21 Notes - Topic 21 Fundamentals of Microbiology...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Topic 21 Fundamentals of Microbiology (Biology 140) Course notes Dr. Josh D. Neufeld Learning Objectives: To continue exploring the diversity of the Archaea, within the Crenarchaeota. Crenarchaeota The cultured examples of crenarchaeotes are almost all obligate anaerobes, and they are either chemoorganotrophs or chemolithotrophs (Table 19.8). These organisms include some of the most hyperthermophilic organisms known (Table 19.9). Indeed, most of the crenarchaeotes that have been cultured are hyperthermophiles, and they have been isolated from diverse habitats (Table 19.7). One fascinating symbiosis (parasitism) of note exists between the euryarchaeote Igniococcus and the crenarchaeote Nanoarchaeum. Both have outstanding features and characteristics and this unusual interaction will be covered in class and in the first passage of textbook 19.7 (including Figure 19.14). Recent research has demonstrated that a mesophilic group of crenarchaeotes exists in aquatic (marine, freshwater) and terrestrial (soil) environments and that these organisms likely account for most of the autotrophic ammonia oxidation. One mesophilic crenarchaeote has been cultured and had its genome sequenced (Nitrosopumulis maritimus strain SCM1). These findings are surprising because for approximately 100 years (since Winogradsky!), microbiologists had believed that only the Proteobacteria were responsible for autotrophic ammonia oxidation. The mesophilic Crenarchaeota are highly divergent from the other Crenarchaeota and are currently being reclassified within the Archaea to form their own division, called the Thaumarchaeota. In addition to these organisms, environmental sampling has revealed that there are crenarchaeotes living in some of the coldest environments on Earth, such as the Antarctic (Figure 19.22, Table 19.7). These organisms are known only from their 16S rRNA sequences, however, and nothing is known of their physiology or biochemistry because they have not yet been cultured. ...
View Full Document

This note was uploaded on 12/23/2011 for the course BIOL 140 taught by Professor Dr.joshneufeld during the Fall '10 term at Waterloo.

Ask a homework question - tutors are online