基于单细胞拉曼光谱技术的葡萄球菌黄素生物合成分析

利用光镊拉曼光谱技术研究吲哚对金葡菌细胞中葡萄球菌黄素合成的抑制作用以及色素含量在分批培养过程中的动态变化。收集经不同浓度吲哚(终浓度为0,0.2,0.6,0.8,1.2和1.5 mmol/L)处理后的以及不同培养时间的金葡菌单细胞的拉曼光谱,以光谱1523 cm-1峰强度表征色素含量,并与紫外可见分光光度法得到的结果进行比较。结果表明,细菌拉曼光谱1523 cm-1峰强度与分光光度法测得的色素含量有良好的线性关系,相关系数达0.9772；群体和单细胞水平的光谱数据均表明,吲哚可剂量依赖性地抑制葡萄球菌黄素的合成,色素含量降低幅度超过70%；在分批培养中细菌色素含量在对数生长中期(12 h)达到最大值,各个时间点的群体内部细胞间色素含量的异质性较小,RSD在39.2%~61.1%之间。本研究表明光镊拉曼光谱技术是一种在单细胞水平分析葡萄球菌黄素含量的可靠方法。

Analysis of Staphyloxanthin Biosynthesis Using Single Cell Raman Spectroscopy

Laser tweezers Raman spectroscopy ( LTRS ) was used to study the inhibitory effect of indol on staphyloxanthin biosynthesis in Staphylococcus aureus cells and the dynamic changes of this pigment content inside bacterial cells during batch cultivation. The Raman spectra of Staphylococcus aureus cells cultivated for different time and exposed to various doses of indol were acquired. The intensity of 1523 cm-1 band was used for the quantification of staphyloxanthin, in the meantime, the pigment was measured by UV spectrometry. The experimental result showed that an excellent linear relationship existed between the intensities of Raman peak at 1523 cm-1 of bacterial cells and the pigment contents estimated by UV spectrometry, with a correlation coefficient of 0 . 9772 . The spectral data at population level as well as single cell level revealed that indol could inhibit the production of pigment in dose-dependent manner, and the pigment content in bacterial cells incubated with indol decreased by 70%. Under the batch growth condition, the pigment amount in Staphylococcus aureus cells reached the maximum value during the middle exponential growth phase ( 12 h ) and the heterogeneity of pigment content in bacterial cells within certain populations at various time points was relatively small, with RSDs of 39. 2% to 61. 1%. This investigation indicates that LTRS can be served as a reliable method for the analysis of staphyloxanthin content at single cell level.