Some bacteria have no cell walls, which makes it difficult to classify their shapes as spherical, rod-shaped or spiral. Mycoplasma bacteria are resistant to many antibiotics due to their lack of cell walls, and are the smallest form of bacterial cells. Now you have seen lots of different examples of bacteria, the types of bacteria and some of the things that bacteria can do. If you're interested in learning more about common bacteria, take a look at these five common eubacteria examples. Or, if you want to prevent some of these bacterial infections, try out these tips on how to kill household germs and bacteria.
From there, explore some more fun facts about bacteria. All rights reserved. Sphere-Shaped Bacteria Coccus bacteria , or cocci, are sphere or oval-shaped bacteria that grow in chains or clusters. Rod-Shaped Bacteria Bacillus is Latin for "stick," which describes the rod-like shape of this type of bacteria. Rod-Shaped Bacteria That Ferment Food While some rod-shaped bacteria can make you very sick, other types can bring your food to the perfect ripeness. Acetobacter aceti converts ethanol to acetic acid and works in sugar fermentation Arthrobacter nicotianae grown with cane or beet molasses Arthrobacter arilaitensis found on the surfaces of smear-ripened cheeses Bifidobacterium adolescentis healthy gut bacteria found in babies Brachybacterium tyrofermentans works in cheese fermentation Brevibacterium linens causes foot odor on human skin; ferments mold-ripened cheeses Carnobacterium divergens found in spoiled meat and dairy products Gluconobacter oxydans causes rot in fruits and vegetables Hafnia alvei used as a probiotic in dairy supplement products Lactobacillus acetotolerans found in rice wine vinegar Lactobacillus acidifarinae used in sourdough bread starters Lactobacillus helveticus used in cheese-making Lactococcus lactis used to make buttermilk and other dairy products Pseudomonas fluorescens causes milk to spoil and coagulate Weissella koreensis found in kimchi Zymomonas mobilis found in wine and beer spoilage.
Rickettsia Examples Bacteria from the genus Rickettsia are primarily rod-shaped, though some can be spherical like cocci. Examples of Rickettsia bacteria include: Rickettsia akari transmitted by mites; causes rickettsialpox Rickettsia conorii transmitted by ticks; causes boutonneuse fever, spotted fever and tick typhus Rickettsia felis transmitted by fleas; causes spotted fever Rickettsia prowazekii transmitted by lice; causes louse-borne typhus Rickettsia rickettsii transmitted by ticks; causes Rocky Mountain spotted fever Rickettsia typhi transmitted by rat fleas; causes typhus.
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. 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 can break down organic compounds. This is useful for activities such as waste processing and cleaning up oil spills and toxic waste. 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. Bacillus thuringiensis Bt is a bacterium that can be used in agriculture instead of pesticides. Delving beneath the cell wall and membrane, bacteria contain cytoplasm, a solution of mostly water and salts.
Within the cytoplasm float the nucleoid, plasmids and tiny protein factories called ribosomes, which are the sites where the cell's genetic instructions are translated into the cell's products. Some antibiotics, like tetracycline, target bacterial ribosomes to prevent them from synthesizing proteins, thus dooming the cell. The cytoplasm of some bacteria may also have little pockets, called inclusions, where nutrients are stored for lean times.
Photosynthetic bacteria, which generate energy from sunlight, may have structures called chromatophores spread throughout their cytoplasm. These chromatophores hold pigments used in photosynthesis. As some of the oldest life-forms on Earth , bacteria have evolved a dizzying number of ways to survive. Some bacteria are photosynthetic, while others are master decomposers, breaking down rotting and decaying organic material into nutrients.
Some enter symbiotic, or mutually beneficial, relationships with a host more on this later. Most bacteria multiply by a process called binary fission , according to the Cornell University College of Agriculture and Life Sciences. In this process, a single bacterial cell, called the "parent," makes a copy of its DNA and grows larger by doubling its cellular content. The cell then splits apart, pushing the duplicated material out and creating two identical "daughter" cells.
Some types of bacteria, such as cyanobacteria and firmicutes, reproduce via budding. In this case, the daughter cell grows as an offshoot of the parent. It starts off as a small nub, grows until it is the same size as its parent and then splits off. After binary fission or budding, the DNA found in parents and offspring is exactly the same.
Therefore, bacterial cells introduce variation into their genetic material by integrating additional DNA, often from their surroundings, into their genome. The resulting genetic variation ensures that bacteria can adapt and survive as their environment changes, Live Science previously reported.
There are three ways horizontal gene transfer occurs: transformation, transduction and conjugation. Transformation is the most common process of horizontal gene transfer and occurs when a bacterium absorbs short DNA fragments from the environment through its cell membrane. The DNA fragments are released into the environment by other bacteria.
To undergo transformation, a bacterium must be in a state known as competence. This usually happens when nutrients are scarce or when the density of a bacterial colony is high. In these circumstances, it might be evolutionarily advantageous to try out some new DNA. Transduction occurs when a virus picks up DNA from one bacterium and infects another bacterium, inserting the new gene sequence. Conjunction happens when bacteria make direct contact.
A donor cell sprouts a tube-like appendage, called a pilus, and directly passes DNA to a recipient cell. This happens with E. Freeman and Company, The third type of transfer, called conjugation, aids in the spread of antibiotic-resistance genes. Many bacteria are beneficial to humans. We harness their power to curdle milk into yogurt and ferment cabbage into kimchi. Some species even do their work inside us. According to the Microbiology Society, there are about 10 times as many bacterial cells as human cells inside a person's body, and many of these live in the digestive tract.
These bacteria get a constant stream of nutrients from the human gut. In return, they help break down foods that human digestive enzymes can't.
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