Antibacterial activity of a novel antimicrobial peptide [W7]KR12-KAEK derived from KR-12 against Streptococcus mutans planktonic cells and biofilms

Abstract

The aims of this study were to describe the synthesis of a novel synthetic peptide based on the primary structure of the KR-12 peptide and to evaluate its antimicrobial and anti-biofilm activities against Streptococcus mutans. The antimicrobial effect of KR-12 and [W⁷]KR12-KAEK was assessed by determining the minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations. The evaluation of anti-biofilm activity was assessed through total biomass quantification, colony forming unit counting and scanning electron microscopy. [W⁷]KR12-KAEK showed MIC and MBC values ranging from 31.25 to 7.8 and 62.5 to 15.6 μg ml⁻¹, respectively. Furthermore, [W7]KR12-KAEK significantly reduced biofilm biomass (50–100%). Regarding cell viability, [W⁷]KR12-KAEK showed reductions in the number of CFUs at concentrations ranging from 62.5 to 7.8 μg ml⁻¹ and 500 to 62.5 μg ml⁻¹ with respect to biofilm formation and preformed biofilms, respectively. SEM micrographs of S. mutans treated with [W⁷]KR12-KAEK suggested damage to the bacterial surface. [W⁷]KR12-KAEK is demonstrated to be an antimicrobial agent to control microbial biofilms.

Keywords:

• Antimicrobial peptide
• Streptococcus mutans
• biofilm
• dental caries

Funding

This work was supported by Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico (FUNCAP), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and Central Analítica-UFC/CT-INFRA/MCTI-SISNANO/Pró-Equipamentos CAPES. E. H. Teixeira is a member of the Brazilian Academy of Sciences.