Transcript Nitrogen-Fixing Bacteria

• Nitrogen-Fixing Bacteria
• Earth's atmosphere is 80% nitrogen
but plants and animals cannot use
nitrogen in gaseous state
• We require nitrogen to make
nitrogen-containing compounds like
proteins and nucleic acids
• Rhizobium are essential to the
nitrogen cycle
Legumes have lots of root nodules, filled with
these bacteria
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• Gram-Negative bacteria that perform
plant-like photosynthesis & release
oxygen as by-product (waste)
• Once classified as blue-green algae
• Now considered eubacteria, because they
lack a membrane-bound nucleus &
chloroplasts
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• “Eutrophication”: Population Bloom
of bacteria = sudden increase in # of
cyanobacteria due to high availability
of nutrients.
• After many cyanobacteria die;
decomposed by heterotrophic
bacteria.
• Consume available oxygen
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