Book Description

BIOTECHNOLOGY 1.1 What is Biotechnology? Biotechnology is the use of microorganisms to make things that people want, often involving industrial production.

It is the controlled use of micro-organisms for human benefit.

 Not all types of microorganisms are used in biotechnology.

 Some microorganisms cause disease, others are useful to people—for example, and they play a vital role in decay and recycling of nutrients in the environment  With the arrival of new technologies such as a genetic engineering, microorganisms are becoming more useful all the time.

 The main groups are bacteria and fungi, and viruses are being more and more for genetic engineering.

 Many of the principles and some of the techniques involved in biotechnology are ancient, but fast growing.

 For example, fermentation, in which microorganisms are used, has been practiced for thousands of years to produce:  Alcoholic drinks like beer, wine tella and tej  Bread and injera  Cheese and yoghurt Traditional Approach of Biotechnology involve: 1.

Making alcoholic drinks like wine, beer, tej, tella and brewing beers, 2.

Making bread and injera 3.

Making cheese and yoghourt.

 One of the most useful microorganisms is yeast.

 When yeasts have plenty of oxygen, they respire aerobically, breaking down sugar to provide energy for their cells, and producing water and carbon dioxide as waste products.

 But yeasts are useful because they can also respire anaerobically.

 When yeast cells break down sugar in the absence of oxygen, they produce ethanol (alcohol) and carbon dioxide.

 Aerobic respiration provides more energy than anaerobic respiration, allowing yeast cells to grow and reproduce.

 However, once they exist in large numbers, yeast cells can survive for a long time in low-oxygen conditions, and will break down all the available sugar to produce ethanol.

 The anaerobic respiration of yeast is sometimes referred to as fermentation (or alcoholic fermentation).

I.

Making Alcoholic drinks 1.

Beer production  In brewery process the grain is first ‟malted (i.

e., soaked in water to germinate).

‖  During this malting period the enzyme present in the grain converts the starch to sugar.

 Then yeasts are added to convert the sugar to alcohol.

 The bitter flavor of beer is provided by the addition of hop flowers.

 In the preparation of ‟Tella ‖Gesho is added to give a bitter flavor for the ‟Tella .

‖ 2.

Tej and tela production  Tej is one of the oldest drinks in Ethiopia—it has been known since at least 400 BC.

 When we make tej we need honey, water and gesho leaf or gesho stick.

 Gesho gives a bitter edge to the brew, and wild yeasts found on the plant start the fermentation going.

 The yeasts use the honey as a source of food.

As yeast colonies grow they start to respire anaerobically, and this produces ethanol and carbon dioxide.

 The alcohol content of tej varies from about 6 to 11%.

 Tej and tella are the most commonly consumed alcoholic drinks in Ethiopia.

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