Fatty-acid profiles and expression of the fabM gene in a fluoride-resistant strain of Streptococcus mutans
Objective: The aim of this study was to compare the membrane fatty acid profile and expression of the fabM gene in a fluoride-resistant Streptococcus mutans strain with those of its wild-type counterpart. Additionally, we aimed to investigate whether mutations were present in the fabM gene of the fluoride-resistant strain. Design: A fluoride-resistant strain of S. mutans was obtained by step-by-step induction in vitro. The fluoride-resistant strain and its wild-type counterpart were grown anaerobically in a brain heart infusion broth, harvested and resuspended in a salt solution for an acid survival assay and a pH-drop experiment. The membrane fatty acid profile was determined by gas chromatography-mass spectrometry. Expression of the fabM gene was quantified by realtime PCR. The fabM gene was also sequenced. Results: The ability of the fluoride-resistant strain to resist acid stress was greater than that of the wild-type strain. A significant difference in the amount of long-chain monounsatu-rated fatty acids between the fluoride-resistant strain and the wildtype strain was detected in acidic condition (P < 0.01). In addition, the level of fabM mRNA in the fluoride-resistant strain was significantly higher than that of the wild-type strain in the acidic condition as well (P < 0.01). However, the sequence of the fabM gene from the fluoride-resistant strain was 100％ homologous with that from the wild-type strain. Conclusions: The membrane fatty acid profile and expression of the fabM gene in the fluoride-resistant strain were altered compared to the wild-type strain in acidic conditions, but no differences were found in the sequence of the fabM gene.
Streptococcus mutans Fluoride-resistant strain Membrane fatty acid fabM gene Acid tolerance
Laikuan Zhu Zhimin Zhang Jingping Liang
Department of Endodontics and Operative Dentistry, Ninth Peoples Hospital, Shanghai Jiao Tong Unive Department of Endodontics and Operative Dentistry, School of Stomatology, Jilin University, No. 1500 Department of Endodontics and Operative Dentistry, Ninth Peoples Hospital, Shanghai Jiao Tong Unive
国际会议
上海
英文
295-299
2011-12-28（万方平台首次上网日期，不代表论文的发表时间）