Biological Sciences
Bacteria and Archaea
Bacteria and Archaea are two major domains of single-celled microorganisms. They are both prokaryotic, meaning they lack a nucleus and other membrane-bound organelles. Bacteria are found in diverse environments and play crucial roles in various ecological processes, while Archaea are known for their ability to thrive in extreme environments such as hot springs and deep-sea hydrothermal vents.
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10 Key excerpts on "Bacteria and Archaea"
No longer available |Learn more- Margaret Rodriguez(Author)
- 2016(Publication Date)
- Cengage Learning EMEA(Publisher)
Bacteria have literally been the focus of scientists’ attention for centuries, as demonstrated in the timeline in Chapter 1. Despite our fascination with these microbes, it is estimated that researchers have been able to identify only a few thousand species of prokaryotes out of the probable millions existing almost everywhere in, on, and around us. Surgical technologists and other surgical team members direct their attention to the care of the patient during surgery; however, they must have an understanding of the microbial world and how it impacts those efforts. Archaea The research into the classification of archaea is ongoing; however, after a few decades of focus on these unique ancient microbes, the data still lag far behind what has been discov- ered about the larger domain of bacteria or eubacteria, which means “true bacteria.” What is known about archaea is that these organisms are separate from both bacteria and eukaryotes. When initially identified in the 1970s, scientists created a new classification of “archaebacteria”due to the similarities in metabolism and cell structure with bacteria. The ways these organisms produced proteins from genetic encoding more closely resembled eu- karyotes. It was decided to change the classification to simply archaea to reflect their unique design characteristics and life- style. Archaea are believed to have derived from ancient an- aerobic organisms that emerged approximately 4 billion years ago and thrived in the hot, toxic, oxygen-poor atmosphere. The descendants of archaea have been isolated in modern times, mainly in extreme environmental conditions such as boiling hot springs, volcanic steam vents, salt marshes, and under glacial ice in Antarctica. Because of the exceptional circumstances of their survival in such hostile conditions, they are sometimes termed extremophiles.
eBook - PDF- Michele S. Swanson, Elizabeth A. Joyce, Rachel E. A. Horak(Authors)
- 2022(Publication Date)
- ASM Press(Publisher)
• Identify reasons why Archaea were undiscovered until the advent of molecular biology and why the diversity of extant Archaea is still being discovered. • Describe the role of methanogens in the carbon biogeochemical cycle. • Use extreme halophiles as an example to justify the statement: “The survival and growth of any microorganism in a given environment depend on its metabolic characteristics.” 358 | PART II MICROBIAL DIVERSITY Until significant amounts of information about DNA and protein sequences became available in the 1970s, there was no rational basis for assigning Bacteria or Archaea to phylogeny-based taxa. Now, the wealth of available sequence information makes the study of evolutionary relationships possible. Conservative estimates are that the number of yet-uncultivated bacterial phyla may be greater than 1,300. The analysis of microbial mats from a single site in Mexico alone produced 43 bacterial novel phyla. Environmental surveys indicate that archaea are also metabolically diverse and, consequently, ubiqui- tous and abundant. Some scientists estimate that the number of uncultivated archaeal phyla may be as high as that for bacteria. How then do we make order of this incredible prokaryotic diversity? As a guide, we will use the taxonomic classification shown in Fig. 14.2, which starts with the upper domain level (Bacteria or Archaea) and then narrows the evolu- tionary relatedness of these microbes down to the species levels. So great is the diversity even at the phylum level that we will focus on selected phylum-level clades only. Bacteria The domain Bacteria was long believed to be the largest and most complex of the two domains of anucleate microbes. However, the perceived difference might be greater than the actual one because new species and groups of Archaea continue to be discovered. The domain is further divided into several phyla (Fig. 14.3), but many more are believed to exist. The size of each bacte- rial phylum varies enormously.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- College Publishing House(Publisher)
Archaea are now recognized as a major part of Earth's life and may play roles in both the carbon cycle and the nitrogen cycle. No clear examples of archaeal pathogens or parasites are known, but they are often mutualists or commensals. One example is the methanogens that inhabit the gut of humans and ruminants, where their vast numbers aid digestion. Methanogens are used in biogas production and sewage treatment, and enzymes from extremophile archaea that can endure high temperatures and organic solvents are exploited in biotechnology. Classification New domain For much of the 20th century, prokaryotes were regarded as a single group of organisms and classified based on their biochemistry, morphology and metabolism. For example, microbiologists tried to classify microorganisms based on the structures of their cell walls, their shapes, and the substances they consume. However, a new approach was proposed in 1965, using the sequences of the genes in these organisms to work out which prokaryotes are genuinely related to each other. This approach, known as phylogenetics, is the main method used today. Archaea were first found in extreme environments, such as volcanic hot springs Archaea were first classified as a separate group of prokaryotes in 1977 by Carl Woese and George E. Fox in phylogenetic trees based on the sequences of ribosomal RNA ________________________ WORLD TECHNOLOGIES ________________________ (rRNA) genes. These two groups were originally named the Archaebacteria and Eub-acteria and treated as kingdoms or subkingdoms, which Woese and Fox termed Urkingdoms . Woese argued that this group of prokaryotes is a fundamentally different sort of life. To emphasize this difference, these two domains were later renamed Archaea and Bacteria. The word archaea comes from the Ancient Greek ἀ ρχα ῖ α, meaning ancient things.
eBook - PDF- Mary Ann Clark, Jung Choi, Matthew Douglas(Authors)
- 2018(Publication Date)
- Openstax(Publisher)
22 | PROKARYOTES: Bacteria and Archaea Figure 22.1 Certain prokaryotes can live in extreme environments such as the Morning Glory pool, a hot spring in Yellowstone National Park. The spring’s vivid blue color is from the prokaryotes that thrive in its very hot waters. (credit: modification of work by Jon Sullivan) Chapter Outline 22.1: Prokaryotic Diversity 22.2: Structure of Prokaryotes: Bacteria and Archaea 22.3: Prokaryotic Metabolism 22.4: Bacterial Diseases in Humans 22.5: Beneficial Prokaryotes Introduction In the recent past, scientists grouped living things into five kingdoms—animals, plants, fungi, protists, and prokaryotes—based on several criteria, such as the absence or presence of a nucleus and other membrane- bound organelles, the absence or presence of cell walls, multicellularity, and so on. In the late 20 th century, the pioneering work of Carl Woese and others compared sequences of small-subunit ribosomal RNA (SSU rRNA), which resulted in a more fundamental way to group organisms on Earth. Based on differences in the structure of cell membranes and in rRNA, Woese and his colleagues proposed that all life on Earth evolved along three lineages, called domains. The domain Bacteria comprises all organisms in the kingdom Bacteria, the domain Archaea comprises the rest of the prokaryotes, and the domain Eukarya comprises all eukaryotes—including organisms in the kingdoms Animalia, Plantae, Fungi, and Protista. Two of the three domains—Bacteria and Archaea—are prokaryotic. Prokaryotes were the first inhabitants on Chapter 22 | Prokaryotes: Bacteria and Archaea 589 Earth, appearing 3.5 to 3.8 billion years ago. These organisms are abundant and ubiquitous; that is, they are present everywhere.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
Archaea are now recognized as a major part of Earth's life and may play roles in both the carbon cycle and the nitrogen cycle. No clear examples of archaeal pathogens or parasites are known, but they are often mutualists or commensals. One example is the methanogens that inhabit the gut of humans and ruminants, where their vast numbers aid digestion. Methanogens are used in biogas production and sewage treatment, and enzymes from extremophile archaea that can endure high temperatures and organic solvents are exploited in biotechnology. Classification New domain For much of the 20th century, prokaryotes were regarded as a single group of organisms and classified based on their biochemistry, morphology and metabolism. For example, microbiologists tried to classify microorganisms based on the structures of their cell walls, their shapes, and the substances they consume. However, a new approach was proposed in 1965, using the sequences of the genes in these organisms to work out which prokaryotes are genuinely related to each other. This approach, known as phylogenetics, is the main method used today. ________________________ WORLD TECHNOLOGIES ________________________ Archaea were first found in extreme environments, such as volcanic hot springs. Archaea were first classified as a separate group of prokaryotes in 1977 by Carl Woese and George E. Fox in p hylogenetic trees based on the sequences of ribosomal RNA (rRNA) genes. These two groups were originally named the Archaebacteria and Eubacteria and treated as kingdoms or subkingdoms, which Woese and Fox termed Urkingdoms . Woese argued that this group of prokaryotes is a fundamentally different sort of life. To emphasize this difference, these two domains were later renamed Archaea and Bacteria. The word archaea comes from the Ancient Greek ἀ ρχα ῖ α, meaning ancient things.
- Gero Benckiser, Sylvia Schnell, Gero Benckiser, Sylvia Schnell(Authors)
- 2006(Publication Date)
- CRC Press(Publisher)
In contrast to more highly evolved eukaryotes [ Eukarya ], they are normally smaller, and they lack a cell nucleus surrounded by a membrane. There are two major prokaryotic groups also known as domains or superkingdoms (i.e., Bacteria and Archaea) . It is still under debate how the three groups, Bacteria , 82 Biodiversity in Agricultural Production Systems Archaea, and Eukarya, evolved. 83 Consequently, there is not yet a definite answer to the question of whether Prokarya and Eukarya are the two separate domains of life or whether each group, Bacteria , Archaea, and Eukarya, should be regarded as a domain. 70,114,143 To introduce the biodiversity of soil microorganisms, it makes sense to separate “soil prokary-otes” from small soil eukaryotes, since Bacteria and Archaea have similar cell sizes, a mostly unicellular lifestyle, and, in addition, both are metabolically more versatile than the eukaryotic microorganisms. It is this versatility, combined with the high, metabolically active surface area compared to their cell volume, that make soil prokaryotes so important for the geochemical cycles in terrestrial ecosystems. In fact, there are several steps in the carbon and nitrogen cycles in soils that can only be performed by prokaryotes (e.g., the biogenic synthesis of methane or the binding of molecular nitrogen from the atmosphere [nitrogen fixation]). In addition, many different soil prokaryotes are able to degrade plant residues, pesticides, and other xenobiotic compounds and thereby lay the foundation for soil fertility and sustainability of cropping systems. Due to their small size and their metabolic versatility, soil prokaryotes are perfectly equipped to colonize any imaginable ecological niche of a terrestrial ecosystem. Soils of all climatic regions are inhabited by prokaryotes, as these organisms have adapted to different concentrations of nutrients, a wide range of substrates, and ambient temperatures.
- M. Hird(Author)
- 2009(Publication Date)
- Palgrave Macmillan(Publisher)
17 Notwithstanding recent advertisements about ‘good’ bacteria in yoghurt, I am schooled in recognizing my meetings with bacteria as military encounters – invasion and defense – between my (nonbacter- ial) individual self and disease (bacteria). That is, the pathogen matrix overwhelmingly defines the parameters of animal meetings-with bac- teria. Thus my not-species meeting-with must begin by exploring bac- teria excessive to pathogen characterization. Domains Archaea and Bacteria 18 Within the domains Bacteria and Archaea, multicellular assemblages and complex life cycles with several developmental stages are common. While knowledge accumulated so far suggests a staggering diversity within these domains, the majority of bacteria are yet to be discerned, suggesting much further diversity to come. And given that bacteria exchange genes so readily, thereby creating a new ‘mix’ each time, we might reasonably argue that there are as many kinds of bacteria as there are bacteria. The quick survey provided below falls far short of express- ing the wide range of bacteria: I provide here merely a glimpse into this majority world. Scientists distinguish between organisms on the basis of several factors, such as metabolism, motility, and reproduction. Metabolism is 26 The Origins of Sociable Life: Evolution After Science Studies crucial. All organisms on earth rely upon only two sources of energy: light energy from the sun or energy derived from chemicals. One of the major differences between bacteria and animals is that many bac- teria do not ‘eat’ in the sense that we mean it: they convert light and/or chemical energy. All animals and fungi by contrast are heterotrophs – ‘living off others’, relying upon the ingestion of other organisms and their products (more on this in Chapter 7).
- Chandra, Ram(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
Chapter 13 Biodiversity of Microorganism in Different Area and its Ecological Importance Shika Jain 1 , Yogesh Franklin 1 * , Dinesh K. Kumawat 1 and B.M. Meena 2 1 Department of Food Microbiology, College of Dairy and Food Science Technology , 2 Department of Entomology, Rajasthan College of Agriculture, Maharana Pratap University of Agriculture and Technology, Udaipur, Rajasthan Introduction The overwhelming majority of biological diversity is microbial. Microorganisms span all three domains of life and are typically defined as unicellular life forms that can only be observed with a microscope, including bacteria, archaea, viruses, and many unicellular eukaryotes (e.g ., some fungi and protists). Although it might not be immediately obvious, our world is a microbial one. Biodiversity is usually discussed in terms of large organisms, but no organisms are more ubiquitous, abundant, or diverse than microorganisms. Microorganisms were the first cellular life forms and were active more than 3 billion years prior to the appearance of macro-organisms. The metabolic activities that they carried out during this time were critical for creating the conditions for the evolution of multicellular forms. The universal tree of life ( Figure 13.1 ) emphasizes this point; multicellular eukaryote is crown groups compared with the deeply rooted Bacteria and Archaea. Microbes force us to stretch our imagination about the limits of metabolic lifestyles, the geography of life, and the roles that organisms play in our lives. This ebook is exclusively for this university only. Cannot be resold/distributed. Figure 13.1 : The Universal Tree of Life Showing the Position of Archaea and Bacteria Relative to Eucarya. The placement of organisms on this phylogenetic tree is based on the analyses of SSU rRNA sequences of organisms from within each domain.
- Kumar, Har Darshan(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
Chapter 1 General Microbiology Understanding Microbes The term Microbe , or microorganism refers to any unicellular organism. Two of the three superkingdoms of life, Bacteria and Archaea , are microbial, as also are single-celled eukaryotes (protists and yeasts). Viruses are neither self-maintaining nor self-reproducing, nor even cells, yet have traditionally (though uneasily) been regarded as microbes. Viruses are in fact nanoorganisms as at least one of the dimensions of the vast majority (but not all) viruses is 100 nm or less (1 nm = 1 billionth of a meter). Macrobes is an equally loose catchall term for non-microbial multicellular life. They comprise the remainder of the Eukarya (the Animalia, Plantae). The characteristics generally supposed to constitute multicellularity are cellular differentiation and functional complementarity of different cell types. This is why macrobes are usually described as complex and ‘higher’. Microbes are simpler and ‘lower’. The border between macrobes and microbes is diffuse and vague. Many social single-celled prokaryotic and eukaryotic organisms e.g. , myxobacteria and cellular slime moulds, aggregate and behave in recognizably multicellular ways. Studies of microbes are inseparable from our most basic understandings of life, from health and disease to genetics, biochemistry, evolution, geochemistry and environment. There is nothing a human being can do from one minute to the next that does not involve cooperative arrangements with our microbial partners. Our respiration, digestion, wellbeing and overall survival all depend on microbes. All our food is produced in alliance with This ebook is exclusively for this university only. Cannot be resold/distributed. complex communities of microbes, as also are many other life-sustaining materials. Historically, the concept of prokaryote emphasized only negative organizational characteristics (the lack of nucleus and other membrane-bound organelles).
eBook - PDF- Julianne Zedalis, John Eggebrecht(Authors)
- 2018(Publication Date)
- Openstax(Publisher)
Have metabolic pathways evolved separately in Bacteria and Archaea? b. Should all methanogens be classed as Archaea in evolutionary phylogeny? c. Have methanogens evolved to live in both moderate and extreme environments? d. Did the methanogenic bacteria species also evolve as a strict anaerobe? 66. What is another question you might pose to learn more about the structural features that allow for the capture, storage, and use of free energy by archaean methanogens? 936 Chapter 22 | Prokaryotes: Bacteria and Archaea This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 a. Do archaean methanogens differ from other Archaea structurally, and if so, in what way? Is one or more of these structural differences related to these methanogens’ ability to use H 2 to oxidize CO 2 ? b. Do archaean methanogens differ from other Bacteria structurally, and if so, in what way? Is one or more of these structural differences related to these methagens’ ability to use CO 2 to oxidize H 2 ? c. Do archaean methanogens differ from other Archaea structurally, and if so, in what way? Is one or more of these structural differences related to these methagens’ ability to use CO 2 to oxidize H 2 ? d. Do archaean methanogens differ from other Archaea structurally, and if so, in what way? Is one or more of these structural differences related to these methagens’ ability to use H 2 O to oxidize H 2 ? 67. Which set of phrases related to nutritional and metabolic adaptations best fits the organisms described? a. chemoautotrophs, obligate anaerobes b. chemoautotrophs, faculative anaerobes c. chemoheterotrophs, faculative anaerobes d. chemoheterotrophs, obligate anaerobes 68. In an experiment, researchers grew plant seedlings in soils to which one of two strains of bacteria were added.
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