1. FOOD FROM MICROORGANISMS:
FUNGI, BACTERIA AND FERMANTATION

2. OBJECTIVES To recall the method of nutrition used by microorganisms
To know some examples of commercial exploitation of microbial metabolism

3. What is heterotroph? Most bacteria Some fungi All animals herbivores
carnivores
omnivores

4. MICROBES CARRY OUT USEFUL METABOLIC PROCESSES
Heterotrophic
Fungi -such as yeast and Fusarium- and many bacteria saprotrophic

5. The enzymes, toxic or excess products which they excrete of use to humans
Some microbes useful in food production

6. Acetobacter vinegar manufacture
Lactobacillus yoghurt and cheese production

7. ‘Ripening’ bacteria cheese production
Fusarium and mycoprotein

8. On an enormous scale in special factories
The microbes
cultured separately
added sterilised container

9. These containers fermenters or bioreactors

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11. Commercial Food Production
The fermentation processes used to grow the microbes must be economical and efficient, and methods are always being improved.

12. Cheese production is a traditional process that has been updated by the use of modern scientific techniques.
The curds are formed more quickly if the coagulation of the milk protein casein is catalysed by an enzyme.
Traditionally rennin was used, extracted from the stomach contents of calves slaughtered for meat.

13. Genetic engineers have now produced a strain of the bacterium E.
Coli which contains the gene for the enzyme chymosin.
This enzyme can be used instead of rennin to produce a cheese that is acceptable to vegetarians.

14. The second phase of cheese production also involves the action of bacteria or fungi – hard cheeses such as Stilton are formed by bacterial action from the inside, whereas soft cheeses are usually the result of fungal action from the outside.

15. The characteristic smells of strong cheeses are usually due to metabolism of fatty acids, sometimes the same as those found on human skin.
The warm, moist conditions on the feet produce and odour which the producers of Camembert cheese call ‘les pieds de dieu’ (God’s feet).
Bread and beer are produced using yeast to ferment a sugar source.

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17. Yeast from alcoholic fermentation= cattle food
Fungi form bioreactor-to produce food for humans.
Mycoprotein

18. Advantages Produced quickly Produced cheaply Taking up a little area
Controlled environment
Same quality
High protein content
Lower fat content
Easily shaped and flavoured

19. Cheese Production Pasteurised milk Starter culture “ Lactobacillus”
Milk solids-pressed to remove water.
Other bacteria and fungi- give flavour.

20. Bacteria the production of food Vinegar aerobic fermantation of alcohol

22. references http://www.biology-online.org/dictionary/Heterotroph
COMPLETE BIOLOGY FOR IGCSE