Nutrient Agar Calculator

When preparing nutrient agar plates, you will need to supply enough nutrient agar in order to have a successful batch of petri dishes.

These calculators will help you determine how many dishes you can make with liquid or powder nutrient agar. You can also calculate how much agar you will need to make the desired number of plates.

Calculations are based off of products sold at Heath Scientific.

Difference between Powder and Liquid Agar

Nutrient Agar usually comes in powder or liquid form.
Powder form is usually less expensive due to shipping and storage costs; powder agar needs to be made into liquid form before it can be applied to petri dishes.

Powder Agar to Petri Dish Calculator

 

Liquid Agar to Petri Dish Calculator

 

Nutrient Agar needed Calculator

 

Where you can get these supplies

How to Grow Bacteria on Nutrient Agar Plates

Most bacteria is heterotrophic and gets energy from organic chemical compounds such as:

  • sugars
  • starch
  • protiens
  • fats

On this page we’ll be refering to heterotrophic bacteria and not autotrophic bacteria.

What Tools You’ll Need

To grow bacteria, you’ll need:

  • Nutrient Agar Plate: sterile petri dish with nutrient agar, a general purpose prepared media that grows many types of bacteria and fungi
  • Bacteria Culture: can be purchased online or collected
  • Sterile Swabs: to transfer the bacteria to the petri dish
  • Manifying Glass: to help identify the bacteria once it’s grown.

The Unseen World bacteria growing kit The Unseen World: Bacteria Culturing Kit contains all you need to grow your own bacteria.

How to Put the Bacteria on the Nutrient Agar Plate

Keep the lid over your plate to prevent contamination.

Keep the lid over your plate to prevent contamination.

Aseptic technique is the process of growing and transferring bacteria without contaminating the culture by touching or breathing on the sample.

If you have a specific bacteria culture, you can spread the bacteria on the plate using a sterile swab or innoculating loop. If you would like to collect bacteria growing on a sink, chair, table, or other areas, rub a sterile swab across the area you would like to test. Then transfer the bacteria to the nutrient agar plate by swiping the swab across the surface of the agar plate.

By holding the lid over the plate as you apply the bacteria, as in the picture here, you help prevent contamination. Avoid breathing on the swab or allowing it to make contact with other surfaces as you transfer it to the petri dish.

Where to Grow The Bacteria

Keep the bacteria out of sunlight: the UV rays may kill off the bacteria. Most bacteria grow best at normal human body temperature (98-99 degrees F). When growing bacteria, incubate at a temperature as close to this as possible. Bacteria grows slower at lower temperatures.

Some recommended places to incubate the bacteria are:

  • On top of a water heater
  • Under a warm light (but not sun light)

What to Expect

After 24-48 hrs, you may find many different-looking colonies growing on the nutrient agar plate. Each type of bacteria look a little different (color, shape, size) when they grow.

Where you can get supplies

Here are links to the various supplies you might need for growing bacteria:

Where you can get more information

If you have any questions, leave a comment down below or check out these links: