Modified Sulfite Agar - BioReagent

Cat. No.: M1528414

GRADE & PURITY BioReagent

Storage

Room temperature

Shipped In

Normal

Overview

For hydrogen sulfide production test of thermophilic spore-forming bacteria

Specifications

Specifications & Purity

BioReagent

Storage

Room temperature

Shipped In

Normal

Grade

BioReagent

Product Line

Biological Products

Application Protocols

General, literature‑based guidance is provided. Follow item‑specific instructions on the product label/CoA.

A. Plate preparation (literature/general)

1. Weigh the labeled amount of dehydrated medium per liter. Suspend in purified/deionized water with stirring.
2. Heat to dissolve; bring briefly to boiling to fully melt agar.
3. Autoclave at 121 °C for ~15 min. Cool to 45–50 °C.
4. If required by the formulation, aseptically add sterile supplements (e.g., sulfite donor, Fe(III) salt, selective agents) per method. Mix gently to avoid bubbles.
5. Pour into sterile Petri dishes. Allow to solidify. Store plates in the dark at 2–8 °C if not used immediately; equilibrate to room temperature and, for anaerobes, pre‑reduce before use (time per method).

B. Sample analysis (literature/general)

1. Prepare serial dilutions of the sample in appropriate diluent.
2. Inoculate plates by pour‑plate or spread/overlay technique to enhance FeS blackening.
3. Incubate anaerobically at 35–37 °C for 18–48 h (extend if recovering stressed cells).
4. Count black or black‑centered colonies as presumptive sulfite‑reducing organisms.
5. Confirmatory tests (as needed): aerotolerance, lactose fermentation, lecithinase, or molecular confirmation.

Item‑specific masses, supplements, and acceptance criteria: Not specified for this item; refer to CoA/Spec Sheet.

Biological Roles

This product functions as a nutrient and diagnostic matrix for microbial growth rather than having an intrinsic biological role as a single molecule.

• Functional role (literature/general): Provides carbon, nitrogen, vitamins, and minerals conducive to growth of target anaerobes while including sulfite/iron to detect sulfite‑reducing metabolism via FeS blackening. Selective agents (if included per formulation) can suppress competing flora.
• Metabolic basis of detection (literature/general): Certain Clostridia reduce sulfite (SO3²⁻) to sulfide (S²⁻) through anaerobic respiration pathways. In the presence of Fe(III), sulfide precipitates as iron(II) sulfide (FeS), giving characteristic black colonies or blackened media.
• Buffering/support: Phosphate or other buffers, when present by formulation, help maintain pH during growth; agar provides a solid support permitting colony isolation and diffusion‑limited microenvironments.
• Research context: Useful for studying spore germination, anaerobic energy metabolism, and stress tolerance in sulfite‑reducing bacteria under controlled conditions.

Item‑specific composition, buffer system, and selective agents are not provided here. For precise biological performance expectations (e.g., growth‑promotion organisms and acceptance criteria), consult the product CoA/Spec Sheet and perform in‑house method suitability tests aligned with your application.

Buffer Applications

This product is a complex agar medium, not a conventional buffering reagent.

• Buffer relevance (literature/general): Many microbiological media incorporate weak buffering (often phosphate) to maintain near‑neutral pH during incubation, but the exact buffering system and target pH depend on the specific formulation. Item‑specific buffer composition/pH: Not specified for this item; refer to CoA/Spec Sheet.
• Practical note: Do not repurpose this medium as a general laboratory buffer; use dedicated buffer systems (e.g., phosphate, HEPES) tailored to your pH and ionic‑strength needs.

Green Alternatives

While “green chemistry” frameworks apply primarily to chemical syntheses and solvents, some considerations are relevant to microbiological media.

• Solvent choice: The medium is reconstituted in water, a preferred green solvent. No organic solvents are required (literature/general).
• Ready‑to‑use vs dehydrated: Dehydrated media minimize packaging mass and refrigerated transport relative to pre‑poured plates, reducing energy use and waste in many workflows (literature/general).
• Energy usage: Autoclaving and melting agar consume energy; consolidating sterilization cycles and using efficient autoclaves can reduce footprint.
• Alternative media: Depending on the target organisms, media such as SPS (Sulfite‑Polymyxin‑Sulfadiazine) agar or TSC (Tryptose‑Sulfite‑Cycloserine) agar may offer different selectivity profiles; selection should be based on scientific performance rather than environmental impact alone (literature/general).

Tradeoffs (literature/general)

• Iron/sulfite components are integral for differentiation but can contribute to corrosion in equipment if spills occur; prompt cleanup is advised.
• Agar is a renewable marine polysaccharide; supply variability can occur seasonally. Alternative gelling agents (e.g., gellan gum) exist but may alter performance and are not direct substitutes for validated methods.

Pharmaceutical Uses

No clinical or therapeutic uses are claimed. For research use only.

Relevant roles in pharmaceutical/biotech research and manufacturing support (literature/general)

• Environmental monitoring and utilities research: Evaluation of sulfite‑reducing anaerobes in water systems or raw material studies during method development (non‑GMP research).
• Process development studies: Assessing the impact of sanitation steps or heat treatments on spore‑forming anaerobes in non‑clinical settings.
• Method suitability: Developing or verifying microbial enumeration methods targeting sulfite‑reducing organisms.

Regulatory note

• Unless explicitly stated, this product is not certified for GMP or pharmacopeial compliance. Users operating under GMP/GLP should qualify the medium via growth‑promotion testing and document supplier quality. Item‑specific compliance status: Not specified for this item; refer to CoA/Spec Sheet.

Formulation/excipient status

• Not an excipient and not intended for inclusion in drug product formulations.

Physical Properties

Item-specific physicochemical specifications are not provided for this product as it is a complex dehydrated medium.

• Physical state/appearance: Dehydrated powder; color may vary slightly by lot due to complex ingredients (literature/general). Item-specific appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Solubility: Designed to dissolve/disperse in water with heating; agar requires heating to near boiling for complete melting (literature/general). No numeric solubility value is applicable.
• pH (of prepared medium): Typically defined by formulation and tested after sterilization at 25 °C; specific target pH varies by formulation (literature/general). Item-specific pH: Not specified for this item; refer to CoA/Spec Sheet.
• Density, refractive index, logP, BP/MP: Not applicable to the dry blend; agar has a melting/gelling transition rather than a true melting point in aqueous systems (literature/general).
• Clarity/opacity (prepared): Prepared plates are generally opaque to slightly opalescent due to peptones and iron salts (literature/general).

Practical preparation properties (literature/general)

• Hydration: Gradually add the powder to purified water with vigorous mixing to avoid clumping. Heat to dissolve completely; do not scorch.
• Sterilization: Autoclave at 121 °C for ~15 min unless the formulation dictates otherwise; sensitive supplements (e.g., selective agents) are commonly filter‑sterilized and added after cooling to 45–50 °C.

Item‑specific numeric specs (water content, pH targets, fill mass, etc.): Not specified for this item; refer to CoA/Spec Sheet.

Quality & Grades

• Item-specific grade: BioReagent. This designation indicates the product is suitable for general laboratory and biological research applications, including preparation of culture media and microbiological workflows, but is not necessarily certified for clinical diagnostics, GMP manufacturing, or pharmacopeial compliance unless explicitly stated. No such claims are made here.

• What BioReagent grade implies (general):

  • Manufactured with attention to contamination control and lot consistency appropriate for research.
  • Typical vendor QC may include appearance, solubility, and growth‑promotion/inhibitory performance using defined test organisms; however, the exact QC panel varies by supplier (literature/general). Item‑specific QC tests: Not specified for this item; refer to CoA/Spec Sheet.

• Stabilizers/preservatives: Dehydrated media are inherently stable when dry; no additional stabilizer is typically required (literature/general). Item‑specific stabilizers: Not specified for this item; refer to CoA/Spec Sheet.

• UV cutoff, metal limits, peroxide content, water content: Not applicable/Not specified for this item; refer to CoA/Spec Sheet.

• Documentation and traceability:

  • For regulated research environments, retain the CoA and lot information to document medium performance.
  • For critical applications, perform in‑house growth‑promotion testing with relevant strains under your conditions.

• Fit for purpose reminder: This product is labeled For research use only (item‑specific) and should not be used for diagnostic procedures or as a medical device component.

Reaction & Applications

As a culture medium, Modified Sulfite Agar (MSA) is used in microbiological workflows rather than in chemical reactions.

Research applications (literature/general)

• Detection/enumeration of sulfite‑reducing anaerobes, particularly Clostridia. Sulfite and iron(III) in the medium allow visualization of colonies that produce sulfide; the reaction forms black iron sulfide precipitates in and around colonies.
• Food, water, and environmental microbiology research: assessment of process hygiene, spore‑forming anaerobe load, and method development/validation studies in non‑clinical research settings.
• Methodological studies: comparison of selective media, incubation atmospheres, and supplement systems for improved recovery of stressed or heat‑treated spores.

Principle of differentiation (literature/general)

• Anaerobic bacteria capable of sulfite reduction to sulfide generate blackening due to FeS precipitation when Fe(III) salt (e.g., ferric ammonium citrate) is present. Non‑sulfite‑reducers typically yield no blackening.

Practical tips (literature/general)

• Ensure strict anaerobiosis (e.g., jar with gas‑generating sachets or anaerobic chamber). Pre‑reduction of plates can enhance recovery of obligate anaerobes.
• Cool molten agar to 45–50 °C before pouring to preserve supplement activity and reduce condensation.
• For enumeration, use pour‑plate or overlay techniques to encourage blackening in the agar matrix.

Note: Specific formulation, supplement types, and concentrations for this item are not provided. Refer to the product CoA/Spec Sheet for exact preparation details.

Reaction Conditions

In place of chemical reaction conditions, the following outlines typical preparation and incubation conditions for Modified Sulfite Agar in research workflows (literature/general). Item‑specific instructions may differ; follow the product label/CoA.

Preparation (literature/general)

• Reconstitution: Suspend the specified grams of dehydrated medium per liter of purified water (per product label). Mix thoroughly to disperse.
• Dissolution: Heat with frequent stirring to boiling to ensure complete melting of agar.
• Sterilization: Autoclave at 121 °C for ~15 minutes. Some selective components are heat‑labile and should be sterilized separately by filtration and added aseptically after cooling the base to 45–50 °C.
• Pouring: Pour into sterile Petri dishes (typically 20–25 mL per 90‑mm plate). Allow to solidify; dry plates if excess surface moisture is present.

Use (literature/general)

• Incubation atmosphere: Anaerobic (e.g., anaerobic jar/chamber with validated gas mix or sachets). Pre‑reduce plates when needed by storing in anaerobic conditions prior to inoculation.
• Temperature/time: Commonly 35–37 °C for 18–48 h depending on organism load and stress state. Extend incubation up to 72 h if recovery of injured cells is under study.
• Inoculation methods: Pour‑plate or spread/overlay techniques facilitate blackening in the agar matrix for sulfite‑reducing colonies.

Quality checks (literature/general)

• Include positive control strains known to reduce sulfite and negative controls for selectivity verification.

Item‑specific medium strength (g/L), target pH, and supplement identities: Not specified for this item; refer to CoA/Spec Sheet.

Safety & Handling

Safety data for this product should be taken from the SDS for the exact catalog/lot. Item‑specific GHS details are not provided here.

• GHS classification, signal word, pictograms, H‑statements: Not specified for this item; refer to SDS.
• General hazards (literature/general):
  • Low chemical hazard expected for most dehydrated culture media; may cause mild irritation to eyes/skin/respiratory tract. Avoid generating dust/aerosols.
  • Not sterile as supplied; once hydrated and incubated with samples, plates/broths may contain viable microorganisms and must be handled as biohazardous waste under institutional biosafety procedures.
• PPE (good laboratory practice): Lab coat, gloves, safety glasses; dust mask/respirator if dusts/aerosols are generated (per risk assessment and local regulations).
• Handling advice (literature/general):
  • Prepare in a clean area; avoid contamination when adding selective supplements post‑autoclave.
  • Use heat‑resistant gloves and eye protection when pouring hot agar (burn/scald hazard).
  • Pressure hazard during autoclaving—use appropriate venting and do not overfill vessels.
• Incompatibilities: Strong oxidizers/reductants are generally incompatible with organic nutrient mixes; follow SDS guidance.
• First aid overview (literature/general):
  • Skin/eyes: Rinse with water for several minutes; remove contaminated clothing. Seek medical attention if irritation persists.
  • Inhalation: Move to fresh air; seek medical advice if symptoms occur.
  • Ingestion: Rinse mouth; do not induce vomiting; obtain medical advice if unwell.

Always consult the product SDS for authoritative safety information.

Solvent Selection

This product is a dehydrated agar medium intended to be reconstituted with water; traditional organic solvent selection does not apply.

• Primary solvent: Purified/deionized water (literature/general). Use high‑quality water to minimize inhibitory ions or chlorine residuals that may affect microbial recovery.
• Reconstitution concept (literature/general):
  • Add the specified grams per liter (per product label) to water with stirring.
  • Heat to dissolve; agar requires heating to near boiling to melt completely.
  • Adjust pH only if directed by the product instructions.
• Additives: Certain selective/differential supplements (e.g., sodium metabisulfite, ferric ammonium citrate, antibiotics) may be added aseptically after sterilization and cooling to 45–50 °C, depending on the specific Modified Sulfite Agar formulation (literature/general). Item‑specific supplement requirements: Not specified for this item; refer to CoA/Spec Sheet.

If your application requires different selectivity, consider related media (e.g., SPS or TSC agars) rather than changing solvents; selection is driven by microbiological performance, not solvent polarity.

Storage & Reconstitution

• Storage conditions (as supplied): Room temperature (item‑specific). Keep container tightly closed, dry, and protected from light and humidity. Avoid prolonged exposure to high humidity which can cause clumping and performance drift.
• Shipping: Normal (ambient) conditions (item‑specific).

Reconstitution and sterilization (literature/general)

• Reconstitution: Suspend the labeled grams per liter of powder in purified/deionized water with vigorous stirring.
• Dissolution: Heat to achieve complete agar melt. Avoid localized overheating.
• Sterilization: Autoclave at 121 °C for ~15 min unless otherwise specified. Allow to cool to 45–50 °C before adding any heat‑labile supplements aseptically.

Prepared media handling (literature/general)

• Storage of plates: Store poured plates in sealed bags or wrapped stacks to limit dehydration and oxidation of sulfite components; typical storage 2–8 °C in the dark. Use within a short window for optimal performance (follow institutional practice). Item‑specific shelf life: Not specified for this item; refer to CoA/Spec Sheet.
• Freeze–thaw: Do not freeze prepared agar plates or melted agar; freezing disrupts gel structure and performance.
• Re‑melting: If permitted by the method, melted agar can sometimes be held at 45–50 °C for several hours; repeated remelting may reduce performance—validate for your application.

Always consult the product CoA/Spec Sheet for the exact preparation mass (g/L), target pH, and any required supplements.

Structure & Identity

This product is a dehydrated, complex microbiological medium rather than a single defined chemical compound.

• Product type: Prepared culture medium base (dehydrated powder)
• Common name: Modified Sulfite Agar (MSA) — used for the detection/enumeration of sulfite‑reducing anaerobes (e.g., Clostridia) in research settings (literature/general).
• Composition nature: Complex/undefined (typically contains peptones/tryptone, yeast extract, selective/differential components such as sulfite donor and iron salt; exact composition varies by supplier; literature/general). Item‑specific formulation: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular formula: Not applicable (mixture). Not specified for this item; refer to CoA/Spec Sheet.
• Molecular weight: Not applicable (mixture). Not specified for this item; refer to CoA/Spec Sheet.
• SMILES / InChI / InChIKey: Not applicable for complex mixtures.
• Structural description (2D): As a medium, there is no single 2D structure. Functionally, the medium combines nutrient sources (nitrogen, carbon, vitamins), buffering salts, a sulfite source, iron(III) salt for H2S indication, and agar as the gelling agent (literature/general).

Notes

• Grade: BioReagent (item‑specific).
• Intended use: For research use only (item‑specific).

Synthetic Utility

Not applicable. This is a microbiological culture medium, not a synthetic organic reagent or building block.

• If your objective is chemical synthesis, refer instead to appropriate reagents, catalysts, or solvents. For biological investigations of sulfite‑reducing organisms, please see the Application Protocols and Reaction Conditions tabs for preparation and use of the medium.

Target Specificity

This product is not an antibody or molecular probe. No antigen/epitope/clone/isotype information applies.

Functional selectivity (literature/general): Modified Sulfite Agar is designed to differentially recover sulfite‑reducing anaerobes through black iron sulfide formation in and around colonies. Exact selectivity depends on the specific formulation and any added supplements. Item‑specific selectivity claims: Not specified for this item; refer to CoA/Spec Sheet.

Frequently Asked Questions

How should this product be stored?

Store at room temperature.