The Application of a Recombinant Antimicrobial Peptide of Thrombocidin-1 Expressed in Pichia pastoris as a Novel Approach Against Some Oral Pathogenic Bacteria: An In Vitro Study

Abstract

Objective: Oral infections and dental caries are considered serious health problems. Therefore, searching for new agents with antimicrobial properties seems to be crucial. This study aimed to evaluate the antimicrobial activity of the recombinant Thrombocidin-1 [TC-1] peptide on some oral pathogens. Also, the cytotoxicity of this peptide on human gingival fibroblast cells was investigated.

Methods: In this study, Pichia pastoris was used for the expression of recombinant TC-1. The microbroth dilution method was used to determine the minimum inhibitory concentration [MIC] and minimum bacterial concentration [MBC]. It tested against four main oral pathogens; Streptococcus mutans, Streptococcus salivarius, Streptococcus oralis, and Enterococcus faecalis. Moreover, the cytotoxicity analysis was done on gingival fibroblast cells by the MTT method. The data were analyzed using a two-way analysis of variance [ANOVA] and Tukey's HSD tests.

Results: The most bactericidal effect of TC-1 was against S. salivarius, the highest bacteriostatic effect was against S. salivarius, and S. oralis had the lowest MIC value of 1.512 μg/ml. The Thrombocidin- 1 peptide showed lower antibacterial properties against E. faecalis compared with CHX, unlike the stronger antimicrobial effect on examined streptococci. According to cytotoxicity examination, no concentration of TC-1 presented over 50% growth inhibition [IC50] of the fibroblasts cells.

Conclusion: Based on antimicrobial tests and cytotoxicity results, the Thrombocidin-1 peptide may be useful as a safe antibacterial agent against some oral pathogens in dental materials.

Keywords: Antimicrobial peptide; E. faecalis; Streptococus mutans; Thrombocidin-1; antibacterial; cytotoxicity.