Biological Sciences
Bacteria
Bacteria are single-celled microorganisms that can be found in various environments, including soil, water, and living organisms. They have diverse shapes and sizes and can be beneficial, such as aiding in digestion and nutrient cycling, or harmful, causing diseases. Bacteria play a crucial role in ecosystems and have significant impacts on human health and industry.
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9 Key excerpts on "Bacteria"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Research World(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 1 Bacteria Bacteria are a large domain of single-celled, prokaryote microorganisms. Typically a few micrometres in length, Bacteria have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria are ubiquitous in every habitat on Earth, growing in soil, acidic hot springs, radioactive waste, water, and deep in the Earth's crust, as well as in organic matter and the live bodies of plants and animals. There are typically 40 million Bacterial cells in a gram of soil and a million Bacterial cells in a millilitre of fresh water; in all, there are approximately five nonillion (5×10 30 ) Bacteria on Earth, forming a biomass on Earth, which exceeds that of all plants and animals. Bacteria are vital in recycling nutrients, with many steps in nutrient cycles depending on these organisms, such as the fixation of nitrogen from the atmosphere and putrefaction. However, most Bacteria have not been characterised, and only about half of the phyla of Bacteria have species that can be grown in the laboratory. The study of Bacteria is known as bacteriology, a branch of microbiology. There are approximately ten times as many Bacterial cells in the human flora as there are human cells in the body, with large numbers of Bacteria on the skin and as gut flora. The vast majority of the Bacteria in the body are rendered harmless by the protective effects of the immune system, and a few are beneficial. However, a few species of Bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy and bubonic plague. The most common fatal Bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people a year, mostly in sub-Saharan Africa. In developed countries, antibiotics are used to treat Bacterial infections and in agriculture, so antibiotic resistance is becoming common.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
Bacteria are vital in recycling nutrients, with many steps in nutrient cycles depending on these organisms, such as the fixation of nitrogen from the atmosphere and putrefaction. However, most Bacteria have not been characterised, and only about half of the phyla of Bacteria have species that can be grown in the laboratory. The study of Bacteria is known as bacteriology, a branch of microbiology. There are approximately ten times as many Bacterial cells in the human flora as there are human cells in the body, with large numbers of Bacteria on the skin and as gut flora. The vast majority of the Bacteria in the body are rendered harmless by the protective effects of the immune system, and a few are beneficial. However, a few species of Bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy and bubonic plague. The most common fatal Bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people a year, mostly in sub-Saharan Africa. In developed countries, antibiotics are used to treat Bacterial infections and in agriculture, so antibiotic resistance is becoming common. In industry, Bacteria are important in sewage ________________________ WORLD TECHNOLOGIES ________________________ treatment, the production of cheese and yogurt through fermentation, as well as in biotechnology, and the manufacture of antibiotics and other chemicals. Once regarded as plants constituting the Class Schizomycetes, Bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, Bacterial cells do not contain a nucleus and rarely harbour membrane-bound organelles. Although the term Bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two very different groups of organisms that evolved independently from an ancient common ancestor. These evolutionary domains are called Bacteria and Archaea.
- David M. Carlberg(Author)
- 2004(Publication Date)
- CRC Press(Publisher)
1 1 THE SCOPE OF MICROBIOLOGY I. INTRODUCTION Microbiology is the branch of biology that deals with the smallest living things, microorganisms. These organisms include Bacteria, algae, fungi, and protozoa. Viruses, while not living organisms in a strict sense, are also included in the study of microorganisms, as are subviral infectious particles such as viroids and prions. Microorganisms are universal. They nearly always occur wherever other forms of life are present, but they also thrive in places where environmental conditions are too harsh for other life. Microorganisms are frequently the only living things found at the bottoms of oil wells, for example, or in the hot springs of Yellowstone National Park, ice-covered lakes in Antarctica, and the extremely dry desert soils of Asia and South America. Bacteria that grow in environments at temperatures higher than the boiling point of water have been isolated near volcanic vents deep in the Pacific Ocean. Natural microbial populations can reach unbelievable levels. Common garden soil is particularly rich in microorganisms. A cubic centimeter (about 1/5 tsp.) may contain as many as 10 9 Bacteria, possibly consisting of up to 7000 different species, most of which have not been named. This mass represents 0.3% of the total bulk of the soil. Stated another way, an acre of soil down to a depth of 3 ft contains about 3000 lb of Bacteria. Scientists have estimated that Bacteria make up about half of all the living biological mass on Earth. The bodies of all animals, including humans, are also rich sources of microorganisms. As many as a million Bacteria may live on each square centimeter of our skin, and saliva may contain 10 9 microorganisms per milliliter. Nasal washings from normal, healthy adults have been shown 2 Cleanroom Microbiology for the Non-Microbiologist to yield as many as 10 5 microorganisms per milliliter. Fecal matter contains about 10 11 Bacteria per gram, which represents about half its dry weight.
eBook - PDF- D. Roy Cullimore(Author)
- 2010(Publication Date)
- CRC Press(Publisher)
Bacteria also require suitable forms of organic forms of carbon. All life as we recognize it also needs other essential elements as macronutrients and micro-nutrients. Above all, water, usually in liquid form, is a universal need and water requires physical and chemical conditions that allow it to an extent to retain its func-tionality as a liquid rather than as a solid (ice) or gas (steam). Bacteria Are Everywhere 27 Various forms of Bacterial biomass have evolved to function high in the atmo-sphere, deep down in the hydrosphere, and within the Earth’s crust. As surface dwell-ers, humans have become preoccupied with the surface biosphere that extends over the 30% of the Earth’s surface area (designated terrestrial). This biosphere contains a vast variety of plants and animals that generally inhabit specific environments. A unique feature of these plants and animals is their ability to remain in one place and grow to obvious size and form (most plants) or move around to feed on other living organisms (animals). The oceans form another major surface-related environment for plants and animals. The plants tend to aggregate near water surfaces where solar energy permeates down from the sun in a diurnal manner (photic zone). Animals tend to find environmental niches throughout the ocean if they have significant levels of oxygen for respiratory functions. The position of this atlas regarding the differentiation of prokaryotic Bacteria is to concentrate on the most primitive of living organisms on the planet. All other organ-isms capable of self-reproduction are defined as eukaryotic and their cells contain many more structures than Bacteria. For this reason, Bacteria are considered one of the first groups of microorganisms subjected to the forces of evolution on earth and they are thus designated alpha group in recognition of the fact that they underwent the earliest durable development of any living organisms.
eBook - PDF- Khushboo Chaudhary, Pankaj Kumar Saraswat(Authors)
- 2023(Publication Date)
- Delve Publishing(Publisher)
Introduction Microorganisms are used routinely in engineered waste treatment systems such as sewage treatment plants. They are also of critical importance in the recovery process of natural environments degraded by human activities, such as in the self-purification of streams receiving sewage and runoff, and the natural attenuation of industrial contaminants leaked or spilled onto the soil. On the other hand, microorganisms have the potential to create substantial environmental problems. For example, they may deplete oxygen, generate Agricultural Microbiology 23 unpleasant tastes and odors, clog equipment, and corrode pipes (Abbott and Murphy, 2003). On this day, we consider the prokaryotic groups, Bacteria and archaea. We also examine the eukaryotic groups containing single-celled organisms: protozoans, algae, fungi and slime molds, even though they also include many multicellular, macroscopic species. There is a wide range of diversity within the world of microorganisms in terms of survival strategy: where they find energy, how they grow, and what environments they prefer. Energy Sources The two major sources of energy are chemical oxidation and photosynthesis. Carbon Sources Since it is a major constituent of cell materials, all organisms need a source of carbon. Heterotrophs (including fungi, protozoans, and most Bacteria) require organic carbon, whereas autotrophs (algae and some Bacteria) consume inorganic carbon (carbon dioxide and bicarbonate). Microbial cells are also commonly classified on the basis of environments they prefer. Several factors are generally considered, including the presence of oxygen, temperature, salt toler- ance, and pH. Strict aerobes require oxygen; cells able to grow at very low oxygen levels may be referred to as microaerophilic. Facultative anaerobes can grow with or without oxygen.
eBook - PDF- Julianne Zedalis, John Eggebrecht(Authors)
- 2018(Publication Date)
- Openstax(Publisher)
A very dangerous strain, methicillin-resistant Staphylococcus aureus (MRSA), has wreaked havoc recently. Foodborne diseases result from the consumption of contaminated food, pathogenic Bacteria, viruses, or parasites that contaminate food. Chapter 22 | Prokaryotes: Bacteria and Archaea 925 22.5 Beneficial Prokaryotes Pathogens are only a small percentage of all prokaryotes. In fact, our life would not be possible without prokaryotes. Nitrogen is usually the most limiting element in terrestrial ecosystems; atmospheric nitrogen, the largest pool of available nitrogen, is unavailable to eukaryotes. Nitrogen can be “fixed,” or converted into ammonia (NH 3 ) either biologically or abiotically. Biological nitrogen fixation (BNF) is exclusively carried out by prokaryotes. After photosynthesis, BNF is the second most important biological process on Earth. The most important source of BNF is the symbiotic interaction between soil Bacteria and legume plants. Microbial bioremediation is the use of microbial metabolism to remove pollutants. Bioremediation has been used to remove agricultural chemicals that leach from soil into groundwater and the subsurface. Toxic metals and oxides, such as selenium and arsenic compounds, can also be removed by bioremediation. Probably one of the most useful and interesting examples of the use of prokaryotes for bioremediation purposes is the cleanup of oil spills. Human life is only possible due to the action of microbes, both those in the environment and those species that call us home. Internally, they help us digest our food, produce crucial nutrients for us, protect us from pathogenic microbes, and help train our immune systems to function correctly. REVIEW QUESTIONS 1. Which is the best evidence that prokaryotes evolved about 3 billion years ago? a. Scientists believe photosynthesis evolved about 3.0 billion years ago. b. There is fossil evidence of mammalian forms going back about 4.0 billion years.
eBook - PDF- Mary Ann Clark, Jung Choi, Matthew Douglas(Authors)
- 2018(Publication Date)
- Openstax(Publisher)
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. In addition to inhabiting moderate environments, they are found in extreme conditions: from boiling springs to permanently frozen environments in Antarctica; from salty environments like the Dead Sea to environments under tremendous pressure, such as the depths of the ocean; and from areas without oxygen, such as a waste management plant, to radioactively contaminated regions, such as Chernobyl. Prokaryotes reside in the human digestive system and on the skin, are responsible for certain illnesses, and serve an important role in the preparation of many foods. 22.1 | Prokaryotic Diversity By the end of this section, you will be able to do the following: • Describe the evolutionary history of prokaryotes • Discuss the distinguishing features of extremophiles • Explain why it is difficult to culture prokaryotes Prokaryotes are ubiquitous. They cover every imaginable surface where there is sufficient moisture, and they also live on and inside virtually all other living things. In the typical human body, prokaryotic cells outnumber human body cells by about ten to one. They comprise the majority of living things in all ecosystems. Some prokaryotes thrive in environments that are inhospitable for most living things. Prokaryotes recycle nutrients—essential substances (such as carbon and nitrogen)—and they drive the evolution of new ecosystems, some of which are natural and others man-made. Prokaryotes have been on Earth since long before multicellular life appeared. Indeed, eukaryotic cells are thought to be the descendants of ancient prokaryotic communities.
eBook - PDFMicrobiology
Principles and Explorations
- Jacquelyn G. Black, Laura J. Black(Authors)
- 2018(Publication Date)
- Wiley(Publisher)
(Bernard LA-SCOLA) © John Wiley and Sons, Inc. 242 CHAPTER 10 An Introduction to Taxonomy: The Bacteria FIGURE 10.14 The three-domain system of classification. Shown here are selected members of the 3 domains. Lengths of the branches indicate the extent of genetic differences in each organism, based on the similarities of their ribosomal RNA. (Source: Adapted from Dr. Carl Woese and Dr. Norman R. Pace, New York Times, April 14, 1998, p. C1.) Animals Fungi Plants Paramecium Porphyra Dictyostelium Entamoeba Naegleria Euglena Trypanosoma Physarum Encephalitozoon Valrimorpha Giardia Hexamita Trichomonas Chromatium Riftia E. coli Mitochondria Agro- bacterium Chlorobium Cytophaga Epulopiscium Bacillus Chloroplast Synechococcus Thermus Thermomicrobium Thermotoga Aquifex EM 17 Methanopyros Marine group 1 Thermococcus Methanococcus Methanobacterium Haloferax Methano- spirillum Methano- sarcina Sulfolobus Thermoproteus Thermofilum pSL 50 pSL 4 pSL 22 pSL 12 pJP 78 pJP 27 ORGANISMS VISIBLE TO HUMAN EYE E B A ? DOMAIN EUKARYA The Eukarya, meaning cells with a nucleus, include all plants and animals, including people. DOMAIN Bacteria Bacteria are single-celled organisms with no nucleus. DOMAIN ARCHAEA The Archaea look like Bacteria but have different genes for managing and reading out their DNA. © John Wiley and Sons, Inc. The Three-Domain Classification System 243 The Archaea The Archaea exhibit many differences from the Bacteria. One of the first variations to be noted was that of cell wall structure, and thus far a significant number of variations have been observed (see Table 10.3). However, not all Archaea are the same. Three major groups are commonly recognized: methanogens, extreme halophiles, and extreme thermophiles. These groupings are based on physiological characteristics of the organisms and therefore cannot be considered phy- logenetic, or evolutionary, classifications.
eBook - PDF- Dave Wessner, Christine Dupont, Trevor Charles, Josh Neufeld(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
Today, the classification of Bacteria relies primarily on DNA sequence analysis. This shift follows from the initial breakthroughs in molecular phylogenetics made by Carl Woese that offered a more natu- ral view of how microorganisms are related to each other. In addition to sequence information from cultured organisms, we also have an increasing amount of sequence data from organisms that have not yet been cultured. These data have affected classification tremendously, in many cases helping to resolve ambiguous relationships by comparing the sequences of shared genes, greatly improving the reliability of identifica- tion methods. Phylogeny of Bacteria As we noted in the previous section, Bacteria can be orga- nized into several major groups, called phyla (singular “phy- lum”). Shown in Figure 2.36 are the major phyla of cultured Bacteria, along with some examples of the better‐known gen- era within each phylum. Note that the majority of Bacteria are not shown in this illustration. Many Bacteria are known only through the detection of their DNA sequences from the environment; we know very little about what they do and the extent of their diversity. Throughout this book, we will intro- duce you to specific Bacteria, providing you with important details and discussing them within the context of specific top- ics. Here, we provide a snapshot of Bacterial diversity by pro- filing a few selected phyla. ProteoBacteria Probably best known for its most famous member, Escherichia coli , the phylum Proteobac- teria includes a wide range of Gram‐negative Bacteria dis- playing an enormous diversity of metabolic and nutritional strategies. Members of this phylum include several human pathogens such as Helicobacter pylori, Vibrio cholerae, and Neisseria gonorrhoeae. Also within this phylum are nitro- gen‐fixing soil Bacteria in the genus Rhizobium and the important plant pathogen Agrobacterium tumefaciens.
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