Which term describes an organism that adheres to multiple species to facilitate colonization?

• A. Pioneer species
• B. Keystone species
• C. Helper species
• D. Bridging species

Answer: (D)

The idea being tested is how some organisms act as links between different members of a microbial community by attaching to more than one species, thereby aiding colonization and biofilm maturation. An organism that can adhere to multiple different bacteria serves as a bridge, connecting early colonizers with later-arriving species and helping the community establish more quickly. A classic example in the mouth is Fusobacterium nucleatum, which can bind to early colonizers like Streptococcus species and to later colonizers, facilitating the progression of the biofilm. This bridging role is what makes the term bridging species the best fit for describing an organism that adheres to multiple species to promote colonization.

Pioneer species describe microbes that first attach to a surface, initiating biofilm formation, but they don’t inherently link to multiple other species. Keystone species refer to organisms with a disproportionate influence on the ecosystem’s structure and function, not specifically about adhesion to various partners. Helper species isn’t a standard term used to describe this bridging function.