Petri Dishes

Petri Dishes are essential vessels used for culturing and analyzing microorganisms in laboratory settings. Made from sterile plastic or glass, these shallow, lidded dishes are filled with agar or other growth media to support colony development, microbial isolation, and diagnostic testing. From clinical diagnostics to environmental sampling and research experiments, Petri dishes are a cornerstone of microbiological workflows.

Why Petri Dishes Are Essential

Accurate microbial culture relies on reliable containment and visibility—and that’s exactly what Petri dishes provide. These simple yet indispensable tools allow for controlled growth and observation of bacteria, fungi, and other microorganisms. They support critical tasks like streak plating, antibiotic testing, and morphology analysis. Sterile, stackable, and available in a variety of sizes and formats, Petri dishes ensure consistency and minimize contamination in high-throughput environments.

What Are Petri Dishes?

Petri dishes are round, flat containers with fitted lids, used to hold solid culture media such as agar. Microorganisms are inoculated onto the surface, where they grow into visible colonies for observation, identification, or quantification. Petri dishes may be made from disposable polystyrene or autoclavable glass, and they come in vented and non-vented versions to accommodate specific airflow or humidity needs. Many feature markings, grids, or stacking rings for convenience and precision.

Types of Petri Dishes

Disposable Plastic Petri Dishes

Best for: Routine culturing, diagnostic testing, and single-use applications.
These sterile, polystyrene dishes are ideal for labs that prioritize efficiency and contamination control.

Key Features:

• Gamma-sterilized or EO-sterilized for immediate use.
• Available in multiple diameters (typically 90 mm or 100 mm).
• Vented or non-vented lids to control air exchange.
• Stackable with interlocking lids or rings.
• Available with grid lines for colony counting.

Applications:

• Bacterial and fungal isolation.
• Antibiotic susceptibility testing (Kirby-Bauer).
• School or university lab work.
• Environmental or surface sampling.

Glass Petri Dishes

Best for: Reusable culturing applications requiring heat resistance or autoclaving.
Glass dishes offer excellent clarity and can withstand repeated sterilization.

Key Features:

• Made from durable borosilicate or soda lime glass.
• Suitable for dry heat or autoclave sterilization.
• Resistant to thermal shock and chemical exposure.
• Reusable for eco-conscious labs.
• May feature ground edges for improved lid fit.

Applications:

• Long-term microbial culture and observation.
• Advanced research requiring custom media.
• Fungal growth studies with extended incubation.
• Labs with in-house sterilization infrastructure.

Divided (Bisectional) Petri Dishes

Best for: Comparative culturing or dual-sample applications.
These dishes have molded dividers for simultaneous growth of two or more samples.

Key Features:

• One to three compartments per dish.
• Sterile, disposable formats.
• Reduces media usage per test.
• Prevents cross-contamination between samples.
• Compatible with standard agar types.

Applications:

• Side-by-side antibiotic efficacy testing.
• Teaching demonstrations.
• Comparative growth analysis.
• Resource-limited settings with high sample volume.

Pre-Filled (Prepared) Petri Dishes

Best for: Quick deployment in diagnostics, testing, or field use.
Pre-poured agar plates eliminate the need for in-lab media preparation.

Key Features:

• Filled with TSA, blood agar, MacConkey, SDA, etc.
• Shelf-stable with clear expiration dates.
• Lot-traceable and QC-validated.
• Individually wrapped or sleeve-packed.
• Ideal for high-throughput labs.

Applications:

• Clinical microbiology labs.
• Food and water testing.
• Pharmaceutical QC labs.
• Remote or mobile diagnostics.

When to Use Petri Dishes

• For streaking or spreading microorganisms on solid media.
• When isolating pure colonies from mixed cultures.
• During antimicrobial sensitivity testing.
• In educational demonstrations or microbial research.
• For surface sampling in environmental monitoring.

How to Use Petri Dishes

1. Ensure sterility before use (use pre-sterilized or autoclave reusable dishes).
2. Pour agar medium (or use pre-filled plates) and allow to solidify.
3. Inoculate the surface using loops, swabs, or spreaders.
4. Cover and label the dish with organism and date.
5. Incubate in an inverted position to prevent condensation drip.

Key Features of Petri Dishes

• Sterile, contamination-free designs ensure safe culturing.
• Available in disposable or reusable formats for lab flexibility.
• Vented and non-vented lids support tailored humidity and airflow control.
• Compatible with a wide range of agar types for targeted growth.
• Easy to label, stack, and store for streamlined workflow.

Benefits of Petri Dishes

Petri dishes support consistent microbial culturing across virtually all laboratory disciplines. They allow researchers and clinicians to observe, isolate, and analyze microorganisms under sterile, controlled conditions. Whether used in diagnostics, academic teaching, or industrial testing, Petri dishes are an efficient, cost-effective solution for visualizing microbial behavior and generating reliable data.

How to Choose the Right Petri Dish

• Select size based on media volume and sample type (commonly 90–100 mm).
• Choose vented vs. non-vented lids depending on humidity or gas exchange needs.
• Determine if reusable or disposable fits your lab workflow and sterilization capacity.
• Consider pre-filled options for faster deployment and reduced prep time.
• Use divided dishes for comparative studies or when conserving media.

Frequently Asked Questions (FAQs)

Q: Can I reuse plastic Petri dishes?
A: No. Disposable plastic Petri dishes are for single use only and cannot be effectively sterilized for reuse.

Q: Why are Petri dishes incubated upside down?
A: To prevent condensation from dripping onto the agar surface and disrupting microbial growth.

Q: Do Petri dishes come sterile?
A: Disposable Petri dishes are sold pre-sterilized. Glass dishes must be autoclaved before use.

Q: Are there special dishes for fungi or anaerobes?
A: While the dish itself is standard, the media and incubation method (e.g., anaerobic bag) determine suitability for specific organisms.

Q: Can Petri dishes be used outside of microbiology?
A: Yes, they are also used in plant biology, cell culture (with modifications), and general specimen display.

Related Products

• Agar & Broth Media: For filling and culturing organisms in Petri dishes.
• Inoculation Loops & Spreaders: For aseptic sample transfer onto plates.
• Anaerobic Bags & Jars: For culturing oxygen-sensitive organisms in Petri dishes.
• Incubators: To maintain optimal temperature and conditions during microbial growth.

Discover MedicalEx’s selection of high-quality Petri dishes for every microbiological need. From disposable sterile plates to reusable glassware, our options are designed for accuracy, reliability, and compatibility with your media and protocols. Shop now and take your microbial culturing to the next level—safe, sterile, and science-ready.