title: L-arginine destabilizes oral multi-species biofilm communities developed in human saliva.
abstract: The amino acid L-arginine inhibits bacterial coaggregation, is involved in cell-cell signaling, and alters bacterial metabolism in a broad range of species present in the human oral cavity. Given the range of effects of L-arginine on bacteria, we hypothesized that L-arginine might alter multi-species oral biofilm development and cause developed multi-species biofilms to disassemble. Because of these potential biofilm-destabilizing effects, we also hypothesized that L-arginine might enhance the efficacy of antimicrobials that normally cannot rapidly penetrate biofilms. A static microplate biofilm system and a controlled-flow microfluidic system were used to develop multi-species oral biofilms derived from pooled unfiltered cell-containing saliva (CCS) in pooled filter-sterilized cell-free saliva (CFS) at 37° C. The addition of pH neutral L-arginine monohydrochloride (LAHCl) to CFS was found to exert negligible antimicrobial effects but significantly altered biofilm architecture in a concentration-dependent manner. Under controlled flow, the biovolume of biofilms (μm(3)/μm(2)) developed in saliva containing 100-500 mM LAHCl were up to two orders of magnitude less than when developed without LAHCI. Culture-independent community analysis demonstrated that 500 mM LAHCl substantially altered biofilm species composition: the proportion of Streptococcus and Veillonella species increased and the proportion of Gram-negative bacteria such as Neisseria and Aggregatibacter species was reduced. Adding LAHCl to pre-formed biofilms also reduced biovolume, presumably by altering cell-cell interactions and causing cell detachment. Furthermore, supplementing 0.01% cetylpyridinium chloride (CPC), an antimicrobial commonly used for the treatment of dental plaque, with 500 mM LAHCl resulted in greater penetration of CPC into the biofilms and significantly greater killing compared to a non-supplemented 0.01% CPC solution. Collectively, this work demonstrates that LAHCl moderates multi-species oral biofilm development and community composition and enhances the activity of CPC. The incorporation of LAHCl into oral healthcare products may be useful for enhanced biofilm control.
authors.affiliation: Center for Molecular and Clinical Epidemiology of Infectious Diseases, Department of Epidemiology, University of Michigan, Ann Arbor, MI, United States of America.
authors.forename: Ethan
authors.initials: E
authors.lastname: Kolderman
authors.affiliation: Center for Molecular and Clinical Epidemiology of Infectious Diseases, Department of Epidemiology, University of Michigan, Ann Arbor, MI, United States of America.
authors.forename: Deepti
authors.initials: D
authors.lastname: Bettampadi
authors.affiliation: Center for Molecular and Clinical Epidemiology of Infectious Diseases, Department of Epidemiology, University of Michigan, Ann Arbor, MI, United States of America.
authors.forename: Derek
authors.initials: D
authors.lastname: Samarian
authors.affiliation: Molecular Research LP (MR DNA), Shallowater, TX, United States of America.
authors.forename: Scot E
authors.initials: SE
authors.lastname: Dowd
authors.affiliation: Center for Molecular and Clinical Epidemiology of Infectious Diseases, Department of Epidemiology, University of Michigan, Ann Arbor, MI, United States of America.
authors.forename: Betsy
authors.initials: B
authors.lastname: Foxman
authors.affiliation: Centre for Oral Health Research, School of Dental Sciences, Newcastle University, Newcastle upon Tyne, NE2 4BW, United States of America.
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Jakubovics
authors.affiliation: Center for Molecular and Clinical Epidemiology of Infectious Diseases, Department of Epidemiology, University of Michigan, Ann Arbor, MI, United States of America.
authors.forename: Alexander H
authors.initials: AH
authors.lastname: Rickard
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001120:Arginine / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D006801:Humans; D064307:Microbiota / Q000187:drug effects*; D012463:Saliva / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D001120:Arginine