commensalism

Examples of commensalism in the following topics:

• Mutualism vs. Symbiosis

  • Symbiosis is a relationship between two organisms: it can be mutualistic (both benefit), commensal (one benefits), or parasitic.
  • Commensalism: In commensalism, one organism benefits while the other organism neither benefits nor suffers from the interaction.

• Overview of Human-Microbial Reactions

  • Human-microbial interactions can be commensal or mutualistic, as with many types of gut flora, or harmful, as with pathogenic bacteria.
  • The relationship between gut flora and humans is thought to be not merely commensal, but rather a mutualistic relationship.
  • Skin flora are usually non-pathogenic and either commensal or mutualistic.

• Host Range

  • A host is an organism that harbors a parasite or a mutual or commensal symbiont, typically providing nourishment and shelter.

• Ecological Associations Among Microorganisms

  • These symbiotic associations can be divided into parasitism, mutualism and commensalism.
  • Due to their small size, commensal bacteria are ubiquitous and grow on animals and plants exactly as they would grow on any other surface.

• Innate Resistance

  • Within the genitourinary and gastrointestinal tracts, commensal flora serve as biological barriers by competing with pathogenic bacteria for food and space and, in some cases, by changing the conditions in their environment, such as pH or available iron.
  • The majority of these commensal bacteria are anaerobes, meaning they survive in an environment with no oxygen.

• Microbiota of the Skin

  • Skin flora are usually non-pathogenic, and either commensals (are not harmful to their host) or mutualistic (offer a benefit).
  • Skin microflora can be commensals, mutualistic, or pathogens.

• Introduction to Plasmids

  • Microbial transformation with plasmid DNA is neither parasitic nor symbiotic in nature, because each implies the presence of an independent species living in a commensal or detrimental state with the host organism.

• Ecology, Epidemiology, and Evolution of Pathogens

  • In most cases, microorganisms live in harmony with their hosts via mutual or commensal interactions.

• Colonization and Growth

  • All multicellular organisms are colonized to some degree by extrinsic organisms and the vast majority of these exist in either a mutualistic or commensal relationship with the host.

• Host Risk Factors

  • C. difficile is a commensal bacterium of the human intestine in 2-5% of the population.