Search results
Results from the WOW.Com Content Network
Bacteria and archaea are almost always microscopic, while a number of eukaryotes are also microscopic, including most protists, some fungi, as well as some micro-animals and plants. Viruses are generally regarded as not living and therefore not considered to be microorganisms, although a subfield of microbiology is virology , the study of viruses.
It states that microorganisms known as pathogens or "germs" can cause disease. These small organisms, which are too small to be seen without magnification, invade animals, plants, and even bacteria. Their growth and reproduction within their hosts can cause disease.
Plants can play host to a wide range of pathogen types, including viruses, bacteria, fungi, nematodes, and even other plants. [35] Notable plant viruses include the papaya ringspot virus , which has caused millions of dollars of damage to farmers in Hawaii and Southeast Asia, [ 36 ] and the tobacco mosaic virus which caused scientist Martinus ...
Virulence is a pathogen's or microorganism's ability to cause damage to a host. In most cases, especially in animal systems, virulence refers to the degree of damage caused by a microbe to its host. [1] The pathogenicity of an organism—its ability to cause disease—is determined by its virulence factors.
Pathogenic bacteria are bacteria that can cause disease. [1] This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and many are beneficial but others can cause infectious diseases .
Most bacteria associated with plants are saprotrophic and do no harm to the plant itself. However, a small number, around 100 known species, cause disease, especially in subtropical and tropical regions of the world. [15] [page needed] Most plant pathogenic bacteria are bacilli. Erwinia uses cell wall–degrading enzymes to cause soft rot.
They infect all types of cellular life including animals, plants, bacteria and fungi. [6]: 49 Different types of viruses can infect only a limited range of hosts and many are species-specific. Some, such as smallpox virus for example, can infect only one species—in this case humans, [13]: 643 and are said to have a narrow host range. Other ...
A pathogenic cause for a known medical disease may only be discovered many years later, as was the case with Helicobacter pylori and peptic ulcer disease. [224] Bacterial diseases are also important in agriculture, and bacteria cause leaf spot, fire blight and wilts in plants, as well as Johne's disease, mastitis, salmonella and anthrax in farm ...