1 Useful Microbes By the end of this lesson, you will be able to…Explain how microbes are useful in the environment. Describe how microbes are used for food. Today’s Activities Remembering – microbes used in Ecology Listening – Most Wanted Microbes Demo &/ Video: Making Yoghurt Demo: Making Bread

2 What can you remember about useful microbes from previous work?What are they? What processes must the microbes be carrying out in order to be useful? When did you learn about them? Key idea: Useful Microbes What products do they make? Why are they useful? Star Thinking

3 Most Wanted Microbes! Lactobacillus acidophilus (lack-toe-bah-sill-us acid-off-ill-us): one of the bacteria gang wanted for turning milk into yogurt.

4 Most Wanted Microbes! Saccharomyces cerevisiae (sack-arrow-my-seas sair-uh-vis-ee-ay): a.k.a. baker's yeast. Wanted for making bread rise.

5 Most Wanted Microbes! Streptomyces (strep-toe-my-seas): soil bacteria wanted for making streptomycin, an antibiotic used to treat infections.

6 Most Wanted Microbes! Pseudomonas putida (sue-doe-moan-us poo-tea-dah): one of many microbes wanted for cleaning wastes from sewage water at water treatment plants.

7 Most Wanted Microbes! Escherichia coli (Esh-er-ish-e-ah coal-eye): one of many kinds of microbes that live in your gut. Wanted for helping you digest your food every day.

8 Most Wanted Microbes! Arbuscular mycorrhizas (ar-bus-que-ler my-kuh-rye-zuh): one of a soil-living fungus family. Wanted for helping crops take up nutrients from the soil.

9 Most Wanted Microbes! Bacillus thuringiensis (bah-sill-us ther-in-gee-in-sis): a.k.a "Bt", a common soil bacterium. Wanted as a natural pest-killer in gardens and on crops.

10 What will happen to the mixture by the end of the lesson?+ + What will happen to the mixture by the end of the lesson? Hot water

11 What is respiration? Respiration is….. It can be represented by this equation: carbon dioxide glucose + oxygen → water + (+ energy) How can we prove that yeast respires? What affects the respiration in yeast? How could we test this?

12 Aerobic respiration of yeast – basic methodCollect your equipment: boiling tube, beaker, thermometer, spatula, 20cm3 syringe, marker pen, stop clock, ruler 2. Half fill a beaker with warm water from the kettle and cold tap. Check the temperature is about 30ºC using the thermometer. 3. Place 5g of sugar into a boiling tube. 4. Place ½ spatula of yeast into the same boiling tube. 5. Use the syringe to measure 20ml ‘nutrient broth’. This contains minerals and salts that yeast needs to grow. Add to boiling tube with carbohydrate and yeast. Gently swirl boiling tube to mix contents. 6. Use the marker pen to draw a line to show where the yeast suspension starts (0cm). 7. Immerse your boiling tube in the beaker of hot water and start the stop clock. 8. At 5 mins intervals, measure the height of the froth with a ruler. Continue for at least 15 mins (longer if time allows)

13 Do microbes use up oxygen?Boardworks GCSE Additional Science: Biology Decay and Recycling Do microbes use up oxygen? Bacteria and fungi use oxygen when they break down organic material, leaving less for humans. carbon dioxide + water photosynthesis plant and decomposer respiration human respiration Plants grow well in soil containing certain types of micro-organisms. biomass + oxygen Teacher notes It should be highlighted to students that not all micro-organisms respire aerobically. How do micro-organisms improve plant growth?

14 Recycling and interdependenceBoardworks GCSE Additional Science: Biology Decay and Recycling Recycling and interdependence Teacher notes This statement completing activity could be used as a plenary exercise to work on interdependence. It should be highlighted that some species of bacteria respire anaerobically.

15 Boardworks GCSE Additional Science: Biology Decay and RecyclingWhat happens to nutrients? Throughout an ecosystem, energy is constantly lost by wasted heat. In contrast, nutrients are constantly recycled through the carbon cycle and the nitrogen cycle. nutrients in the soil and atmosphere energy and biomass energy and biomass microbial decomposition of dead organisms and waste

16 Boardworks GCSE Additional Science: Biology Decay and RecyclingWhat is decay? In all ecosystems, dead organisms and waste material are broken down by bacteria and fungi called decomposers. This process is decay or decomposition, and it releases nutrients back into the environment ready to be reused by other organisms. Some food chains have decaying matter as the first stage. Under what conditions will decay occur the fastest? A warm, moist, oxygen-rich environment is the most favourable for decay to occur.

17 How do humans use micro-organisms?Boardworks GCSE Additional Science: Biology Decay and Recycling How do humans use micro-organisms? The average person in the UK creates just over half a tonne of waste a year. How are micro-organisms used to break some of this down? Decomposers break down plant waste to make compost. Micro-organisms are used in sewage plants to break down human waste. Teacher notes More information about household waste is available at See the Boardworks GCSE Science (Chemistry) ‘Making Polymers’ presentation for more information on biodegradable plastic. Biodegradable plastics are broken down by micro-organisms.

18 Useful Microbes Microbes have been used for thousands of years to make products we need and enjoy. E.g. curdling milk to make the cheese on your cheeseburger and yeast to make the bread rise for your bun. Some micro-organisms play an essential role in ecosystems, such as decomposing dead plant and animal matter, thereby recycling nutrients in the soil.