Listeria monocytogenes Count Plate (Gel-Type)
Catalog No.: 21121 | Brand: FSTest
36–48 hrs Standard Incubation | 1 CFU/g (mL) High Sensitivity LOD | 25 Plates Moisture-Proof Pack | 18 Months Shelf Life (2–10°C) |
The FSTest Listeria monocytogenes Count Plate (Gel-Type) is a ready-to-use, disposable microbial culture system specifically engineered for the rapid quantitative enumeration and screening of Listeria monocytogenes across food matrices.
Formulated with an advanced selective culture medium, a sensitive pH indicator, a target-specific chromogenic substrate, and cold-water-soluble absorbent gelling agents, this system supports robust growth of L. monocytogenes while suppressing competing background microflora. Specific hydrolytic enzymes produced by L. monocytogenes cleave the chromogenic substrate, which, coupled with carbohydrate fermentation, yields distinctive blue-green colonies surrounded by vibrant yellow halos. By replacing multi-step traditional agar preparation and petri dish pouring, it simplifies pathogen monitoring workflows for food processors, cold-chain distributors, and food safety inspection agencies.
High Analytical Sensitivity (1 CFU/g or mL LOD): Enables accurate detection down to 1 CFU/g (mL) of sample homogenate, fully satisfying international food safety criteria for zero-tolerance and quantitative limits.
Distinctive Dual-Reaction Chromogenic Halo: Delivers unambiguous visual discrimination where typical L. monocytogenes colonies form vivid blue-green dots surrounded by distinctive yellow halos, readily distinguishing them from non-pathogenic species.
Rapid 10-Second Solidification: Utilizes cold-water-soluble absorbent gel technology that rehydrates and solidifies within ~10 seconds of dispensing 1.0 mL sample homogenate.
Streamlined Standardized Workflow: Eliminates agar boiling, tempering, petri dish pouring, and autoclaving media prep, dramatically boosting laboratory throughput and operational consistency.
Significant Space & Waste Savings: Ultra-thin gel plate design cuts incubator shelf space by over 80% and drastically reduces biohazard disposal volume compared to conventional plastic agar dishes.
Robust Ambient Transit & Extended Shelf Life: Supports room temperature transit for up to 15 days, followed by long-term refrigerated storage at 2–10°C with an 18-month shelf life.
| Product Name | Listeria monocytogenes Count Plate (Gel-Type) |
|---|---|
| Catalog Number | 21121 |
| Target Microorganism | Listeria monocytogenes (and differential screening against L. ivanovii, L. innocua) |
| Methodology | Cold-Water-Soluble Gel Chromogenic & Sugar Fermentation Plate |
| Limit of Detection (LOD) | 1 CFU/g (or 1 CFU/mL) |
| Inoculation & Stacking Limit | 1.0 mL per plate (tested in duplicate); Maximum 20 plates per stack in incubator |
| Incubation Parameters | 36 ± 1°C for 36 – 48 hours |
| Counting Range | 15 – 150 CFU per plate |
| Pack Size & Storage | 25 plates / pack; 2–10°C refrigerated (ambient transit ≤ 15 days permitted) |
| Shelf Life | 18 months sealed; 1 month after opening package (resealed at 2–10°C) |
| Microorganism | Colony Color & Characteristic Features | Diagnostic Assessment |
|---|---|---|
| Listeria monocytogenes | Blue-green colonies surrounded by distinct yellow halos | Confirmed Positive for L. monocytogenes |
| Listeria ivanovii | Colored colonies WITHOUT yellow halos (or non-conforming halo characteristics) | Non-monocytogenes Listeria |
| Listeria innocua | Non-chromogenic / colonies lacking characteristic blue-green and yellow halo profile | Non-pathogenic Listeria species |
| Competing Background Flora | Completely inhibited or atypical morphology without target halos | Negative / Suppressed |
Optimized specifically for identifying and enumerating Listeria monocytogenes in critical food supply chains:
STEP 1 Dilution Series Weigh 25 g (or 25 mL) sample into 225 mL sterile saline/PBS (1:10 dilution). Homogenize 1–2 min, then prepare serial 10-fold dilutions (1:100, etc.) as needed. | STEP 2 Inoculate & Press Lift upper film, pipette 1.0 mL homogenate onto center, and lower film without bubbles. Press down gently with spreading plate to spread sample evenly over grid. | STEP 3 10-Sec Gelling Do not lift film after pressing. Let stand undisturbed for ~10 seconds for gel medium to solidify completely. Inoculate duplicate plates for each dilution. | STEP 4 Incubate & Count Stack ≤ 20 plates horizontally (film side up) at 36 ± 1°C for 36–48 hours. Count typical blue-green colonies with yellow halos within 15–150 CFU range. |
Target Colony Count: Select count plate(s) displaying a moderate colony density of 15 to 150 CFU. Count typical blue-green colonies surrounded by distinct yellow halos.
Quantitative Enumeration Formula: CFU/g (or CFU/mL) = Average Colony Count × Dilution Factor.
Diagnostic Rule: Colonies lacking either the blue-green pigmentation or the surrounding yellow fermentation halo are NOT Listeria monocytogenes and should not be tallied.
Adhere to strict microbiological safety protocols during routine manipulation:
Biosafety Protocol: Listeria monocytogenes is a major foodborne pathogen capable of causing listeriosis, meningitis, and pregnancy complications. Always manipulate under standard microbiological biosafety guidelines wearing disposable nitrile gloves, lab coat, and protective eyewear.
Post-Inoculation Handling: Avoid touching or pressing the central circular culture area when transferring or moving inoculated plates to ensure uncompromised gel integrity.
Light & UV Protection: Do not expose count plates to direct ultraviolet (UV) germicidal irradiation or direct sunlight. Avoid prolonged exposure to intense bench lighting.
Biohazard Waste Decontamination: All spent count plates and contaminated consumables must be autoclaved at 121°C for 15–20 minutes before disposal.
Package Components Included: 25 Listeria monocytogenes Count Plates (Gel-Type, in sealed moisture-proof packaging), User Instruction Manual.
Required Equipment (Not Provided): Stomacher/homogenizer & sterile sampling bags, constant-temperature incubator (36 ± 1°C), sterile saline (0.85% NaCl) or PBS, micropipettes (1000 µL) & sterile tips, pressing plate/spreader, analytical balance, and autoclave.
Email: service@fstestcorp.com | Website: www.fstestcorp.com
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