A time-series transcriptomic changes of Streptococcus mutans in response to heat stress

Dental caries are closely associated with the virulence of Streptococcus mutans. The virulence expression of S. mutans is linked to its stress adaptation to the changes in the oral environment. In this work we used whole-genome microarrays to profile the dynamic transcriptomic responses of S. mutans during physiological heat stress. In addition, we evaluated the phenotypic changes, including initial biofilm formation, acid production and ATP turnover of S. mutans during heat stress. There were distinct patterns observed in the way that S. mutans responded to heat stress that included 66 transcription factors for the expression of functional genes being differentially expressed. Especially, response regulators of two component systems (TCSs), the repressors of heat shock proteins and regulators involved in sugar transporting and metabolism co-ordinated to enhance the cell’s survival and energy generation against heat stress in S. mutans. S. mutans UA159 whole-genome arrays (8 x 15 K) were obtained from Agilent and included 1997 probes for S. mutans transcripts. We used time series microarrays to detect the dynamic changes of S. mutans under heat stress. For the exposure to heat stress, cultures of S. mutans (OD600nm=0.5) were transferred from 37℃ to a 45℃ water bath, the temperature of each culture was raised to 42℃ in < 4 min. Then the cultures were transferred to a 42℃ water bath for 5 min, 10 min, 15 min, 30 min, 45 min and 60 min. The control was a cell culture grown at 37℃ and collected before transferred to 45℃ water bath.

龋病（Dental caries）与变形链球菌（Streptococcus mutans）的毒力密切相关。变形链球菌的毒力表达与其对口腔环境变化的应激适应息息相关。本研究采用全基因组微阵列（whole-genome microarrays）技术，解析变形链球菌在生理性热应激下的动态转录组应答特征。此外，本研究还评估了热应激条件下变形链球菌的表型变化，包括初始生物被膜形成、产酸能力与ATP周转情况。研究发现，变形链球菌对热应激的应答存在独特模式，其中66个参与功能基因表达的转录因子呈现差异表达。尤为关键的是，双组分系统（two component systems, TCSs）的应答调节因子、热休克蛋白（heat shock proteins）的阻遏蛋白，以及参与糖转运与代谢的调节因子协同作用，以增强变形链球菌在热应激下的细胞存活能力与能量生成效率。本研究使用的变形链球菌UA159全基因组微阵列芯片（8×15 K）购自安捷伦（Agilent），该芯片包含1997个针对变形链球菌转录本的探针。本研究采用时间序列微阵列技术，检测热应激下变形链球菌的动态变化。热应激处理组的变形链球菌菌液（OD600nm=0.5）从37℃转移至45℃水浴环境，菌液温度在4分钟内升至42℃；随后将菌液转移至42℃水浴环境，分别培养5、10、15、30、45及60分钟后取样。对照组为在37℃下培养、且在转移至45℃水浴前收集的菌液。