12192_MicrobeScienceForGardeners

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6

Microbe Science for Gardeners

them strains. Strains are different enough to be identifiable but not different enough to warrant a species designation.

Facultative Anaerobe

All organisms require energy to live and those living in an oxygen­ rich environment. like mO!,"t animaJs and plants. use oxygen to make an energy molecule called ATP-the energy battery ofliving things.

Such organisms are called aerobic.

Some organisms, most1y microbes. live in an oxygen•poor en .. vironment and get their energy through fermentation. These are calle d anaerobic.

There is a third class of organisms�lled focultative anaerobes.

These guys will get their ener1,,y using ATP when o,")'gen is plentiful but can switch to fermencation when the oxygen level drops. Yeast is a facultative anaerobe, as are bacteria such as Staphywcoccus spp., Escherichia coli, and Salmonella.

This ability to live in both environments makes it easier for them to survive as conditions change. You might recognize E. coli as a common gut bacteria that grows ill our intestine, which is a low-oxygen environment, but it also Jives in soil and on leaves, which are high-oxygen environments.

Many gardeners make the mistake of thinking that pathogens only exist in anaerobic conditions, but all three of the above-men­ tioned bacteria can cause disease and infection.

Eukaryotes and Prokaryotes The cells of all living organisms can be divided into one of two cat­ egories: euka1")'0tiC and prokaryotic.

Eukaryotes are organisms that have euka1yotic cells, which are the basis of all multicellular orgamisms including animals, plants, and fungi. These cells have well-defined organelles inside their cells. Examples include the nucleus that contains the DNA or RNA, che endoplasmic reticulum, which is used to synthesize proteins, lipids, and steroids, and the mitoc hondtin, which produces energy.

How do you remember which is which? Simple. You are a com­ plex organism and therefore a "Youkaryote."

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