Bacteria in this genus are widely used as model organisms in microbial research, and include a range of important species in fields such as plant pathogenicity, bioremediation, and environmental microbiology. As well as being hugely important in the medical and pharmaceutical industries, Streptomyces also play a significant environmental role; contributing to the decomposition of organic matter, and fertility of the soil.
Microbiology Today : Mycobacteria. Science Photo Library. Building bacterial bridges. Tuberculosis Explainer. Antimicrobial resistance. Pseudomonas - friend and foe. Homepage Why Microbiology Matters What is microbiology?
Bacteria Bacteria are single celled microbes. Survival mechanism Some bacteria can form endospores. Observing bacteria in a Petri dish Educational resource for students: Observing bacteria cultures in a Petri dish and learning about colony morphology. Microbiology Today: Mycobacteria The organisms that cause tuberculosis in humans and animals, Mycobacterium tuberculosis and Mycobacterium bovis , are featured in this edition of Microbiology Today alongside Mycobacterium leprae , the cause of leprosy, and Mycobacterium ulcerans , which causes Buruli ulcer.
Building bacterial bridges Often, the first things that come to mind when we think about microbes in the built environment are damage, decay, discolouration and staining to building materials and their surfaces. Tuberculosis explainer Tuberculosis TB is a debilitating multi-organ disease caused by the bacterium Mycobacterium tuberculosis.
Antimicrobial resistance AMR The threat of antimicrobial resistance AMR has now been recognised globally and it is estimated that 10 million people a year will die due to antimicrobial resistance by if no urgent action is taken.
Pseudomonas - friend and foe Species within the genus Pseudomonas are amongst the most researched bacteria in the scientific community.
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Meet the people trying to help. Animals Whales eat three times more than previously thought. Environment Planet Possible India bets its energy future on solar—in ways both small and big. Bacteria are prokaryotes, lacking well-defined nuclei and membrane-bound organelles, and with chromosomes composed of a single closed DNA circle.
They come in many shapes and sizes, from minute spheres, cylinders and spiral threads, to flagellated rods, and filamentous chains. They are found practically everywhere on Earth and live in some of the most unusual and seemingly inhospitable places. Evidence shows that bacteria were in existence as long as 3. Even older than the bacteria are the archeans also called archaebacteria tiny prokaryotic organisms that live only in extreme environments: boiling water, super-salty pools, sulfur-spewing volcanic vents, acidic water, and deep in the Antarctic ice.
Many scientists now believe that the archaea and bacteria developed separately from a common ancestor nearly four billion years ago. Millions of years later, the ancestors of today's eukaryotes split off from the archaea. Despite the superficial resemblance to bacteria, biochemically and genetically, the archea are as different from bacteria as bacteria are from humans.
In the late s, Antoni van Leeuwenhoek became the first to study bacteria under the microscope. During the nineteenth century, the French scientist Louis Pasteur and the German physician Robert Koch demonstrated the role of bacteria as pathogens causing disease.
The twentieth century saw numerous advances in bacteriology, indicating their diversity, ancient lineage, and general importance. Most notably, a number of scientists around the world made contributions to the field of microbial ecology, showing that bacteria were essential to food webs and for the overall health of the Earth's ecosystems.
The discovery that some bacteria produced compounds lethal to other bacteria led to the development of antibiotics, which revolutionized the field of medicine. There are two different ways of grouping bacteria. They can be divided into three types based on their response to gaseous oxygen. Aerobic bacteria require oxygen for their health and existence and will die without it. Anerobic bacteria can't tolerate gaseous oxygen at all and die when exposed to it.
Facultative aneraobes prefer oxygen, but can live without it. The second way of grouping them is by how they obtain their energy. Bacteria that have to consume and break down complex organic compounds are heterotrophs. This includes species that are found in decaying material as well as those that utilize fermentation or respiration.
Bacteria that create their own energy, fueled by light or through chemical reactions, are autotrophs. Capsule - Some species of bacteria have a third protective covering, a capsule made up of polysaccharides complex carbohydrates.
Capsules play a number of roles, but the most important are to keep the bacterium from drying out and to protect it from phagocytosis engulfing by larger microorganisms. The capsule is a major virulence factor in the major disease-causing bacteria, such as Escherichia coli and Streptococcus pneumoniae. Nonencapsulated mutants of these organisms are avirulent, i. Cell Envelope - The cell envelope is made up of two to three layers: the interior cytoplasmic membrane, the cell wall, and -- in some species of bacteria -- an outer capsule.
Cell Wall - Each bacterium is enclosed by a rigid cell wall composed of peptidoglycan, a protein-sugar polysaccharide molecule. The wall gives the cell its shape and surrounds the cytoplasmic membrane, protecting it from the environment.
It also helps to anchor appendages like the pili and flagella, which originate in the cytoplasm membrane and protrude through the wall to the outside. The strength of the wall is responsible for keeping the cell from bursting when there are large differences in osmotic pressure between the cytoplasm and the environment.
Cell wall composition varies widely amongst bacteria and is one of the most important factors in bacterial species analysis and differentiation. For example, a relatively thick, meshlike structure that makes it possible to distinguish two basic types of bacteria.
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