1. Chapter 2 Physiology of Bacteria Section 1 and section 2(study by yourself)

2. Ⅳ.the bacterial metabolic products of biosynthesis(p31) A.pyrogen:It is polysaccharide in nature,resistant to high heat even at 120 ℃ /20min ， usually use distill B.Exotoxin:secrete toxic subtance C.Endotoxin: G-,toxic component from the cell wall D.Pigments:

3. E.antibiotic:A few of bacteria produce some bactericidal or bacteristasis substances that are known as antibiotics F.Bacteriocin G.Vitamin

4. Section3 Bacterial growth and multiplication Bacteria replicate by binary fission and undergo exponential growth Number of cells124816 Exponential2 0 2 1 2 2 2 3 2 4 Definitions: Binary fission: process in which one bacterium splits into two cells. Generation time: The time it takes a population of bacteria to double in number.

5. Requirements for bacterial growth Nutritional requirements  Water  Carbon source: CO 2, glucose, sucrose, etc.

6.  Nitrogen source: N 2, nitrates, ammonia, etc  Inorganic salts: S, P, K, Mg, Ca, etc.  Growth factors: organic compounds that a cell must have for growth but cannot synthesize itself.

7. pH 1. Many bacteria grow best at neutral pH. 2.Some specialized bacteria can survive and even grow in acid or alkaline conditions.

8. Temperature Bacteria may grow at a variety of temperatures from close to freezing (pyschrophile) to near to the boiling point of water (thermophiles). Mesophiles: grow best at human body temperature (includes all human pathogens and opportunists)

9. Requirements for bacterial growth Gas requirements  Oxygen (O 2 ) Obligate aerobes: organisms that grow only in the presence of oxygen. Microaerophiles: organisms that require a low concentration of oxygen (about 4%) for growth, but higher concentrations are inhibitory. meningitides

10. Obligate anaerobes: organisms that grow only in the absence of oxygen and, in fact, are often inhibited or killed by its presence. Facultative anaerobes: organisms that grow with or without oxygen, but generally better with oxygen.  Carbon dioxide (CO 2 ): e.g., Neissria

11. Measuring bacterial mass in liquid cultures. Common methods include: Turbidity 1.The cloudiness of a liquid culture of bacteria. 2.A measure of total bacteria [live and dead]. 3.This is usually quantitated with a spectrophotometer.

12. Determination of the number of viable bacteria in a culture. Usually assessed by counting the number of colonies that grow after streaking a known volume on a plate ("plate counting" of colony forming units).

13. Bacterial growth- Standard growth curve Lag phase: The number does not increase; Metabolism is active; Lasts for a few minutes to several hours. Exponential phase / log (logarithmic) phase Divide at their most rapid rate; Size, shapes, biochemical activation, and sensitivity to antimicrobial agents of bacteria are typical. Lasts for 8-18hrs

14. Bacterial growth- Standard growth curve Stationary phase The number of live cells is constant. Spores, exotoxins, and antibiotics are produced. Decline phase The number of live cells decreases.

15. Media for laboratory studies Basal medium Enriched mediun Synthetic medium Differential medium Selective medium Anaerobic medium

16. Media for laboratory studies Liquid medium solid medium semi-solid medium triangular flask

17. inoculating loop alcohol lamp

18. Blood Agar Plate

19. Some question What is the growth curve?why? The enviromental factors effecting growth include?