Helpful Bacteria

1. Helpful Bacteria

2. Helpful Bacteria • Most bacteria are harmless to humans, in fact some are vary useful. • Bacteria ... • Aid our digestive system. • Provide drugs and hormones. • Produce some types of food. • Provide nutrients for plants by breaking down dead material by decomposition.

3. Yoghurt • Yoghurt is made by the action of a particular bacteria (lactobacillus) on milk. • It changes milk sugar (lactose) into lactic acid. • This acid gives yoghurt its sour taste.

4. Making Yoghurt • Read the handout provided then glue it into your notebooks. • Follow the instructions on the board for making your own yoghurt from Milk!

5. Pasteurization • Pasteurizationis the process of heating liquids for the purpose of destroying bacteria. • Developed by French microbiologist Louis Pasteur in order to reduce sickness caused by drinking milk.

6. Nutrient Cycles • Decomposers live off dead plant or animal matter as well as wastes. • They break down this material into simpler chemicals and release nutrients to the soil. • Nutrient cycles show how important elements move throughout the environment.

7. Nitrogen Cycle • Nitrogen is used for making proteins, enzymes, antibodies, hormones, nucleic acids and cell membranes. • 78% of the atmosphere is made up of nitrogen. • Plants and animals cannot directly use this nitrogen as it is very unstable.

8. Nitrogen Cycle • Legumes (clover, lucerne, peas, etc) are able to use atmospheric nitrogen because they have bacteria in their roots which make the nitrogen available to the plants. • This process is called nitrogen fixation. • Nitrogen is also produced by free living bacteria in the soil.

9. Nitrogen Cycle • Other kinds of bacteria, denitrifying bacteria, convert nitrogen compounds into nitrogen gas, completing the cycle. • Without bacteria plants would not have sufficient nitrates available to grow. • Animals must eat foods containing nitrogen.

10. Nitrogen in the Atmosphere Eaten Absorbed by Plants Wastes Death Death Denitrifying Bacteria Decomposers Bacteria in Root Nodules of Legumes Free Living Bacteria in Soil Nitrate Compounds in Soil

11. Carbon Cycle • Plants use carbon dioxide during photosynthesis to make sugars and starch. • Along with animals and decomposers, plants also produce carbon dioxide during respiration. • This carbon dioxide is released into the atmosphere.

12. Carbon Dioxide in the Atmosphere Photosynthesis Respiration Respiration Respiration Eaten Animals Death Plants Death Dead Plants and animals Acted on by Decomposers

13. Practice Questions • Give 3 examples of how bacteria are beneficial to humans. • Why is milk initially heated to 85°C when making yoghurt? • Why is yoghurt generally stored at low temperature?

14. Clover Weevil Damage Waikato farmers are demanding action to stop a new pest as it continues to spread through the region. The Clover Weevil has spread steadily through the region since 1996. The Weevil eats clover, which helps fix essential nitrogen in the soil.

15. Clover Weevil Damage Without Clover, weight gain and milk yield targets are jeopardized in cattle. Farmers can combat the effects of the Weevil by fertilizing the pastures with nitrogen but this is very expensive.

16. Clover Weevil Damage • In what part of the clover is nitrogen fixed into the soil? • What type of microbe fixes nitrogen? • What type of compounds does nitrogen help build in animals? • Explain how the Clover Weevil could effect the nitrogen cycle.

17. Clover Weevil Damage • Root Nodules / Roots • Bacteria (Rhizobium) • Proteins / Amino Acids • Decrease the amount of clover in a paddock, therefore reducing the amount of available nitrogen to plants. Cattle will suffer weight gain and lower milk production as they can not create necessary proteins.