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Transmission can also be indirect, via another organism, either a vector (e.g. a mosquito or fly) or an intermediate host (e.g. tapeworm in pigs can be transmitted to humans who ingest improperly cooked pork). Indirect transmission could involve zoonoses or, more typically, larger pathogens like macroparasites with more complex life cycles.
Bacterial motility is the ability of bacteria to move independently using metabolic energy. Most motility mechanisms that evolved among bacteria also evolved in parallel among the archaea . Most rod-shaped bacteria can move using their own power, which allows colonization of new environments and discovery of new resources for survival.
As microorganisms, in particular bacteria, are found virtually everywhere, harmful microorganisms may be reduced to acceptable levels rather than actually eliminated. In food preparation, microorganisms are reduced by preservation methods such as cooking, cleanliness of utensils, short storage periods, or by low temperatures.
A representation by Robert Seymour of the cholera epidemic depicts the spread of the disease in the form of poisonous air.. The miasma theory was the predominant theory of disease transmission before the germ theory took hold towards the end of the 19th century; it is no longer accepted as a correct explanation for disease by the scientific community.
Horizontal transmission is the transmission of organisms between biotic and/or abiotic members of an ecosystem that are not in a parent-progeny relationship. Because the evolutionary fate of the agent is not tied to reproductive success of the host, horizontal transmission tends to evolve virulence .
The ability of each microorganism to degrade toxic waste depends on the nature of each contaminant. Since sites typically have multiple pollutant types, the most effective approach to microbial biodegradation is to use a mixture of bacterial and fungal species and strains, each specific to the biodegradation of one or more types of contaminants.
Bacteria in the culture on the right are resistant to most of the antibiotics. In addition to drugs being specific to a certain kind of organism (bacteria, fungi, etc.), some drugs are specific to a certain genus or species of organism, and will not work on other organisms. Because of this specificity, medical microbiologists must consider the ...
Exogenous bacteria are microorganisms introduced to closed biological systems from the external world. [citation needed] They exist in aquatic and terrestrial environments, as well as the atmosphere. Microorganisms in the external environment have existed on Earth for 3.5 billion years. [1] Exogenous bacteria can be either benign or pathogenic.