What term describes the partnership between a host and resident microflora?

The term that best describes the partnership between a host and its resident microflora is symbiosis. Symbiosis encompasses a broad range of interactions between two different organisms, which can include mutualism, commensalism, and parasitism.

In the context of resident microflora, many of these microorganisms engage in mutually beneficial relationships with their host (mutualism), where both parties gain from the association, such as the gut bacteria that help digestion while receiving nutrients in return. However, symbiosis is the overarching term that encapsulates various types of interactions, including those that might not be strictly mutualistic.

While other terms like mutualism, commensalism, and parasitism describe specific relationships within symbiosis, they do not capture the full spectrum of interactions. Mutualism highlights a beneficial reciprocal relationship, commensalism refers to one organism benefiting while the other remains unaffected, and parasitism involves one organism benefiting at the expense of the other. Therefore, symbiosis is the most comprehensive and appropriate term to describe the partnership between a host and its resident microflora.