Is the most resistant form of bacterial life?
While more R&D is vital, alone, it cannot solve the problem. To address resistance, there must also be better prevention of infections and appropriate use of existing antibiotics in humans and animals, as well as rational use of any new antibiotics that are developed in future.
Bacteria are microscopic, single-celled organisms that exist in their millions, in every environment, both inside and outside other organisms. Show
Some bacteria are harmful, but most serve a useful purpose. They support many forms of life, both plant and animal, and they are used in industrial and medicinal processes. Bacteria are thought to have been the first organisms to appear on earth, about 4 billion years ago. The oldest known fossils are of bacteria-like organisms. Bacteria can use most organic and some inorganic compounds as food, and some can survive extreme conditions. A growing interest in the function of the gut microbiome is shedding new light on the roles bacteria play in human health. What are bacteria?Share on PinterestBacteria are single-celled organisms. Bacteria are single-cell organisms that are neither plants nor animals. They usually measure a few micrometers in length and exist together in communities of millions. A gram of soil typically contains about 40 million bacterial cells. A milliliter of fresh water usually holds about one million bacterial cells. The earth is estimated to hold at least 5 nonillion bacteria, and much of the earth’s biomass is thought to be made up of bacteria. Types There are many different types of bacteria. One way of classifying them is by shape. There are three basic shapes.
There are many variations within each shape group. Structure Bacterial cells are different from plant and animal cells. Bacteria are prokaryotes, which means they have . A bacterial cell includes:
Feeding Bacteria feed in different ways. Heterotrophic bacteria, or heterotrophs, get their energy through consuming organic carbon. Most absorb dead organic material, such as decomposing flesh. Some of these parasitic bacteria kill their host, while others help them. Autotrophic bacteria (or just autotrophs) make their own food, either through either:
Bacteria that use photosynthesis are called photoautotrophs. Some types, for example cyanobacteria, produce oxygen. These probably played a vital role in creating the oxygen in the earth’s atmosphere. Others, such as heliobacteria, do not produce oxygen. Those that use chemosynthesis are known as chemoautotrophs. These bacteria are commonly found in ocean vents and in the roots of legumes, such as alfalfa, clover, peas, beans, lentils, and peanuts. Where do they live?Share on PinterestBacteria can thrive even in extreme environments, such as glaciers. Bacteria can be found in soil, water, plants, animals, radioactive waste, deep in the earth’s crust, arctic ice and glaciers, and hot springs. There are bacteria in the stratosphere, between 6 and 30 miles up in the atmosphere, and in the ocean depths, down to 32,800 feet or 10,000 meters deep. Aerobes, or aerobic bacteria, can only grow where there is oxygen. Some types can cause problems for the human environment, such as corrosion, fouling, problems with water clarity, and bad smells. Anaerobes, or anaerobic bacteria, can only grow where there is no oxygen. In humans, this is mostly in the gastrointestinal tract. They can also cause gas, gangrene, tetanus, botulism, and most dental infections. Facultative anaerobes, or facultative anaerobic bacteria, can live either with or without oxygen, but they prefer environments where there is oxygen. They are mostly found in soil, water, vegetation and some normal flora of humans and animals. Examples include Salmonella. Mesophiles, or mesophilic bacteria, are the bacteria responsible for most human infections. They thrive in moderate temperatures, around 37°C. This is the temperature of the human body. Examples include Listeria monocytogenes, Pesudomonas maltophilia, Thiobacillus novellus, Staphylococcus aureus, Streptococcus pyrogenes, Streptococcus pneumoniae, Escherichia coli, and Clostridium kluyveri. The human intestinal flora, or gut microbiome, contains beneficial mesophilic bacteria, such as dietary Lactobacillus acidophilus. Extremophiles, or extremophilic bacteria, can withstand conditions considered too extreme for most life forms. Thermophiles can live in high temperatures, up to 75 to 80°C, and hyperthermophiles can surivive in temperatures up to 113°C. Deep in the ocean, bacteria live in total darkness by thermal vents, where both temperature and pressure are high. They make their own food by oxidizing sulfur that comes from deep inside the earth. Other extremophiles include:
Extremophiles can survive where no other organism can. Reproduction and transformationBacteria may reproduce and change using the following methods:
Some bacteria produce endospores, or internal spores, while others produce exospores, which are released outside. These are known as cysts. Clostridium is an example of an endospore-forming bacterium. There are about 100 species of Clostridium, including Clostridium botulinim (C. botulinim) or botulism, responsible for a potentially fatal kind of food poisoning, and Clostridium difficile (C. Difficile), which causes colitis and other intestinal problems. Uses Bacteria are often thought of as bad, but many are helpful. We would not exist without them. The oxygen we breathe was probably created by the activity of bacteria. Human survivalMany of the bacteria in the body play an important role in human survival. Bacteria in the digestive system break down nutrients, such as complex sugars, into forms the body can use. Non-hazardous bacteria also help prevent diseases by occupying places that the pathogenic, or disease-causing, bacteria want to attach to. Some bacteria protect us from disease by attacking the pathogens. Nitrogen fixationBacteria take in nitrogen and release it for plant use when they die. Plants need nitrogen in the soil to live, but they cannot do this themselves. To ensure this, many plant seeds have a small container of bacteria that is used when the plant sprouts. Food technologyShare on PinterestCheesemaking involves bacteria. Lactic acid bacteria, such as Lactobacillus and Lactococcus together with yeast and molds, or fungi, are used to prepare foods such as as cheese, soy sauce, natto (fermented soy beans), vinegar, yogurt, and pickles. Not only is fermentation useful for preserving foods, but some of these foods may offer health benefits. For example, some fermented foods contain types of bacteria that are similar to those linked with gastrointestinal health. Some fermentation processes lead to new compounds, such as lactic acid, which that appear to have an anti-inflammatory effect. More investigation is needed to confirm the health benefits of fermented foods. Bacteria in industry and researchBacteria can break down organic compounds. This is useful for activities such as waste processing and cleaning up oil spills and toxic waste. The pharmaceutical and chemical industries use bacteria in the production of certain chemicals. Bacteria are used in molecular biology, biochemistry and genetic research, because they can grow quickly and are relatively easy to manipulate. Scientists use bacteria to study how genes and enzymes work. Bacteria are needed to make antibiotics. Bacillus thuringiensis (Bt) is a bacterium that can be used in agriculture instead of pesticides. It does not have the undesirable environmental consequences associated with pesticide use. Hazards Some types of bacteria can cause diseases in humans, such as cholera, diptheria, dysentery, bubonic plague, pneumonia, tuberculosis (TB), typhoid, and many more. If the human body is exposed to bacteria that the body does not recognize as helpful, the immune system will attack them. This reaction can lead to the symptoms of swelling and inflammation that we see, for example, in an infected wound. Resistance In 1900, pneumonia, TB, and diarrhea were the three biggest killers in the United States. Sterilization techniques and antibiotic medications have led to a significant drop in deaths from bacterial diseases. However, the overuse of antibiotics is making bacterial infection harder to treat. As the bacteria mutate, they become more resistant to existing antibiotics, making infections harder to treat. Bacteria transform naturally, but the overuse of antibiotics is speeding up this process.
For this reason, scientists and health authorities are calling on doctors not to prescribe antibiotics unless it is necessary, and for people to practice other ways of preventing disease, such as good food hygiene, hand washing, vaccination, and using condoms. The gut microbiomeRecent research has led to a new and growing awaress of how the human body interacts with bacteria, and particularly the communities of bacteria living in the intestinal tract, known as the gut microbiome, or gut flora. In 2009, researchers publishedfindingssuggesting that women with obesity were more likely to have a particular kind of bacteria, Selenomonas noxia (S. noxia), in their mouth. In 2015, scientists at the University of North Carolina found that the intestines of people with anorexia contain “very different” bacteria, or microbial commiunities, compared with people who do not have the condition. They suggest that this may have a psychological impact. History Over 2,000 years ago, a Roman author, Marcus Terentius Varro, suggested that disease may be caused by tiny animals that floated in the air. He advised people to avoid marshy places during building work because they might contain insects too small for the eye to see that entered the body through the mouth and nostrils and cause diseases. In the 17th century, a Dutch scientist, Antonie van Leeuwenhoek created a single-lens microscope with which he saw what he called animalcules, later known as bacteria. He is considered to be the first microbiologist. In the 19th century, the chemists Louis Pasteur and Robert Koch said that diseases were caused by germs. This was known as the Germ Theory. In the 1910, the scientist Paul Ehrlich announed the development of the first antibiotic, Salvarsan. He used it to cure syphilis. He was also the first scientist to detect bacteria by using stains. In 2001, Joshua Lederburg coined the term “gut microbiome,” and scientists worldwide are currentlyseeking to describeand understand more precisely the structures, types, and uses of “gut flora,” or bacteria in the human body. What are the most resistant microbial forms?Except for prions, bacterial spores possess the highest innate resistance to chemical germicides, followed by coccidia (e.g., Cryptosporidium), mycobacteria (e.g., M.
Which form of a bacterial cell is more resistant to heat?Ascospores are usually extremely resistant to heat, with DT values that can reach those of bacterial spores [4].
What are the most resistant infectious particles?Prions are also unique in that they do not contain nucleic acid, unlike bacteria, fungi, viruses, and other pathogens. Prions are therefore resistant to procedures that destroy pathogens by breaking down nucleic acid.
Why are bacterial spores highly resistant?These resistance factors include the outer layers of the spore, such as the thick proteinaceous coat that detoxifies reactive chemicals; the relatively impermeable inner spore membrane that restricts access of toxic chemicals to the spore core containing the spore's DNA and most enzymes; the low water content and high ...
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