BIOS 2150 Microbiology Tuesday 9/25/18
For Review:
What is the role of oxygen in bacterial metabolism?
What about carbon?
Explain how a low pH affects bacterial metabolism. Shuts down metabolism
because it ruins the enzymes that the bacteria need to survive.
Bacteria have varying oxygen requirements. Which category describes those
that would grow deep in the soil?
o Obligate aerobic- requires oxygen for energy production as an
electron acceptor
o Facultative anaerobic- can thrive in oxygen but can also use another
electron acceptor if oxygen is not available. Can go with or without
oxygen
o Obligate anaerobic- oxygen is harmful to them because they don’t
have catalase and SOD
Symbiosis (Section 4.1 Page 152)
Close association between two unlike organisms that is beneficial to one or
both of them.
1. Parasitism
The interaction is between a host and a parasite
The parasite lives on the host, at the expense of the host. The host is giving
something to the parasite that it needs to survive. The host is harmed by the
interaction. The parasite may end up killing off the host but its not trying
to… just happens to weaken it enough that it can survive
Examples: Cedar-apple rust; powdery mildew; heartworm in a dissected dog
heart
2. Mutualism
An interaction where both organisms benefit each other
These two organisms aren’t going to do as well if they live apart
Examples: protozoa that live in the digestive tract of termites; lichen: an
algae and fungus living together; cattle and microbes (protists and bacteria)
in their stomach; bacteria that humans carry in us (normal flora)
(Chapter 26 page 1051 Key Terms:
o Competitive exclusion: when you have two organisms competing for
the same resources, one of them is going to win and one will lose
o Bacteriosins: chemicals that bacteria manufacture to kill off other
bacteria. Once they lay down bacteriosins other bacteria have a much
harder time establishing themselves.
3. Commensalism
An interaction where one organism benefits and the host is not affected
Some normal skin flora
Fungus or lichens on tree bark
Dust mites in your house
1
For Review:
What is the role of oxygen in bacterial metabolism?
What about carbon?
Explain how a low pH affects bacterial metabolism. Shuts down metabolism
because it ruins the enzymes that the bacteria need to survive.
Bacteria have varying oxygen requirements. Which category describes those
that would grow deep in the soil?
o Obligate aerobic- requires oxygen for energy production as an
electron acceptor
o Facultative anaerobic- can thrive in oxygen but can also use another
electron acceptor if oxygen is not available. Can go with or without
oxygen
o Obligate anaerobic- oxygen is harmful to them because they don’t
have catalase and SOD
Symbiosis (Section 4.1 Page 152)
Close association between two unlike organisms that is beneficial to one or
both of them.
1. Parasitism
The interaction is between a host and a parasite
The parasite lives on the host, at the expense of the host. The host is giving
something to the parasite that it needs to survive. The host is harmed by the
interaction. The parasite may end up killing off the host but its not trying
to… just happens to weaken it enough that it can survive
Examples: Cedar-apple rust; powdery mildew; heartworm in a dissected dog
heart
2. Mutualism
An interaction where both organisms benefit each other
These two organisms aren’t going to do as well if they live apart
Examples: protozoa that live in the digestive tract of termites; lichen: an
algae and fungus living together; cattle and microbes (protists and bacteria)
in their stomach; bacteria that humans carry in us (normal flora)
(Chapter 26 page 1051 Key Terms:
o Competitive exclusion: when you have two organisms competing for
the same resources, one of them is going to win and one will lose
o Bacteriosins: chemicals that bacteria manufacture to kill off other
bacteria. Once they lay down bacteriosins other bacteria have a much
harder time establishing themselves.
3. Commensalism
An interaction where one organism benefits and the host is not affected
Some normal skin flora
Fungus or lichens on tree bark
Dust mites in your house
1
