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:

Gram Staining Bacteria

grain staining bacteriaBacteria can be differentiated based on how they react to a a procedure of dying cells called Gram stain. Bacteria are divided into a group that turns purple (gram positive) and a group that turns red (gram negative). Bacteria that are gram (+) include Staphylococcs, Streptococcus, Bacillus and Micrococcus. Gram (-) bacteria include E.coli and Salmonella. The Gram staining procedure is as follows:

Gram Staining Bacteria Procedure

1.Place a drop of distilled water on a slide and, using a swab or inoculating loop, mix the bacteria with the water an smear the mixture on the slide. The mixture will appear cloudy. Using a flame, heat fix the bacteria to the slide (pass the slide through the flame a few times to “dry” the bacteria and affix it to the slide).

2. Using a dropper, add crystal violet to the slide. Let stand for 1 minute.

3. Add iodine to the slide. Let stand for 3 minutes.

4. Decolorize the sample with alcohol. Let stand for 30 seconds.

5. Counter stain the sample with safranin. Let stand 1-2 minutes. Using a dropper, rinse with distilled water.

Gram Staining Results

Gram positive bacteria will appear purple under the microscope. They have a single, thick cell wall. The crystal violet and iodine combine to attach to this wall. The decolorizer (alcohol) dehydrates the cell wall, causing the pores to close, trapping the stain inside. the safranin added in the final step, does not penetrate the wall.

Gram negative bacteria will appear red. The have a cell wall and additional thin layers of fatty sugars. The decolorizer easily penetrates these thin sugar layers, washing away the crystal violet – iodine chemical (purple color). The safranin in the last step attaches to these layers and appears red.

Formula For Successfully Hatching Chicken Eggs

chicken eggs

No other bird in the world has a larger population than the chicken, chickens are used mostly as a food source as well as for their eggs.

Following these steps will help ensure you have success in hatching your chicken eggs.

How to Hatch a Chicken Egg

Succesfully hatching chicken eggs is a 21 day process. By using an automatic egg turner and still air incubator, the process can be very simple and successful.

Day 1

Place the chicken egg incubator on a level surface, fill trough with water, place automatic egg turner in (if you have one), adjust temperature to 97 degrees F and place the chicken eggs small end down in the turner.

Day 2-3

Monitor temperature and water level. During the chicken egg hatching process, leave the chicken egg incubator closed except for adding water.

Day 4

Remove the red plugs for ventilation and check water level.

Day 5-13

Monitor temperature and water.

Day 14

Chick development and metabolism during the incubation may cause the temperature to rise. The temperature may need to be reduced. Monitor this until day 18.

Day 15-17

Monitor temperature and water trough

Day 18

The eggs are getting close to hatching. Remove chicken eggs from turner and the turner from the incubator. Place chicken eggs on the wire tray and fill the large and small trough with water. Raise the temperature to 98 degrees.

Day 19-21

Maintain the temperature at 98 degrees. Allow the chicks to hatch and dry in the incubator.

Some chicken eggs may hatch slower. Leave them in the incubator for 2 more days. Supply heat lamp, chick feed and water for the chicks.

Where you can get Supplies

If you are looking for eggs you can hatch, you should check with local farms. Getting eggs off of Ebay or other online locations usually has a 50% hatch rate at best (this is due to shipping).

Have Questions or Comments?

If you’ve found great places to buy hatching chicken eggs, or have a question or comment- let us know below.

Care Instructions for Pet Crayfish

crayfishCrayfish are marvelous classroom organisms. They are exciting and easy to care for. Through close observation, students can learn interesting details about animal structures while developing sensitivity to the needs of living organisms.


Crayfish are also known as crawfish, crawdads, mudbugs, and yabbies; they resemble and are related to lobsters. Crayfish most commonly live in freshwater, only a few have the ability to survive in salt water. There are over 500 different species of crawfish in the world and more than half of them are located in North America. Specifically, Louisiana produces 90% of the world’s crayfish for consumption as food.


To keep your pet crayfish comfortable you will need to keep it in a freshwater aquarium, a fish tank will work just fine. Make sure to cover any holes in the lid of the tank to keep your crayfish from escaping. Feeding your crayfish is simple; many common fish foods will work. Pet crayfish will eat shrimp pellets, vegetables, fish food, algae wafers, goldfish, and minnows. Be careful which fish, if any, you put in the aquarium with your pet crawdad because they will attack and eat fish if they feel threatened or if they appear to be an easy snack. When using a prepared food, do not overfeed. The excess food will spoil the water.

Crayfish from the wild may have mud on their swimmerettes. The crayfish need to be purged (placed in clean, dechlorinated water) to remove the mud. Depending on how much mud is present, several water changes may be necessary.

Crayfish like to have a place to hide. The crayfish will molt, shed it’s exoskeleton. During the few hours after the molt, the crayfish has a soft exoskeleton and is vulnerable to predators. The larger the crayfish grows, the longer the time is in between molts. Crayfish have gills for breathing underwater, but can also breathe air.

Geode Rock Formations

What is a Geode Rock Formation?

Geodes are a great way to view and learn about the formation of rocks. They occur in sedimentary as well as some volcanic rocks too. These geological rock formations are most commonly limestone on the outside, while the inside is hollow and full of quartz crystals. If there is no air pocket in the formation it is called a nodule instead of a geode.

How Do Geodes Form?

A geode starts off as a bubble or a void left by an animal burrow, tree root, or something else. Water is trapped inside of the void, which contains silica precipitation that has other minerals or elements present in it such as calcite, iron or manganese. The basic crystals of a geode are made of quartz (silicon dioxide) and are colored based on the contents of the surrounding soil. Over thousands of years different layers of silica precipitation cool and create different layers of crystals. There is no way to tell what is on the inside of a geode without cracking it open. You can view the process of cracking open a geode below.

How to open a Geode

This video demonstration shows cracking open a Geode with a pipe cutter.

If you want to learn how to break open your own geode, check out this page at the Geode Gallery.

Where you can find Geodes

Geodes are found in areas where there had been:

  • Volcanic activity at one point.
  • Weathering had taken place that allowed the accumulation of minerals and organic substance.

Over at The Geode Guys, they have a list of some locations that are known to have geodes.

Where you can Purchase Geodes

Heath Scientific can provide you with a solid geode or crack it open for you.