Agar Plates 10 PCA

Quick Answer: Agar Plates 10 PCA is a pack of ten ready-poured Petri plates of plate count agar (PCA), a general nutrient medium used to count viable aerobic bacteria in water, milk, food and environmental samples by the plate count method.

What Plate Count Agar Is For

Plate count agar, also called standard methods agar, is a non-selective medium, typically tryptone, yeast extract and glucose solidified with agar. It supports the growth of a wide range of bacteria without favouring any one group, which is exactly what a total viable count needs. Each colony that grows is taken to have started from a single cell or clump, so counting colonies and correcting for dilution gives colony-forming units (CFU) per millilitre or per gram of sample.

Because the plates arrive ready-poured, a class can go straight to the practical without preparing and sterilising medium. Samples are diluted in steps, usually tenfold, and a measured volume of each dilution is spread over the agar surface. After incubation, plates with a countable number of colonies, commonly 30 to 300 in standard methods, are used for the calculation.

The title states ten plates per pack. The image file linked to this listing mentions PDA (potato dextrose agar), which is a medium for fungi, so confirm that the plates supplied are PCA before ordering, as the two media serve different purposes.

Specifications

Practical Uses

• Total viable counts of raw and pasteurised milk in food science practicals
• Comparing bacterial numbers on surfaces before and after cleaning
• Water quality investigations using diluted samples
• Teaching serial dilution and colony counting technique

Storage, Incubation and Disposal

• Store unopened plates in a refrigerator, lid side down, and use them before the date on the label.
• Let plates reach room temperature and dry any surface moisture before spreading samples.
• After inoculation, tape the lid in a few places and incubate upside down; in schools, do not open plates once colonies have grown.
• Sterilise used plates, for example by autoclaving, before disposal in line with local rules.

Why Choose LabEquip

Microbiology tutors, food science teachers and college labs use ready-poured plates to save preparation time and keep a practical on schedule. LabEquip lists them in General Lab Products; the educational incubator holds plates at a set temperature, and reusable borosilicate glass Petri dishes suit labs that pour their own media.

Frequently Asked Questions

What is plate count agar used for?

It is used to estimate the total number of viable aerobic bacteria in a sample. Because it is non-selective, most common bacteria grow on it, so the colony count reflects the overall microbial load rather than one group.

Is PCA the same as nutrient agar?

Both are general-purpose media, but PCA has a defined recipe with tryptone, yeast extract and glucose developed for standard counting methods. Nutrient agar has a slightly different recipe and is often used for general culture work.

Why are plates incubated upside down?

Condensation forms on the lid during incubation. With the plate inverted, droplets stay on the lid instead of dripping onto the agar, where they would spread colonies and spoil the count.

How do I calculate CFU per millilitre?

Count the colonies on a plate within the countable range, divide by the volume plated in millilitres and multiply by the dilution factor. For example, 150 colonies from 0.1 ml of a 1 in 1000 dilution gives 1.5 million CFU per ml.

Can fungi grow on PCA?

Some yeasts and moulds can grow on it, but the medium is designed for bacterial counts. Potato dextrose agar or another fungal medium is the usual choice when yeasts and moulds are the target.

What safety rules apply to school microbiology with these plates?

Use aseptic technique, seal lids with tape, incubate at temperatures that do not favour human pathogens, never open plates after incubation, and sterilise all cultures before disposal. Follow your school’s microbiology guidance.

Last Updated: September 2026