茜草红素、紫草素及其衍生物(A/S)是产生于勿忘草科石油紫根(Lithospermum erythrorhizon Siebold & Zucc.)和紫草(Alkanna tinctoria (L.) Tausch)等植物根部的次生代谢物。这些萘醌类化合物具有抗癌、伤口愈合和抗微生物活性。为了研究从紫草中分离得到的内生细菌与A/S之间的相互作用，筛选了已知对这些化合物具有抗性的内生细菌，检测它们对液体培养基中的A/S的影响。然后，选择了假单胞菌Pseudomonas sp. R-72008菌株，并在营养基和以A/S为唯一碳源的微量培养基中测试其对A/S的改变能力。记录了细菌的生长情况，并利用高效液相色谱-二极管数组和超高效液相色谱-电喷雾离子化-质谱分析方法检测和定量代谢物。在接种了R-72008的营养基中，观察到A/S单体的数量减少，同时A/S寡聚体的数量增加。此外，在微量培养基中，初始A/S单体的显著减少与细菌的生长相关，首次显示出假单胞菌Pseudomonas sp. R-72008菌株能够利用萘醌类化合物A/S作为唯一的碳源。这项研究为细菌与植物抗菌剂之间的相互作用开辟了新的视角。版权所有2023年Rat, Koletti, Rodić, Papageorgiou, Willems and Assimopoulou.

Alkannin, shikonin and their derivatives (A/S) are secondary metabolites produced in the roots of certain plants of the Boraginaceae family such as Lithospermum erythrorhizon Siebold & Zucc. and Alkanna tinctoria (L.) Tausch. These naphthoquinones express anti-cancer, wound healing, and antimicrobial activities. To study the interactions between endophytic bacteria isolated from A. tinctoria and the antimicrobials A/S, endophytic bacteria known to be resistant to the compounds were screened for their effect on A/S in liquid medium. Thereafter, the strain Pseudomonas sp. R-72008, was selected and tested for its ability to modify A/S in nutrient medium and minimal medium with A/S as sole carbon source. Bacterial growth was recorded, and high performance liquid chromatography-diode array and ultra-high performance liquid chromatography-electrospray ionization-mass spectrometry analyses were performed to detect and quantify metabolites. In nutrient medium inoculated with R-72008, a decrease in the amount of A/S monomers initially present was observed and correlated with an increase of A/S oligomers. Moreover, a significant decrease of initial A/S monomers in minimal medium was correlated with bacterial growth, showing for the first time that a bacterial strain, Pseudomonas sp. R-72008, was able to use the naphthoquinones A/S as sole carbon source. This study opens new perspectives on the interactions between bacteria and plant antimicrobials.Copyright © 2023 Rat, Koletti, Rodić, Papageorgiou, Willems and Assimopoulou.