Chapter 1 Strain Breeding

1. Chapter 1 Strain Breeding Strain vs. Breed physiologicalmorphological

2. Food microorganisms •Food production microorganisms – Produce new types of food • Food spoilage microorganisms –Cause spoilage of food and/or diseases

3. Use of Microorganisms • Positive • Production • Conversion • Negative • Pathogens • Spoilage

4. Five Common Characteristics of Microorganisms 1. Small volume, large surface area 2. Fast absorption and conversion 3. Rapid duplication and growth 4. Strong adaptability 5. Widespread distribution and diversified species

5. What types of microorganisms cause fermentation to occur? • Bacteria • Yeast • Mold

6. Bacteria Bacteriaare typically one-celled organisms that multiply by simple division and can be seen only with a microscope.

7. 1. Lactic acid bacteria • Lactobacillus——yugout • Streptococcus——yugout • Pediococcus—— sour pickles • Bifidobacterium——probiotics

8. Lactobacillus

9. Streptococcus

10. Pediococcus

11. Bifidobacterium

12. 2. Acetic acid bacteria • Acetobacter——vinegar

13. 3.Glutamic acid fermentative bacterium • Corynebacterium glutamicum • Brevibacterium flavum

14. Yeast Yeastsare unicellular (single-celled) fungi in which little or no mycelium develops and that ordinarily reproduce by budding. Happy Yeast

15. Saccharomyces cerevisiae

16. 1. Saccharomyces Saccharomyces cerevisiae——beer Saccharomyces ellipsoideus——wine 2.Candida Candida utilis ——SCP

17. About SCP, which is correct? A. Is a kind of protein which extracted from microbial cells. B. Is microbial cell which produced by fermentation. C. Is antibiotics secreted by microbial cells. D. Could not be regarded as food.

18. Mold (mould) Fungi that grow in the form of multicellular filaments, called hyphae. In contrast, microscopic fungi that grow as single cells are called yeasts.

19. 1. Mucro——chinese cheese 2. Rhizopus——amylase 3. Aspergillus A.niger——citric acid, glucoamylase A.oryzae——soy sauce,pasta (sweet)sauces 4. Monascus——pigment

20. Choosing Microorganisms for Industrial Microbiology – genetically stable – easy to maintain and grow – well suited for extraction or separation of desire product

21. Strain Selection • Purchase from Culture Collections • Screening of nature circumstances • Mutations • Cell biology techniques • Genetic engineering

22. Culture Collections

23. Screening of nature circumstances Most major sources of microbes for use in industrial microbiology are natural materials

24. Microbial strain collection • 1. soil slurry • 2. Enrichment • Special media • Control condition • Inhibit unwanted strain

25. 3. Isolation cultivation • Streak plate method • Pour plate method • Spread plate method

26. Streak platemethod • Bacteria are “streaked” over the surface of an agar plate so as to obtain single colonies. • It can also highlight the presence of contaminating micro-organisms.

27. This is an example of a good streak for isolation using the "four corners" method.

28. Performing a Plate Streak I

29. Performing a Plate Streak II

31. Pour platemethod • Bacteria are mixed with melted agar. • Poured into an empty plate and allowed to solidify.

33. Spread plate method • Small samples of the diluted bacteria are pipetted onto the surface of agar plates. • A sterile, bent-glass rod is then used to spread the bacteria evenly over the entire agar surface.

35. 100 Performing the Spread Plate method I

36. Keep flame away from alcohol !! 70% EtOH Performing the Spread Plate method II

38. 4. Pure cultivation • Grow only one kind of microbe • Must use aseptic technique to avoid contaminating the culture • Transfer a single colony from agar plate to liquid medium

39. 5. Productivitymeasurement • Primary screening：quantity • Secondary screening：quality

40. If I couldn’t find an ideal strain from nature, how would I do?

41. mutation • Spontaneous (natural) mutation • Induced mutation

42. Technique for inducing mutation • Physical mutagens • e.g. X-rays, g-rays, UV • Chemical mutagens • e.g. base analogs, nitrous acid, • alkylating agents

44. Mutation Via chemical or physical, and biological means

45. Advantages • Improving industrial strain to a good level • Important for 2nd metabolites • Disadvantages • Relatively minor modifications can be obtained

46. How are mutants detected by scientists? • Visible • Nutritional (auxotrophic) • What is replica plating, and how is it used to detect auxotrophic mutants? • Resistance mutations (plate on media containing the chemical)

47. Replica-plating technique to screen for mutant strains of a colony-forming microorganism.

48. Q: How would you select for L-tryptophan-producing mutant strain?

49. Cell Biology Techniques • Protoplast • Removing the cell wall with lytic enzymes in the presence of osmotic stabilizers. • In the presence of fusogenic agent such as polyethylene glycol (PEG), protoplasts are induced to fuse and form transient hybrids or diploids. • Regeneration of viable cells from the fused protoplasts.

50. Genetic Engineering Various high value added products have been produced from genetic engineering methods.