Intéractions microorganisms-hosts-environment.

Abstract

Within a biocenosis, different types of interactions are observed between individuals of different species (interspecific interactions) or of the same species (intraspecific interactions). Interspecific interactions can be positive (mutualism, commensalism, syntrophism, synergism or protocooperation), neutral (neutralism) or negative (parasitism, amensalism or antagonism, competition, predation).  Positive interactions - Mutualism : an interaction in which both partners benefit from their association, but still can live independently. If the interaction is mandatory, i.e. at least one of the partners involved cannot live without the other, and the organisms are in contact, this is called symbiotic mutualism. - Commensalism : long-term interaction between individuals of different species where one partner benefits from the association while the other finds neither advantage nor real disadvantage. - Syntrophisme : a combination of two microorganisms that cooperate for a specific overall metabolic activity and depend on each other for growth and existence. - Proto-cooperation : interaction between organisms of different species in which both benefit without interaction being mandatory.  Neutral interactions - Neutralism : no interaction between two species living in the same biotope.  Negative interactions - Amensalism : an interaction in which one species excretes a substance that inhibits the development of the other. - Parasitism : An interaction between two organisms, one of which (the parasite) lives at the expense of the other (the host) while harming it. A distinction is made between ectoparasites (living on the surface of their hosts) and endoparasites (living inside their hosts). - Competition : competition between organisms for a resource, food, or for the appropriation of a habitat. - Predation : interaction between organisms where one (predator) feeds on the other (prey).

Intraspecific relationships are established between individuals of the same species, forming a population. These are phenomena of cooperation or competition, with the sharing of territory, and sometimes organization into hierarchical societies.