Ceresa Chiara, Rinaldi Maurizio, Chiono Valeria, Carmagnola Irene, Allegrone Gianna, Fracchia Letizia
Department of Pharmaceutical Sciences, Università del Piemonte Orientale "A. Avogadro", Largo Donegani 2, 28100, Novara, Italy.
Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy.
Antonie Van Leeuwenhoek. 2016 Oct;109(10):1375-88. doi: 10.1007/s10482-016-0736-z. Epub 2016 Jul 21.
Candida albicans is the major fungus that colonises medical implants, causing device-associated infections with high mortality. Antagonistic bacterial products with interesting biological properties, such as biosurfactants, have recently been considered for biofilm prevention. This study investigated the activity of lipopeptide biosurfactant produced by Bacillus subtilis AC7 (AC7 BS) against adhesion and biofilm formation of C. albicans on medical-grade silicone elastomeric disks (SEDs). Chemical analysis, stability, surface activities of AC7 BS crude extract and physicochemical characterisation of the coated silicone disk surfaces were also carried out. AC7 BS showed a good reduction of water surface tension, low critical micelle concentration, good emulsification activity, thermal resistance and pH stability. Co-incubation with 2 mg ml(-1) AC7 BS significantly reduced adhesion and biofilm formation of three C. albicans strains on SEDs in a range of 67-69 % and of 56-57 %, respectively. On pre-coated SEDs, fungal adhesion and biofilm formation were reduced by 57-62 % and 46-47 %, respectively. Additionally, AC7 BS did not inhibit viability of C. albicans strains in both planktonic and sessile form. Chemical analysis of the crude extract revealed the presence of two families of lipopeptides, principally surfactin and a lower percentage of fengycin. The evaluation of surface wettability indicated that AC7 BS coating of SEDs surface was successful although uneven. AC7 BS significantly prohibits the initial deposition of C. albicans and slows biofilm growth, suggesting a potential role of biosurfactant coatings for preventing fungal infection associated with silicone medical devices.
白色念珠菌是主要定植于医用植入物的真菌，可导致与器械相关的感染，死亡率很高。具有有趣生物学特性的拮抗菌产物，如生物表面活性剂，最近已被考虑用于预防生物膜。本研究调查了枯草芽孢杆菌AC7（AC7 BS）产生的脂肽生物表面活性剂对白色念珠菌在医用级硅橡胶弹性体圆盘（SEDs）上的黏附及生物膜形成的活性。还对AC7 BS粗提物进行了化学分析、稳定性、表面活性研究以及对涂覆硅橡胶圆盘表面进行了物理化学表征。AC7 BS表现出良好的降低水表面张力的能力、低临界胶束浓度、良好的乳化活性、耐热性和pH稳定性。与2 mg ml⁻¹的AC7 BS共同孵育可显著降低三种白色念珠菌菌株在SEDs上的黏附和生物膜形成，分别降低67 - 69%和56 - 57%。在预先涂覆的SEDs上，真菌黏附和生物膜形成分别降低了57 - 62%和46 - 47%。此外，AC7 BS对浮游态和固着态的白色念珠菌菌株的活力均无抑制作用。粗提物的化学分析表明存在两类脂肽，主要是表面活性素，丰原素的比例较低。表面润湿性评估表明，SEDs表面的AC7 BS涂层虽不均匀但很成功。AC7 BS显著抑制白色念珠菌的初始沉积并减缓生物膜生长，表明生物表面活性剂涂层在预防与硅橡胶医疗器械相关的真菌感染方面具有潜在作用。
