Lecture 39 Flashcards
Which microbial world is largest?
The uncultivated world. Most bacteria are bacteria we have been unable to culture.
What are microbial communities? GIve an example.
A self regulating and highly stable in composition group of interacting bacterial populations. These populations are made up from individual cells of a species which proliferate.
What is microbial ecology?
The study of the interrelationships among microorganisms and their environment.
What is an enrichment culture and what are they examples of?
A culture which proved the temperature and chemical conditions in the laboratory that encourage the growth of specific groups of microbes. These are examples of mesocosms, an experimental system that simulates real life conditions as closely as possible.
What is a winogradsky column? How can one be made?
Perpetual life in a tube. Can be made by placing sediment, calcium carbonate, calcium sulphate and paper (a form of cellulose in a tube and placing water on the top
What trophic groups rely on reducing power the most?
Autotrophs.
What chemical gradients are there in a winogradsky column? What does this mean about bacteria locations?
high hydrogen sulfide at the bottom, low at the top. High sunlight and oxygen at the top, low at the bottom.
This means there will be more aerobic and phototrophic bacteria at the top and more sulfate reducing bacteria at the bottom.
Which bacteria act first in the winogradsky column? What do they do?
Cellulose digesting bacteria, these digest the cellulose and produce organic acids.
What bacteria utilises the organic acids produced by the cellulose digesting bacteria?
The sulfate reducing bacteria, these reduce sulphate to hydrogen sulfide and oxidise the organic acids to carbon dioxide monomers.
Which bacteria in a winogradsky column are phototrophic?
Cyano bacteria, purple sulfur bacteria and green sulfur bacteria.
What are the purple and green sulfur bacteria? Why is one of them higher?
Anoxygenic photoautotrophs which use carbon dioxide to produce polymers, light as an energy source and oxidation of hydrogen sulfide to reduce NADP+ to NADPH2 which is used to reduce the carbon dioxide to polymers. The purple sulfur bacteria is located higher as it has a lower hydrogen sulfide tolerance.
Which bacteria is at the top of the winogradsky column? What does it do?
Cyanobacteria, an oxygenic photoautotroph which uses the oxidation of water to produce ATP and oxygen and reduce NADP to NADPH2 which can be used to produce carbon based polymers from CO2.
How do the phototrophic bacteria in the winogradsky column avoid competition?
They accept different wavelengths of light via photosynthetic pigments with complementary absorption spectra (chlorophyll a in cyanobacteria and algae, bacteriochlorophyll in the purple and green bacteria).
What is the organisation of the bacteria in the winogradsky column and their trophic type?
from top to bottom: Cyanobacteria (oxygenic photoautotroph), colourless sulfur bacteria (chemoautotroph), purple sulfur bacteria (anoxygenic photoautotroph), green sulfur bacteria (anoxygenic photoautotroph), sulfate reducing bacteria (chemoheterotroph), cellulose degrading bacteria (chemoheterotroph).
