minutes (liquid cycle). Do not over‑autoclave to avoid indicator/carbohydrate degradation.
• Cooling and pouring: cool to ~45–50 °C, mix gently to distribute indicators and thiosulfate/ferric salts uniformly, then pour plates. Allow to solidify and dry surface moisture before use.
• Final pH (literature): typically ~7.5 ± 0.2 at 25 °C after sterilization.

Incubation (literature):

• Temperature: 35–37 °C for 18–24 h; some strains may benefit from up to 48 h.
• Atmosphere: ambient air; CO2 enrichment generally not required.

Quality controls (literature examples):

• Positive growth/inhibition panels often include Salmonella enterica (growth, H2S+), Shigella flexneri (growth, H2S−), Escherichia coli (partially inhibited; lactose fermenter), and Enterococcus faecalis (inhibited). Adjust to your lab’s validated strains.

Always defer to the lot‑specific CoA/Spec Sheet for precise preparation instructions for this item.

Safety and Handling

Authoritative safety information should be taken from the SDS for this product. The following is general guidance for HE Agar powders.

• GHS classification, signal word, pictograms, H‑statements: Not specified for this item; refer to CoA/Spec Sheet and SDS.
• Primary hazards (general):
  • Nuisance dust; may cause mechanical irritation to eyes, skin, and respiratory tract.
  • Dyes (e.g., acid fuchsin) can stain skin and surfaces; handle with care.
  • Avoid inhalation of powder; wet cleanup to minimize airborne dust.
• Incompatibilities (general): strong oxidizers or acids/bases may affect indicator dyes; avoid contact with reactive chemicals. Store away from moisture to prevent caking and microbial contamination of the dry medium.
• PPE: lab coat, safety glasses, disposable nitrile gloves; use a dust mask or work in a fume hood/biological safety cabinet during weighing to avoid inhalation of particulates.
• First aid (general):
  • Eyes: rinse cautiously with water for several minutes; remove contact lenses if present and easy; seek medical attention if irritation persists.
  • Skin: wash with soap and water; launder contaminated clothing.
  • Inhalation: move to fresh air; seek medical advice if symptoms develop.
  • Ingestion: rinse mouth; seek medical advice if large amounts are swallowed.
• Microbiological practice: once prepared and inoculated, plates/tubes may contain pathogens. Follow BSL‑2 practices when working with clinical or environmental samples; decontaminate by autoclaving before disposal.
• Storage per Product Data: room temperature; keep container tightly closed, dry, and protected from light. Ship normal.

Solvent Selection

This product is a dehydrated microbiological medium; solvent considerations relate to reconstitution in water rather than organic solvent selection.

• Primary solvent: high‑purity water.
  • Use distilled, deionized, or reverse‑osmosis water meeting microbiological media prep standards. Avoid residual chlorine, heavy metals, or high hardness that can interfere with indicators and selective agents.
• Dissolution behavior (literature):
  • The powder disperses in cold water and fully dissolves/clarifies upon heating to near boiling; agar sets as a gel upon cooling after sterilization.
• Practical guidance:
  • Prepare with precise mass of medium per liter of water as directed by the CoA/Spec Sheet for this item (exact g/L Not specified for this item).
  • Mix thoroughly to prevent clumping. Gentle heating while stirring improves dispersion before autoclaving.
  • Avoid overheating/extended autoclaving, which can degrade carbohydrates and dyes, altering selectivity and color response.
• Comparison to alternatives (literature context):
  • For similar applications, XLD Agar and SS Agar are common; HE Agar provides strong bile salt selectivity and robust H2S detection with a distinct color palette (green to yellow with black centers) that many users find easier to interpret for mixed enteric populations.

Storage and Reconstitution

• Storage conditions (item-specific): Room temperature (per Product Data). Keep container tightly closed, dry, and protected from light. Avoid humid environments to prevent clumping and pre‑gelation.
• Shipment: Normal (per Product Data).
• Shelf life: Not specified for this item; refer to CoA/Spec Sheet.

Reconstitution and preparation (literature; not item-specific):

• Weigh the recommended grams of dehydrated medium per liter of purified water (exact g/L Not specified for this item).
• Disperse with stirring; heat to near boiling until completely dissolved. Do not overheat.
• Sterilize by autoclaving at 121 °C for 15 minutes. Swirl gently after autoclaving to ensure uniform distribution of precipitate‑forming components.
• Cool to 45–50 °C, then pour plates under aseptic conditions.

Storage of prepared medium (literature):

• Plates: store inverted at 2–8 °C, protected from desiccation and light; use typically within 2–4 weeks, or per your validated practice.
• Broth/Deep: if prepared, store at 2–8 °C and use promptly; avoid repeated melt–solidify cycles which can degrade medium performance.

Freeze–thaw: Not applicable to the dehydrated powder. Avoid freezing prepared plates to prevent cracking and loss of gel integrity.

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

Structure and Identity

• Item type: complex, dehydrated microbiological culture medium designed for selective and differential isolation of enteric Gram‑negative bacteria (not a single chemical entity).
• Item-specific identifiers from Product Data:
  • CAS: Not specified for this item; refer to CoA/Spec Sheet.
  • Molecular formula: Not specified for this item; refer to CoA/Spec Sheet.
  • Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.
  • InChIKey / SMILES: Not applicable for a complex mixture; Not specified for this item; refer to CoA/Spec Sheet.
• Structural features (general literature description of Hektoen Enteric Agar):
  • Contains complex peptones and yeast extract (nutrients), bile salts (selective agent against Gram‑positives and some coliforms), carbohydrates (typically lactose, sucrose, salicin) for fermentation tests, sodium thiosulfate and ferric ammonium citrate for H2S detection, and pH indicators (e.g., bromothymol blue, acid fuchsin) for differential coloration; solidified with agar.
  • As a mixture of polymers (agar) and undefined biological hydrolysates (peptones), a defined 2D structure does not apply.
• Nomenclature: commonly abbreviated as HE Agar or HEA.
• SKU: H1528634; Grade: BioReagent; Research use only (per Product Data).

Synthetic Utility

Not applicable to this product type. Hektoen Enteric Agar is a complex biological culture medium and is not used as a reagent, catalyst, or building block in chemical synthesis. For chemical synthesis guidance, refer to sections focused on defined organic or inorganic reagents.

Target Specificity

This section is primarily relevant to antibodies/biorecognition reagents and does not directly apply to a culture medium.

Context for this product (literature): Hektoen Enteric Agar exhibits functional selectivity for enteric Gram‑negative bacteria due to bile salts and dye indicators. It differentially displays phenotypes of Salmonella and Shigella versus lactose/sucrose/salicin‑fermenting coliforms. However, it does not possess molecular target specificity in the sense of an antibody or ligand.