Lecture 4: Historical Figures Relevant to Microbial Ecology

Question 1

Louis Pasteur

Answer 1

experiment with swan neck flask

only when the flask stem was broken and exposed to the air, the environment, microorganisms, did he see growth

Question 2

Robert Koch (Kochs postulates)

Answer 2

1. the microorganism must be found in abundance in all organisms with the disease, but not in healthy individuals
2. a pure culture of the microorganism must be isolated from a diseased organism

3.the cultured microorganism must cause the same disease when infected to a healthy host

4. the microorganism must be re-isolated from the experimentally-incoculated diseased host and be shown to be identical to the original isolate.

Question 3

what did sergei winogradsky do?

Answer 3

WINOGRADSKY COLUMM

aerobic organisms
purple bacteria
green bacteria

the bottom of the column is much more anaerobic tan the top of the column. essentially, there is an oxygen gradient going down the winogradsky column, where the amount of oxygen depleting is proportional to the depth within the column.

Question 4

purple vs green bacteria in winogradsky column

where will you find each?

Answer 4

purple slightly closer to the top.

green more on the bottom

PURPLE BACTERIA
- can’t tolerate H2S at the same level that green bacteria can, but it can tolerate slightly higher levels of O2

GREEN BACTERIA
- cannot tolerate oxygen at all! but can tolerate more H2S than purple bacteria can.

Question 5

what did Martinus Beijerinck contribute?

Answer 5

Nitrogen and sulfur cycling by microbes and nitrogen fixation

• first to call himself a microbial ecologist/

Question 6

what did Alexander contribute to microbial ecology

Answer 6

• 1929 discovery of penicillin (antibiotic) as well as microbe-microbe interaction (microbial ecology)
• predicted that the use of antibiotics would give rise to antibiotic resistant strains

Question 7

what contribution did modern day Thomas Brock make?

Answer 7

isolated the thermophilic bacterium thermus aquaticus, source of heat stable DNA polymerase TAQ was used later in polymerase chain reaction (PCR) from a yellowstone hot sprong.