Biofilms are aggregates of bacteria that adhere to surfaces and display increased resistance to antibiotics. Two main healthcare concerns are the disinfection of surgical surfaces and equipment and the treatment of infections in humans. Individuals infected with biofilm-forming bacteria present recurring infections and require severe drug treatment. Commensal Neisseria species are found in human oral and nasopharynx. These commensal species are closely related to the pathogenic N. gonorrhoeae which is known to form biofilms. Here, we characterize biofilm formation by commensal Neisseria species, N. cinerea, N. mucosa, and N. elongata. I predict that N. cinerea will have the highest level of biofilm formation. We performed a standard multiwell static model biofilm assay and measured the accumulation of crystal violet by the biofilm. Overall, all commensals studied formed less biofilm than N. gonorrhoeae, and in particular, N. cinerea formed 3.2 times less biofilm than N. mucosa and 2.7 times less than N. elongata. These results were unexpected given the great genomic similarity between all Neisseria genus species. Hence, while Neisseria seem able to form biofilms, there is a wide range of their ability to form these structures. We will analyze the potential genetic differences that explain this variation.
