Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w...
-
date post
21-Dec-2015 -
Category
Documents
-
view
217 -
download
0
Transcript of Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w...
![Page 1: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/1.jpg)
Microbial Growth
Chapter 6
![Page 2: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/2.jpg)
Microbial Growth - refers to the # of cells, not the size of the cells
Requirements for Growth• Physical• Chemical
![Page 3: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/3.jpg)
Physical Requirements
Temperature• psychrophiles (cold loving microbes )
• range 0 C - 20 C
• mesophiles (moderate temp. loving microbes)• range 20 C - 40 C
• thermophiles (heat loving microbes)• range 40 C - 100 C
![Page 4: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/4.jpg)
pH
Most bacteria grow between pH 6.5 - pH 7.5
Very few can grow at below pH 4.0• many foods, such as sauerkraut, pickles, and cheeses
are preserved from spoilage by acids produced during fermentation
![Page 5: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/5.jpg)
Osmotic Pressure
Microbes obtain almost all their nutrients in solution from surrounding water
Tonicity• isotonic• hypertonic• hypotonic
![Page 6: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/6.jpg)
Cells
![Page 7: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/7.jpg)
Chemical Requirements
Macro & Micro Elements
C HOPKINS CaFe Mg NaCl
![Page 8: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/8.jpg)
Oxygen
Bacteria can be classified base on their oxygen requirements
![Page 9: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/9.jpg)
1. Obligate Aerobes
![Page 10: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/10.jpg)
2. Obligate Anaerobes
![Page 11: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/11.jpg)
3. Facultative Aerobes
Facultative Anaerobes
![Page 12: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/12.jpg)
4. Microaerophilic
![Page 13: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/13.jpg)
Oxygen is lethal to some organisms All organisms produce superoxide ( O2-)
Superoxide is toxic to cells (steals electrons)
Superoxide must be neutralized
![Page 14: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/14.jpg)
Superoxide dismutase
O2- + O2- + 2 H+ -------> H2O2 + O2
Hydrogen peroxide is also toxic to cells and it must be neutralized
![Page 15: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/15.jpg)
Catalase
2 H2O2 --------> 2 H2O + O2
Obligate Anaerobes lack:• Superoxide dismutase ( SOD )• Catalase
![Page 16: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/16.jpg)
Culture Media
1. Chemically Defined• the exact chemical composition is known• used to grow fastidious organisms
2. Complex Media• exact chemical composition is not known• most bacteria and fungi are grown with this
![Page 17: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/17.jpg)
Special Culture Techniques
1. Anaerobic Bacteria• a. Reducing Media• b. Anaerobic Container• c. Agar Stab• d. Agar Shake
![Page 18: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/18.jpg)
Special Culture Techniques
2. Microaerophilic Bacteria• grow best under reduced O2 levels and
increased CO2 levels
• Normal Atmosphere 21 % O2
• .3 to .03 % CO2
![Page 19: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/19.jpg)
Microaerophilic Bacteria
A. Candle Jar
16 % O2
4 % CO2
![Page 20: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/20.jpg)
Microaerophilic Bacteria
B. CO2 Generating Packet
![Page 21: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/21.jpg)
Selective Media
Inhibits the growth of some bacteria while selecting for the growth of others
Example:• Brilliant Green Agar
• dyes inhibit the growth of Gram (+) bacteria
• selects for Gram (-) bacteria
• Most G.I. Tract infections are caused by Gram (-) bacteria
![Page 22: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/22.jpg)
Selective Media EMB (Eosin Methylene Blue)
• dyes inhibit Gram (+) bacteria• selects for Gram (-) bacteria• G.I. Tract infections caused by Gram (-)
bacteria
![Page 23: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/23.jpg)
Differential Media
Differentiates between different organisms growing on the same plate
Example:• Blood Agar Plates (TSA with 5% sheep blood)
• used to differentiate different types of Streptococci
![Page 24: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/24.jpg)
Alpha Hemolytic Streptococci
Incomplete lysis of RBC’s
![Page 25: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/25.jpg)
Beta Hemolytic Streptococci
Complete lysis of RBC’s
![Page 26: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/26.jpg)
Gamma Hemolytic Streptococci
No lysis of RBC’s
![Page 27: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/27.jpg)
Selective and Differential Media
Mannitol Salt Agar• used to identify Staphylococcus aureus
Mannitol Salt Agar• High salt conc. (7.5%) inhibits most bacteria• sugar Mannitol• pH Indicator (Turns Yellow when acid)
![Page 28: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/28.jpg)
Selective and Differential Media
MacConkey’s Agar• used to identify Salmonella
MacConkey’s Agar• Bile salts and crystal violet (inhibits Gram (+)
bacteria)• lactose• pH Indicator
Many Gram (-) enteric non-pathogenic bacteria can ferment lactose, Salmonella can not
![Page 29: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/29.jpg)
Bacterial Growth - increase in the # of cells
Binary Fission
Generation Time (Doubling Time)• time required for a cell to divide• most about 1 Hr. To 3 Hrs.
• E. coli - 20 minutes
• Mycobacterium tuberculosis - 24 Hrs.
![Page 30: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/30.jpg)
Binary Fission - unchecked
E. coli - generation time of 20 min. 20 generations (about 7 hrs.)
• 1 million cells 30 generations ( about 10 hrs.)
• 1 billion cells 72 generations ( about 24 hrs.)
• 1 x 1021 • 1,000,000,000,000,000,000,000 cells
![Page 31: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/31.jpg)
Limiting factors in the environment Lack of food, water or nutrients space accumulation of metabolic wastes lack of oxygen changes in pH temperature
![Page 32: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/32.jpg)
Phases of Growth
4 Phases
1. Lag Phase 2. Log Phase 3. Stationary Phase 4. Death Phase
![Page 33: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/33.jpg)
1. Lag Phase
Bacteria are first introduced into an environment or media
Bacteria are “checking out” their surroundings
cells are very active metabolically # of cells changes very little 1 hour to several days
![Page 34: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/34.jpg)
2. Log Phase
Rapid cell growth (exponential growth) population doubles every generation microbes are sensitive to adverse conditions
• antibiotics• anti-microbial agents
![Page 35: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/35.jpg)
3. Stationary Phase Death rate = rate of reproduction cells begin to encounter environmental
stress• lack of nutrients• lack of water• not enough space• metabolic wastes• oxygen• pH
Endospores would form now
![Page 36: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/36.jpg)
4. Death Phase
Death rate > rate of reproduction Due to limiting factors in the environment
![Page 37: Microbial Growth Chapter 6. Microbial Growth - refers to the # of cells, not the size of the cells w Requirements for Growth Physical Chemical.](https://reader030.fdocuments.us/reader030/viewer/2022032521/56649d5f5503460f94a3f1b5/html5/thumbnails/37.jpg)
Enumeration of Bacteria
Turbid culture - 10 million bacterial cells per ml
Serial Dilution