Lecture 2: Describing Microbial Diversity: the ... - MCD Biology

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$ Firmicutes (aka “Low G + C Gram Positive bacteria” [Bacillus, Clostridium,
Streptococcus, Staphylococcus, Lactobacillus)])
$ Actinobacteria (aka “High G + C Gram Positive bacteria” [Streptomyces,
Mycobacterium])
$ Cyanobacteria
D. Note the expansion in known bacterial diversity over the past few years!
16. Archaea:
A. Classically two groups (Crenarchaeota and Euryarchaeota) have cultivated representatives and recognition.
1) Crenarchaeota: Most cultivated types are high-temperature, but uncultivated low-temp. types are
abundant in the environment (detected by cloning rRNA and other genes – “metagenomics”)
a) Name “cren-” from the Greek for spring or fount, referring to the ostensible similarity of such organisms
to the earliest life (high temperature, using geothermal compounds for energy, e.g. H2 / S 0 -- more later)
2) Euryarchaeota: methanogens, extreme halophiles, many heterotrophs (more later):
a) Name from Greek “eury-” meaning “varied”, referring to variable
phenotypes, compared to cultivated crenarchaeota.