Introduction. This study describes the identification and partial characterization of persistence-inducing factors (PIFs) from staphylococci. Hypothesis/Gap Statement. Increases in persisters during mid-log phase growth indicate that quorum-sensing factors might be produced by staphylococci. Aim. To identify and partially characterize PIFs from Staphylococcus epidermidis RP62A and Staphylococcus aureus SH1000. Methodology. Others have demonstrated a significant increase in persister numbers during mid-log phase. Inducers of this mid-log increase have yet to be identified in staphylococci. Optical density at 600 nm (OD600) was used instead of time to determine when persister numbers increased during logarithmic growth. Concentrated culture filtrates (CCFs) from S. epidermidis and S. aureus were obtained at various OD600s and following incubation at 16 h. The CCFs were used to develop a PIF assay. The PIF assay was used to partially characterize PIF from S. epidermidis and S. aureus for sizing of PIF activity, temperature and protease sensitivity and inter-species communications. Results. The optimal OD600s for S. epidermidis and S. aureus PIF assays were 2.0 and 0.5, respectively. The highest PIF activity for both species was from CCF following incubation overnight (16 h). S. epidermidis ’ PIF activity was decreased by storage at 4 oC but not at 20 oC (16 h), 37 oC (1 h) or 100 oC (15 min). S. aureus ’ PIF activity was decreased following storage at 4 oC (2 weeks) and after boiling at 100 oC for 5 min but not after incubation at 37 oC (1 h). PIF activity from both species went through a 3000 molecular weight cutoff ultrafilter. Proteinase K treatment of S. aureus PIF decreased activity but did not decrease the PIF activity of S. epidermidis . PIF from S. epidermidis did not increase persisters when used to treat S. aureus cells and nor did PIF from S. aureus increase persisters when used to treat S. epidermidis cells. Conclusions. Attempts to discover PIFs for staphylococci were unsuccessful due to the time-based means used to identify mid-log. Both staphylococcal species produce extracellular, low-molecular-weight inducers of persistence when assayed using an OD600 -based PIF assay.

中文翻译：

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表皮葡萄球菌和金黄色葡萄球菌中持久性细胞外诱导剂的检测和部分表征

介绍。本研究描述了来自葡萄球菌的持久诱导因子 (PIF) 的鉴定和部分表征。假设/差距陈述。在对数中期生长期间持久性的增加表明群体感应因子可能由葡萄球菌产生。目标。鉴定和部分表征来自表皮葡萄球菌RP62A 和金黄色葡萄球菌SH1000 的 PIF。方法。其他人已经证明在日志中期阶段持久性数量显着增加。尚未在葡萄球菌中鉴定这种对数中期增加的诱导物。600 nm 处的光密度 (OD 600 ) 代替时间来确定在对数增长期间持久性数量何时增加。来自表皮葡萄球菌和金黄色葡萄球菌的浓缩培养滤液 (CCF)在不同的 OD 600秒和孵育 16 小时后获得。CCF 用于开发 PIF 分析。PIF 测定用于部分表征来自表皮葡萄球菌和金黄色葡萄球菌的 PIF，以测定 PIF 活性、温度和蛋白酶敏感性以及种间通讯。结果。表皮葡萄球菌和金黄色葡萄球菌的最佳 OD 600 s PIF 测定分别为 2.0 和 0.5。两种物种的最高 PIF 活性来自 CCF 孵育过夜（16 小时）后。表皮葡萄球菌的 PIF 活性在 4 o C下储存会降低，但在 20 o C (16 h)、37 o C (1 h) 或 100 o C (15 min) 下则不会。S. aureus的 PIF 活性在 4 o C下储存（2 周）和在 100 o C 下煮沸5 分钟后降低，但在 37 o C 下孵育（1 小时）后没有降低。两种物种的 PIF 活性都通过了 3000 分子量截止超滤器。蛋白酶 K 处理金黄色葡萄球菌 PIF 降低了活性，但没有降低表皮葡萄球菌的 PIF 活性。PIF从表皮葡萄球菌用于治疗时，并没有增加，持久金黄色葡萄球菌细胞，也没有从没有PIF金黄色葡萄球菌用于治疗时，增加的持留表皮葡萄球菌细胞。结论。由于用于识别中间日志的基于时间的方法，发现葡萄球菌 PIF 的尝试没有成功。当使用基于 OD 600的 PIF 测定进行测定时，两种葡萄球菌物种都会产生细胞外、低分子量的持久性诱导剂。