title: Effects of Trp- and Arg-containing antimicrobial-peptide structure on inhibition of Escherichia coli planktonic growth and biofilm formation.
abstract: Biofilms are sessile microbial communities that cause serious chronic infections with high morbidity and mortality. In order to develop more effective approaches for biofilm control, a series of linear cationic antimicrobial peptides (AMPs) with various arginine (Arg or R) and tryptophan (Trp or W) repeats [(RW)(n)-NH(2), where n = 2, 3, or 4] were rigorously compared to correlate their structures with antimicrobial activities affecting the planktonic growth and biofilm formation of Escherichia coli. The chain length of AMPs appears to be important for inhibition of bacterial planktonic growth, since the hexameric and octameric peptides significantly inhibited E. coli growth, while tetrameric peptide did not cause noticeable inhibition. In addition, all AMPs except the tetrameric peptide significantly reduced E. coli biofilm surface coverage and the viability of biofilm cells, when added at inoculation. In addition to inhibition of biofilm formation, significant killing of biofilm cells was observed after a 3-hour treatment of preformed biofilms with hexameric peptide. Interestingly, treatment with the octameric peptide caused significant biofilm dispersion without apparent killing of biofilm cells that remained on the surface; e.g., the surface coverage was reduced by 91.5 + or - 3.5% by 200 microM octameric peptide. The detached biofilm cells, however, were effectively killed by this peptide. Overall, these results suggest that hexameric and octameric peptides are potent inhibitors of both bacterial planktonic growth and biofilm formation, while the octameric peptide can also disperse existing biofilms and kill the detached cells. These results are helpful for designing novel biofilm inhibitors and developing more effective therapeutic methods.
authors.affiliation: Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244, USA.
authors.forename: Shuyu
authors.initials: S
authors.lastname: Hou
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Liu
authors.forename: Anne W
authors.initials: AW
authors.lastname: Young
authors.forename: Sheron L
authors.initials: SL
authors.lastname: Mark
authors.forename: Neville R
authors.initials: NR
authors.lastname: Kallenbach
authors.forename: Dacheng
authors.initials: D
authors.lastname: Ren
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000235:genetics / Q000494:pharmacology*; D001120:Arginine / Q000235:genetics; D018441:Biofilms / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects*; D050296:Microbial Viability; D013329:Structure-Activity Relationship; D013997:Time Factors; D014364:Tryptophan / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D014364:Tryptophan; D001120:Arginine