title: Quantitative mapping of chlorhexidine in natural river biofilms.
abstract: Soft X-ray scanning transmission X-ray microscopy has been applied to map chlorhexidine, a ubiquitous antimicrobial agent, relative to major biochemical components (proteins, lipids, polysaccharides, Ca2+, K+, CO3(2-)) in natural river biofilms. For the first time, bio-accumulation of chlorhexidine in diatoms has been observed unambiguously. The quantitative results show that chlorhexidine bioaccumulated extensively in lipid-rich regions of diatoms and bacteria. Confocal laser scanning microscopy was used to document changes in the biofilm community. The bioaccumulation provides a significant entry point for chlorhexidine into the aquatic food chain. It results in modification of the biofilm community and it impacts the photosynthetic and protozoan species in particular. X-ray microscopy mapping at high spatial resolution is shown to be a powerful tool for studies of antimicrobial agents in the environment.
authors.affiliation: Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON, Canada L8S 4M1.
authors.forename: James J
authors.initials: JJ
authors.lastname: Dynes
authors.forename: John R
authors.initials: JR
authors.lastname: Lawrence
authors.forename: Darren R
authors.initials: DR
authors.lastname: Korber
authors.forename: George D W
authors.initials: GD
authors.lastname: Swerhone
authors.forename: Gary G
authors.initials: GG
authors.lastname: Leppard
authors.forename: Adam P
authors.initials: AP
authors.lastname: Hitchcock
mesh_terms: D000891:Anti-Infective Agents, Local / Q000032:analysis / Q000378:metabolism; D001419:Bacteria / Q000737:chemistry* / Q000378:metabolism; D018441:Biofilms; D002710:Chlorhexidine / Q000032:analysis* / Q000378:metabolism; D017377:Diatoms / Q000737:chemistry* / Q000378:metabolism; D004202:Disinfectants / Q000032:analysis / Q000378:metabolism; D008055:Lipids / Q000032:analysis; D008853:Microscopy / Q000379:methods; D009067:Mouthwashes / Q000032:analysis / Q000378:metabolism; D011134:Polysaccharides / Q000032:analysis; D011506:Proteins / Q000032:analysis; D045483:Rivers
chemical_list: D000891:Anti-Infective Agents, Local; D004202:Disinfectants; D008055:Lipids; D009067:Mouthwashes; D011134:Polysaccharides; D011506:Proteins; D002710:Chlorhexidine