Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Industrial Biotechnology Badr Objectives Be able to introduce of
Document related concepts
no text concepts found
Transcript
Industrial Biotechnology Badr Objectives Be able to introduce of culture media and microbial requirements for the growth. Be able to prepare both a complex and selective medium. I. Introduction Microorganisms need nutrients, a source of energy and certain environmental conditions in order to grow and reproduce. In the environment, microbes have adapted to the habitats most suitable for their needs, in the laboratory, however, these requirements must be met by a culture medium. Depending on the type and combination of nutrients, different categories of media can be made. I.1 First: Some basic nutritional requirements must be added in culture media Functions carbon nitrogen Major nutrients sulphur phosphorus potassium Macronutrients magnesium calcium iron Micronutrients manganese cobalt copper, zinc, molybdenum component of organic cell materials component of proteins, nucleic acids and coenzymes component of some amino acids and coenzymes component of nucleic acids, phospholipids and coenzymes major inorganic cation, cofactor for certain enzymes important cellular cation, cofactor for many enzymes, including those involving ATP synthesis, biding of enzymes to substrates important cellular cation, cofactor of some enzymes component of cytochromes and some other conjugated cofactor for some enzymes component of vitamin B12 and coenzymes derived from it. inorganic components of special enzymes 1 Industrial Biotechnology Badr I.2 Second: Categories of culture media A culture medium is a solid or liquid preparation used to grow, transport, and store microorganisms 1. Complex media: are media that contain some ingredients of unknown composition and/or concentration; this type supplies amino acids, vitamins, growth factors, and other nutrients. 2. Synthetic (defined) media: are media in which all components and their concentrations are known. I.3 Types of Media 1. A pure culture is a population of cells arising from a single cell. 2. Selective media favor the growth of particular microorganisms and inhibit the growth of others. 3. Enriched media are supplemented by special nutrients to encourage the growth of fastidious heterotrophs. 4. Differential media distinguish between different groups of bacteria on the basis of their biological characteristics. I.4 Preparation of media I.4.1 Complex medium for yoghurt bacteria: Tryptone Glucose Extract agar (T.G.E) Material Peptone Beef extract Lactose Agar D.W 10 g 3g 5g 20 g 1000 ml Procedure: 1. Add 500 ml of distilled water to a Erlenmeyer flask. Weigh out 10 g of peptone, 3 g of beef extract, and 5 g of lactose; dissolve these in distilled water by stirring with a magnetic stirrer and complete this solution into 1000 ml. (Note: Heating may be necessary). 2. Divide this broth solution into two equal parts by adding 500 ml each to two 1000-ml Erlenmeyer flasks: Flask A: For make broth media. Dispense the broth medium (Flask A) into 15 test tubes, adding 9 ml of broth to each tube, then autoclave at 121°c, 1.5 atm for 15- 20 min. Hint: Adjust pH to 7.2. 2 Industrial Biotechnology Badr Flask B: For make solid media. Add 10 g agar (heat with stirring), then adjust pH to 7.2. Autoclave at 121°c, 1.5 atm for 15- 20 min. After sterilization dispense the nutrient medium into Petri dishes. Fig. 1.1 Preparation of media I.4.2 Yoghurt bacteria Lactobacillus delbrueckii subsp. Bulgaricus & Streptococcus Thermophilus . salivarius subsp. I.4.2.1 Lactobacillus delbrueckii subsp. Bulgaricus Lactobacillus delbrueckii are gram-positive, rod with rounded ends 0.5-0.8 by about 2.0-9.0 µ , occurring singly and short chains. Facultatively anaerobic, homofermentative lactic acid bacterium, plays an important role in the dairy industry because of its efficient and reliable utilization of milk constituents, mainly lactose and caseins, and its good resistance to low pH. 1.4.2.2 Streptococcus salivarius subsp. Thermophilus Streptococcus thermophilus are gram-positive, spherical to ovoid cells 0.7-0.9 mm in diameter, in pairs to long chains. Facultative anaerobe that belongs to a group of lactic acid bacteria that convert lactose to lactic acid and acetaldehyde. Acid is produced from fructose , glucose , mannose ,and lactose. Many ferment sucrose and some ferment maltose weakly. 3 Industrial Biotechnology Badr 1.4.3 Selective media for Lactobacillus delbrueckii subsp. Bulgaricus & Streptococcus salivarius subsp. Thermophilus . 1.4.3.1 Elliker Agar Material Tryptone Yeast extract Gelatin Dextrose Lactose Sucrose Sodium chloride Sodium acetate Ascorbic acid Agar D.W 20 g 5g 2.5 g 5g 5g 5g 4g 1.5 g 0.5 g 15 g 1000 ml Hint: Adjust pH to 6.8. The mixture was then autoclaved, and upon cooling, it was poured into empty petri dishes and solidified. 1.4.3.2 M17 Liquid Media Material 5g Phytone peptone 5g Polypeptone 5g Yeast extract 2.5 g Beef extract 5g Lactose 0.5 g Ascorbic acid 19 g 2-Disodium glycerophosphate 1 ml MgSO4·7H2O (1.0 M) Glass-distilled water 1000 ml Hint: Adjust pH to 7.1. The mixture was then autoclaved, and upon cooling, it was poured into empty test tubes when needed. 4
