They can be spheres, they can be rods, or they can be spirals. There are bacteria that are bad, that we call pathogenic, and they will cause diseases, but there's also good bacteria. As an example, in our digestive system, in the gut, we have bacteria that are very necessary to help our bodies function in a normal way. What's interesting about bacteria is that in our bodies we have 10 times more bacterial cells than we have human cells.
Bacteria are also important in biotechnology. They are also important in that they, again, will help the body maintain itself in a healthy manner. Zero sunlight reaches it. Its temperatures are frigid. Little surprise, then, that most of the locals are microscopic. They have adapted its extreme conditions. Biddle and other scientists teamed up with deep-ocean explorers to send a submarine to Challenger Deep. James Cameron piloted the vessel.
The vessel also brought back sediment from the bottom of the trench. Biddle and the other scientists screened that sediment for DNA.
They were scouting for genes of familiar bacteria. They turned up evidence of some known as Parcubacteria. Back then, they found some in groundwater and dirt from a few places on land.
Here, on the trench floor, the microbes were breathing nitrogen, not oxygen as they did on land. And that makes sense. They had adapted to nitrogen since their home had little access to oxygen. The more places we find such little-known bacteria, says Biddle, the more we can learn about what they do for their ecosystems. Sourdough bread gets its unique tart flavor when a mix of bacteria munches on the sugars in bread flour.
Those bacteria make carbon dioxide, acids and other flavorful compounds. But to function, sourdough bacteria need their friends. No sourdough. And he suspected he could use the lessons of sourdough to make better biofuels. These plant-based fuels can power cars or trucks. To make biofuels, scientists must break down plants into sugars. These sugars can then be turned into fuels such as ethanol a type of alcohol. The chemical reactions that break down the plants require help from enzymes.
These are molecules that jump-start or speed up chemical reactions. The enzymes currently used to make biofuels are expensive. He turned his search for them to the compost pile. There, bacterial communities were hard at work breaking down rotting fruits and veggies. Singer took a small sample of the compost back to his lab. There, he let bacteria from the compost grow in a beaker.
Later, he collected enzymes that these bacteria made and tested them on other plant bits. It worked: The enzymes broke down the plants into sugars. Just as the sourdough bacteria need their friends to function, Singer discovered that these microbes produced the useful enzymes only when they were part of robust communities of different compost bacteria.
Singer is now scaling up his project. His team is growing bacteria in huge vats called bioreactors. After he makes lots of the new enzymes, he can test whether they work better than existing ones for converting plant wastes into fuels. Singer is studying his new enzymes without knowing which bacteria are making them. Bacteria are invisible to the unaided eye.
Even with a microscope, telling two species apart can be hard. Key to this sleuthing: DNA. All organisms shed a little DNA throughout their environment. Some of these parasitic bacteria kill their host, while others help them. Bacteria that use photosynthesis are called photoautotrophs.
Some types, for example cyanobacteria, produce oxygen. 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. There are bacteria in the stratosphere, between 6 and 30 miles up in the atmosphere, and in the ocean depths, down to 32, feet or 10, 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. 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. 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.
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 species of Clostridium , including Clostridium botulinim C. Difficile , which causes colitis and other intestinal problems. 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. Many 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. Bacteria 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. 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.
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