1. Outcome: DL6.5 Assess effects of micro-organisms on past and present society, and contributions of science and technology to human understanding of micro-organisms. [CP, DM, SI]
Design and conduct an investigation of the factors that influence how quickly micro-organisms break down organic matter (e.g., build a composter in a 2L plastic bottle and vary conditions such as the amount of water, soil, light, and combinations of waste products).

2. Micro-organisms and Composting: Decompose This!
Do you have a compost bin?
What are the ingredients in a compost bin?
What kinds of microbes are in compost?
How does a compost bin work?

3. What is in a compost bin?
Organic matter like vegetable peels, grass clippings, leaves, manure, water, air, etc.
It is a complex ecosystem made up of micro and macro-organisms
The main groups of microorganisms in soil are: bacteria, fungi, protozoa, and actinomycetes
In a teaspoon of bacteria there may be up to a billion bacteria!
These tiny guys are what drives decomposition and get the whole thing going for the larger players to come

4. What is in a compost bin continued…
Macro-organisms include things like worms, insects and shrews

5. What kinds of microbes are in compost?
Bacteria are the most abundant – % of all microorganisms in compost are bacteria
Two kinds of bacteria:
Aerobic – they need oxygen
Aerobic are your friends
Anaerobic – don’t need oxygen but they are the “bad neighbours” of decomposition – slow down the process and they smell!
They smell because of the waste they produce: amines & hydrogen sulfide

6. What does the bacteria do?
There are different kinds of bacteria:
Psychrophiles, mesophiles & thermophiles
Each type of bacteria have different jobs and prefer certain temperatures
Bacteria start to party and heat up the compost bin
HEAT is a by-product of decomposition

7. Heat results from the metabolic processes of microorganisms
Each group of microorganisms has a preferred temperature
So, if a pile heats up or cools down the population will adjust
Plus, organisms in the outside may be different than those in the inside
Managing a compost bin is all about keeping the temperature, water, pH, oxygen, energy and protein in a good balance

8. Also found in a compost bin:
Fungi: single or multi-celled
Fungi lack chlorophyll so they can’t make their own food
Take over in the final stages of compost
Protozoa: usually not many
Behaves the same as bacteria but is larger
Actinomycetes: part bacteria & part fungi
They prefer moderate temp.
Looks like greyish cob-webby stuff
Has a nice earthy smell – because of the waste they make

9. Check out this short video on compost
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Get out your science journals to record 4-5 facts from the video

10. What we are going to do next:
In groups of 2
We are going to prepare mini- compost bins
Come up to the front and grab supplies
And then go and sit down
Wait! for me to give you the ok to start preparing the compost bottle

11. PROCESS: measure everything you put into the compost bins, record the entire process – if you do not record you will get a ZERO!!
Step 1: cut the top of the bottle off – like the one at the front of the classroom
Step 2: label 1 bottle with soil & 1 bottle without soil
Step 3: label the back of each bottle with your names
Step 4: layer bottle 1 with soil, grass clippings, carrot/potato peels with each layer getting a mist of water STOP: just a light misting of water!
Step 5: repeat layers to the top and place top of bottle back on, leaving the cap off
Step 6: layer bottle 2 in the same manner WITHOUT soil, repeat Step 5
We will be checking our compost bins periodically over the next few weeks to see which conditions are the most favourable for microorganisms