Bacteria, Viruses, Protists & Fungi Microbiology Bacteria, Viruses, Protists & Fungi

The Story of Microbiology From the time of the Romans to the late 1800’s it was believed that life could arise spontaneously from non-living matter. Eg. Maggots on rotting meat, mould on bread 1850’s “childbed fever” is reduced when med students are forced to wash their hands. Louis Pasteur: Dispelled ‘spontaneous generation’ – Air must contain microorganisms.

The Story of Microbiology Pasteur – Solved the French wine-spoilage problem. Used heat to destroy microbes…called “pasteurization”. He then hypothesized that microbes could cause sickness… “Germ Theory”. Joseph Lister – English surgeon…sterilizes surgical instruments…survival rates increase. Late 1800’s- Robert Koch isolates and cultures bacteria responsible for anthrax in sheep and tuberculosis in humans.

Bacteria All bacteria are single celled. All are prokaryotes (no nucleus). Cell organelles are not surrounded by membranes. DNA is made of a single chromosome in a ring called a plasmid. Most reproduce asexually.

Bacteria Shapes (see handout) Coccus Bacillus Spirillum Prefixes: 1 = mono 2 = diplo Chain = strepto Cluster = staphlo

Gram Stain Stain turns bacteria violet if +ve Gram +ve: common, less pathogenic Gram –ve: typhoid, meningitis, pneumonia

Nutrition Most are Heterotrophs- -Parasites (absorb nutrients from living orgs.) OR -Saprobes (decay dead matter) Autotrophs- -Photoautotrophs- Use sunlight (cyanobacteria)

Respiration Occurs in the inner cell membrane Aerobic – Obligate Aerobes (need O2) Anaerobic – Obligate Anaerobes (no O2 needed) -Eg. Clostridium Botulinum…Carrot juice

Reproduction Asexually by binary fission. Sexually by conjugation…leads to resistance to antibiotics (see handout)

Reproduction 3. Endospores – When conditions are unfavourable the bacteria forms a protective wall and lies dormant until conditions improve. Endospores in a human lung

Helpful Bacteria Nitrogen Fixation – Converts N2 to the more useful NO3 Carbon Cycle – Decompose Matter Waste Management – Bioremediation Sewage Treatment (We produce 5 billion kg a day…bacteria break it down!)

Harmful Bacteria A small percentage are Pathogenic (disease causing) These bacteria produce deadly toxins or effects. Examples: Pneumonia, tuberculosis, botulism, Flesh Eating Disease Streptococcus Necrotizing Fasciitis Clostridium Difficile

Food Poisoning Anyone? Escherichia Coli Salmonella