《微生物学》课程PPT课件讲稿（英文版）Lecture 2

Lecture 2 1.5 The Historical Roots of Microbiology 1.6 Microbial Diversity and the Advent of Molecular Microbiology 2. 1 Elements of cell and viral structure 2.2 Arrangement of dna in Microbial Cells 2, 3 The tree of life

Lecture 2 • 1.5 The Historical Roots of Microbiology • 1.6 Microbial Diversity and the Advent of Molecular Microbiology • 2.1 Elements of Cell and Viral Structure • 2.2 Arrangement of DNA in Microbial Cells • 2.3 The Tree of Life

Louis pasteur -1860 Where do the microorganisms come from? Spontaneous generation? Air forced out open end (a) Nonsterile liquid Neck of flask Liquid sterilized poured into drawn out in y heating flame Heat was used to kill the microorganisms in the liquid

Louis Pasteur ~1860 Where do the microorganisms come from? Spontaneous generation? Heat was used to kill the microorganisms in the liquid

Dust and microorganisms Open trapped in bend end :(:动 Long time (b) Liquid cooled Liquid remains slowly sterile for many years When dust was prevented from reaching the sterilized liquid nor microorganisms grew in the liquid

When dust was prevented from reaching the sterilized liquid, nor microorganisms grew in the liquid

Short time Flask tipped so Microorganisms microorganism-laden grow in liquid dust contacts sterile liquid Contact with dust resulted in growth of microorganisms in the liquid -disproved spontaneous generation

Contact with dust resulted in growth of microorganisms in the liquid -disproved spontaneous generation

Robert Koch, 1870s proof that microorganisms can cause disease germ theory of disease Diseased Health anima animal Postulate 1 The suspected pathogenic Observe organism should be presentEd bo0°-● blood /tissue in all cases of the disease under the and absent from healthy animals Suspecte Red blood cell pathoger Anthrax, caused by bacillus anthracis Organism present in the blood of all diseased animals -cause or result of the disease? gure 1.12

Robert Koch, 1870s --Proof that microorganisms can cause disease -“germ theory of disease” Anthrax, caused by Bacillus anthracis Organism present in the blood of all diseased animals -cause or result of the disease? Figure 1.12

Pure culture No organisms Postulate 2 Streak agar plate The suspected organism should be grown in pure from either diseased or Colonies of suspected Inoculate health of suspected pathogen Figure 1.12

Pure culture Figure 1.12

Inoculate healthy animal with cells of suspected pati Postulate 3 Cells from a pure culture of the suspected organism should cause disease in a healthy animal Diseased animal Remove blood or tissue sample and observe by microscopy Figure 1. 12

Figure 1.12

Remove blood or tissue sample and observe by microscop Postulate 4 should be Laboratory reisolated and shown to be the same as the origina Sus Pure culture (must be as before Conclusion -specific organisms cause specific disease Koch's postulates can be extended beyond disease-causing organisms Figure 1.12

Conclusion - specific organisms cause specific disease Koch’s postulates can be extended beyond disease-causing organisms Figure 1.12

Cytoplasmic nembrane Endoplasmic reticulum Cytoplasm Nucleoid Ribosomes Ribosomes Nucleus Nucleolus 0.5 um Nuclear membrane Cytoplasm Cell wal Cytoplasmic membrane Mitochondrion Chloroplast 10