病原生物学英文课件：Physiology of Bacteria

1、Chapter 3 Physiology of Bacteria,教学目标,熟悉细菌生长繁殖的基本条件及细菌依据氧的需求的 分类。 1022 列出细菌主要产生的与医学有关的合成代谢产物， 1023 明确热原质的概念、本质、去除方法及与医学的关系。 1024 熟悉细菌常见的分解代谢产物。 1025 描述细菌个体繁殖方式及群体生长繁殖的规律。 描述培养基的概念，分类及细菌在不同培养基上主要 的生长现象，并了解细菌培养在医学上的应用。 2027 了解细菌的分类原则与层次及命名法。,Content,Growth and nutrition Growth requirement Bacterial me

2、tabolism Cultivation of bacteria Classification of bacteria,Section AGrowth and Nutrition,I can live happily if only the light and CO2 exist.,Hunting or dying, this is a question!,Growth and nutrition I,According to the different carbon source, the bacteria can be divided in to class: Autotrophs: cr

3、eature consume inorganic carbon for growth Heterotrophs: creature consume organic carbon for growth,Growth and nutrition II,The nutrition on bacterias dinner menu,Nitrogen,Phosphorus,Sulfur,Mineral,Protein and nucleic acid,ATP; nucleic acids; coenzymes (NAD; NADP),Playing important role in the circl

4、e of bacterias life,Part of the enzymes and proteins,Growth and nutrition III,Bacteria reproduce through binary fission,Time required for each reproduction cycle of different types of bacteria varies greatly,The growth of bacterial cell,Average time in vitro: 15-60mins,Average time in vivo: 5-10hour

5、s,1,2,Coliform bacilli like E.coli needed in very tiny amounts; e.g. Zn+2, Mo+2, Mn+2,Growth requirement II,Hydrogen ion concentration (pH),Neutrophiles: pH 6.08.0 Acidophiles: pH 8.5,Most bacteria exhibit a narrow optimal pH range,V. cholerae pH 8.49.2 M. Tuberculosis pH 6.56.8,The pH range of most

6、 pathogen is 7.27.6 with the exception of some bacteria,Growth requirement III,Temperature Psychrophilic forms: 1520 Mesophilic forms: 3037, including all human pathogens and opportunists Thermophilic forms: 5060,17,Growth requirement IV,Atmosphere,According to the requirement for oxygen,Obligate ae

7、robes. e.g. Pseudomonas aeruginosa Obligate anaerobes. e.g. Bacteroides fragilis Microaerophilic bacterium. e.g. Campylobacter spp, Helicobacter spp. Facultative anaerobes. e.g. Staphylococcus spp.,Oxygen is a necessity for human and some bacteria while poison for others.,Growth requirement IV,Aerot

8、olerant anaerobe anaerobic, but tolerates exposure to O2 . e.g. Clostridium perfringens Capnophilic organism requires high CO2 concentration levels. e.g. Neisseria spp.,Atmosphere,Growth requirement IV,O2- + H2O2 O2 + OH- + OH,2O2- + 2H+ O2 + H2O2 2H2O2 2H2O + O2,.,Fe3+ /Fe2+,SOD,Catalase,Poison for

9、 anerobes,The aerobes process superoxide dismutase ,catalase and peroxidase to degrade the poison,H2O2 + AH2 2H2O +A,peroxidase,Why does oxygen become poison? Lacking certain respiratory enzyme Lacking enzyme for the degradation of by-products from aerobic metabolism,Moisture & Drying,Water,Effect o

10、f drying varies,Spores,Essential for bacterial protoplasm. Hence drying is lethal to cells.,T. pallidum highly sensitive Staphylococci spp stand for months,Resistant to dessication, may survive for several decades,Osmotic effects,Radiation,Mechanical & Sonic Stress,Dr Ekta, Microbiology, GMCA,More t

11、olerant to osmotic variation due to mechanical strength of their cell walls. Exposure to X rays & gamma rays lethal May be ruptured by mechanical stress.,Section CBacterial metabolism,Bacterial metabolism I,Anabolism biosynthesis systhesizing complex molecules from simple ones requires ENERGY (ATP)

12、Catabolism - degradation breaking down complex molecules into simple ones generates ENERGY (ATP) _ Biochemical Mechanisms associated Aerobic Respiration Anaerobic Respiration Fermentation,Metabolic strategies,Metabolic strategies,Figure 13-1 Catabolism of proteins, polysaccharides, and lipids produc

13、es glucose, pyruvate, or intermediates of the tricarboxylic acid (TCA) cycle and, ultimately, energy in the form of adenosine triphosphate (ATP) or the reduced form of nicotinamide adenine dinucleotide (NADH). CoA, Coenzyme A.,Downloaded from: StudentConsult (on 14 May 2013 09:51 PM), 2005 Elsevier,

14、Figure 13-3 Fermentation of pyruvate by different microorganisms results in different end products. The clinical laboratory uses these pathways and end products as a means of distinguishing different bacteria.,Downloaded from: StudentConsult (on 14 May 2013 09:51 PM), 2005 Elsevier,Fermentation End

15、Products,Bacterial metabolism II,The test based on the products of the sugar,The test based on the other products,The test based on the products of the protein,Sugar fermentation test Voges-Proskauer (VP) test Methyl red (MR) test Citrate test,Indole test H2S test,Urealytic test,The product of the c

16、atabolic processes make it possible for us to distinguish different kinds of bacteria.,Catabolic processes,Biochemical identification,Carbohydrate utility H2S test Citrate assay,Bacterial metabolism III,The IMViC test can be used to distinguish different categories of intestinal bacilli.,I M Vi C,In

17、dole test,Methyl red (MR) test,VP test,Citrate test,E. coli,Enteric bacillus,+,+,+,+,-,-,-,-,IMViC test,Bacterial metabolism IV,A thermo-resistant toxin processed by bacteria which causes a sharp rise in the temperature of human body and which can only be eliminated under extremely high temperature

18、and pressure.,Toxins include exotoxin( Gram+) and endotoxin (LPS)( Gram-), which make the bacteria more aggressive,The anabolic process of the bacteria include its own cellular component as well as some medically important anabolites.,The anabolic process,Section D Cultivation of bacteria,Cultivatio

19、n of bacteria I,Culture medium is an artificial environment for bacteria to live on and proliferate. The medium can be classified on the basis of ingredient or physical condition.,Medium,Cultivation of bacteria II,The semi-solid medium: test for motility and short-term preservation,The liquid medium: for the enrichment of bacteria,The solid medium: for