Tong Zhongchun, Zhang Luodan, Ling Junqi, Jian Yutao, Huang Lijia, Deng Dongmei
Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, Guangdong, China; Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, Guangdong, China.
Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, Guangdong, China.
PLoS One. 2014 Jun 17;9(6):e99513. doi: 10.1371/journal.pone.0099513. eCollection 2014.
Free D-amino acids (D-AAs) are one of the most striking features of the peptidoglycan composition in bacteria and play a key role in regulating and disassembling bacterial biofilms. Previous studies have indicated that the antimicrobial peptide nisin can inhibit the growth of the cariogenic bacteria Streptococcus mutans. The present study investigated the effect of free amino acids either alone or in combination with nisin on biofilm and on planktonic S. mutans bacteria. The results of the MIC and MBC analyses showed that D-cysteine (Cys), D- or L-aspartic acid (Asp), and D- or L-glutamic acid (Glu) significantly improve the antibacterial activity of nisin against S. mutans and that the mixture of D-Cys, D-Asp, and D-Glu (3D-AAs) and the mixture of L-Cys, L-Asp, and L-Glu (3L-AAs) at a concentration of 40 mM can prevent S. mutans growth. Crystal violet staining showed that the D- or L-enantiomers of Cys, Asp, and Glu at a concentration of 40 mM can inhibit the formation of S. mutans biofilms, and their mixture generated a stronger inhibition than the components alone. Furthermore, the mixture of the three D-AAs or L-AAs may improve the antibacterial activity of nisin against S. mutans biofilms. This study underscores the potential of free amino acids for the enhancement of the antibacterial activity of nisin and the inhibition of the cariogenic bacteria S. mutans and biofilms.
游离D-氨基酸（D-AAs）是细菌肽聚糖组成中最显著的特征之一，在调节和分解细菌生物膜中起关键作用。先前的研究表明，抗菌肽乳链菌肽可以抑制致龋菌变形链球菌的生长。本研究调查了游离氨基酸单独或与乳链菌肽联合使用对生物膜和浮游变形链球菌的影响。最低抑菌浓度（MIC）和最低杀菌浓度（MBC）分析结果表明，D-半胱氨酸（Cys）、D-或L-天冬氨酸（Asp）以及D-或L-谷氨酸（Glu）可显著提高乳链菌肽对变形链球菌的抗菌活性，并且浓度为40 mM的D-半胱氨酸、D-天冬氨酸和D-谷氨酸混合物（3D-AAs）以及L-半胱氨酸、L-天冬氨酸和L-谷氨酸混合物（3L-AAs）可抑制变形链球菌生长。结晶紫染色显示，浓度为40 mM的半胱氨酸、天冬氨酸和谷氨酸的D-或L-对映体可抑制变形链球菌生物膜的形成，且它们的混合物产生的抑制作用比单独的成分更强。此外，三种D-氨基酸或L-氨基酸的混合物可能会提高乳链菌肽对变形链球菌生物膜的抗菌活性。本研究强调了游离氨基酸在增强乳链菌肽抗菌活性以及抑制致龋菌变形链球菌和生物膜方面的潜力。
