FSTest Lactic Acid Bacteria Count Plate (Gel-Type) (25 Tests)

Product Overview

The FSTest Lactic Acid Bacteria Count Plate (Gel-Type) is a pre-prepared, ready-to-use microbiological culture medium designed for the rapid and precise enumeration of lactic acid bacteria. This modern testing solution replaces traditional, labor-intensive agar preparation, autoclaving, and petridish pouring workflows.

By integrating a selective medium formula with dual biochemical indicators and a cold-water-soluble gelling matrix, it streamlines routine monitoring. It is an essential tool for manufacturers of dairy products, fermented beverages, functional foods, and quality assurance labs looking to verify live bacteria counts and ensure strict food safety compliance.

Product Highlights & Key Benefits

· Highly Efficient & Time-Saving: Replaces the tedious preparation of traditional MRS or specialized agar mediums. Simply uncover the film, pipette the sample directly, and incubate.

· Enzyme-Specific Visual Contrast: Utilizes an integrated chromogenic substrate targeted by the β-galactosidase enzyme produced by lactic acid bacteria. Positive colonies develop as distinctive, easy-to-count blue-green spots.

· Dual-Action pH Indicator: Features a built-in pH indicator that flags the acid-producing capability of the flora by generating a visible yellow halo around the colonies.

· Flexible Incubation Protocols: Easily adaptable to both standard and strict anaerobic strains (such as Bifidobacterium), accommodating diverse functional food formulations.

· Integrated Grid Matrix for Overload Estimation: The circular testing zone features a standard grid overlay. If colonies are too numerous to count directly, operators can calculate the average of a few squares and multiply by 28 to estimate total loads.

· Ambient Transport Advantage: Unopened test plates can be transported and stored at room temperature for up to 15 days, providing significant shipping cost benefits before long-term refrigeration storage.

Technical Principle & Color Expression

The FSTest Lactic Acid Bacteria Count Plate relies on selective growth parameters combined with specific enzymatic and pH color changes. The dry matrix consists of a selective medium, a specific chromogenic substrate, a pH indicator, and a cold-water-soluble absorbent gel.

During growth, lactic acid bacteria produce the enzyme β-galactosidase, which cleaves the pre-loaded chromogenic substrate. Simultaneously, their metabolic organic acid production lowers the localized pH environment.

Lactic Acid Bacteria → β-Galactosidase Hydrolysis (Blue-Green Colonies) + Acid Production (Yellow Halo Potential)

• Typical Positive Colonies: Appear as distinct blue-green spots, with or without a yellow halo.

Specifications & Limit of Detection

Step-by-Step Procedure

1. Serial Dilution (Sample Treatment)

·  Primary 1:10 Dilution: Weigh or measure exactly 25 g (or mL) of the sample matrix and add it into a sterile container or homogenization bag containing 225 mL of sterile water, sterile saline, or standard phosphate buffer solution. Homogenize thoroughly to obtain a 1:10 sample homogenate.

·  Subsequent Dilutions: Pipette 1 mL of the 1:10 homogenate into a test tube containing 9 mL of sterile diluent to reach a 1:100 ratio. Repeat sequentially to yield higher dilutions (1:1000, etc.) as required, making sure to use a fresh sterile pipette or tip for each individual dilution step. (Note: Original undiluted liquid samples can be evaluated directly when necessary.)

2. Inoculation Workflow

· Place the test count plates onto a sterile laboratory bench, clean bench, or biosafety cabinet, and uncover the top film layer.

· Pipette exactly 1 mL of the prepared sample solution onto the center of the circular inoculation area.

· Lower the top film carefully, executing the motion smoothly to completely avoid trapping air bubbles.

· Gently place and use a standard plate spreader on top of the film to evenly distribute the liquid sample over the circular zone. Let it stand undisturbed for at least 10 seconds until the culture medium solidifies. (Note: Do not reopen the top film after the sample has been spread.)

· Inoculate duplicate plates for each selected dilution level alongside one blank control.

3. Incubation Settings

Stack the solidified plates with their front sides facing upward and place them horizontally in the incubator. To ensure uniform thermal distribution, do not stack more than 20 plates together at one time. Program incubation parameters based on your target microflora profile (aerobic vs. anaerobic stages).

Results Determination & Final Enumeration

· Standard Enumeration: Select plates displaying a moderate colony distribution within 30–300 CFU. Multiply the counted colonies directly by the corresponding dilution factor to obtain the number of lactic acid bacteria per gram or milliliter. Report final results in CFU/g or CFU/mL.

· High-Density Overload Estimation: If the colony count is too high to count directly, select several representative small squares within the grid system. Calculate the average number of colonies per square and multiply that average by 28 to estimate the total colony count on the entire plate. Multiply this estimate by your dilution factor.

Crucial Technical & Handling Precautions

· ⚠️Physical Pressure Boundary: When retrieving culture plates from the incubator, never apply finger pressure directly onto the central circular inoculation area, as this can deform the gel structure and displace colonies.

· ⚠️Personal Protection: Operators must wear standard protective laboratory coats and disposable gloves during the entire procedure to ensure personal safety.

· ⚠️Light Shielding Notice: Do not expose plates to direct sunlight or ultraviolet (UV) light systems, and avoid prolonged exposure under strong fluorescent lighting.

· ⚠️Biosafety Disposal Protocol: Used diagnostic plates house live active microbial strains. Dispose of all count plates immediately after testing according to international biosafety waste disposal laws and sterilization standards.