Reasons to Study the Bacillus Bacteria

Aerobic Spore-forming Bacteria

By Harold Eddleman, Ph. D.

Isolation and study of Bacillus species from soil, manure, and plant materials is very easy for the beginning student using only foods found in any kitchen. The various Bacillus species have many differing traits and you could have a lot of fun studying a large number of Bacillus strains which you isolated all by yourself.

The Bacillus genus contains the bacteria which are able to form spores in the presence of oxygen. Species of Bacillus are common in soils and manure, and on plant material. A bit of rich garden soil the size of a large pea is likely to contain many species. Such a lump of soil will also contain many other species of bacteria, but it is easy to kill the other bacteria with boiling water. You then have only living spores of Bacillus and Clostridium. There are a few other species of bacteria which form spores capable of survival in boiling water, but they are rare.

Since most Clostridium species will not grow in the presence of oxygen because the lack the enzymes to protect themselves from hydrogen peroxide, we will have mostly Bacillus species if we now spread a drop of the boiled soil on agar in petri dishes. That is the way to begin this research project. While other kids are working with a bunch of bacteria they got from many sources, you can isolate a dozen or hundred strains of Bacillus and look for similarities and differences and divide them into related groups.

Some Reasons to Isolate and Study Bacillus Strains

  1. Most species are harmless
  2. Easy to isolate
  3. Easy to confirm as Bacillus species
  4. Many species are economically important
  5. Bacillus is an active field of current research
  6. Genetic studies are possible
  7. It is easy to isolate phages from soil and see which strains of Bacillus they attack
  8. bacillicins can be isolated
  9. Some Bacillus strains produce antibiotics
  10. There are many experiments you can do with starch, potato, egg, and gelatin.
  11. If you don't have agar, you can use potato slices or gelatin
  12. Dozens of Bacillus strains kill insects and are becoming widely used

Insecticidal Strains of Bacillus

In my lab I have about 40 strains of Bacillus which kill insects. I just put a little on a flake of oatmeal and the larva of grain moth pests die 2 or 3 days after eating the oatflake. These pages will cover isolation and study of new insecticidal strains. Many strains kill larve of Lepidoptera pests such as the cabbage butterfly and we also have strains which kill Colorado potato beetle, mosquitos, and black flies.

Isolation of bacillusphages

Bacteriophages are viruses which grow inside bacteria and after 20 minutes to an hour, the bacteria cell falls apart releasing about 200 mature viruses. Bacillus phages are easy to isolate, by adding a bit of rich garden, field, or flowerpot soil to a culture of a Bacillus species. These pages will show you how to spread the culture lysate on a lawn of Bacillus cells so that overnight you get 1 mm sized holes containing the virus. The same methods are used to study human viruses.

There are many types of Bacillus viruses and a given virus will only attack one or a few strains. You can rapidly test your virus on many strains and try to see if you can make any sense of the results.

Testing your many Bacillus isolates.

What variations of the isolation process yield unusual strains?

Revision #1 1998 January 24

Written by Harold Eddleman, Ph. D., President, Indiana Biolab, 14045 Huff St., Palmyra IN 47164
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