Candida species are a major cause of human mucosal and deep tissue fungal infections, but few antifungal treatments are available. Here, we showed that lycosin-I, a peptide isolated from venom of the spider Lycosa singoriensis, acted as a potent antifungal inhibitor against Candida species. The MIC₅₀ values of lycosin-I reached 8 μg/mL to treat fluconazole-susceptible and fluconazole-resistant C. tropicalis isolates. Time-kill kinetics assays revealed that after a 2-hour exposure, lycosin-I reduced colony-forming units/mL in fluconazole-susceptible and fluconazole-resistant C. tropicalis isolates approximately 70%. Furthermore, salinity tolerance assays suggested that even in the presence of Mg²⁺, lycosin-I maintained its potent antifungal ability at a high concentration. When the concentration of lycosin-I was increased from 1 × MIC to 8 × MIC, a significant decrease of the biofilm metabolic activity was observed in both fluconazole-susceptible and fluconazole-resistant C. tropicalis isolates. Moreover, the biofilm inhibitory concentration 50 (BIC₅₀) and the biofilm eradicating concentration 50 (BEC₅₀) were approximately 32 μg/mL and 128 μg/mL, respectively. Confocal laser scanning microscopy showed the localization of CY5-labeled lycosin-I mainly in the cell cytoplasm, and lycosin-I was likely to be localized in the cytoplasm after its transportation across the cell wall and membrane. Overall, our work shows that lycosin-I is a potent antifungal agent with a high efficacy, a high salinity tolerance, and potent anti-biofilm properties.

念珠菌属是人类粘膜和深部组织真菌感染的主要原因，但很少有抗真菌治疗方法。在这里，我们显示了从蜘蛛辛科Lycosa singoriensis的毒液中分离出的一种肽lycosin-I是一种有效的针对念珠菌的抗真菌抑制剂。lycosin-I的MIC ₅₀值达到8μg/ mL，用于治疗易感氟康唑和耐氟康唑的热带梭菌。时间杀灭动力学分析显示，暴露2小时后，在fluconazole易感和fluconazole耐药的热带假丝酵母中，lycosin-I降低了菌落形成单位/ mL，大约分离了70％。此外，盐度耐受性测定表明即使存在镁²⁺，溶血素-1在高浓度下仍保持其有效的抗真菌能力。当lycosin-I的浓度从1×MIC增加到8×MIC时，在易感氟康唑和耐氟康唑的热带假丝酵母菌株中均观察到生物膜代谢活性的显着降低。此外，生物膜抑制浓度50（BIC ₅₀）和生物膜消除浓度50（BEC _50））分别约为32μg/ mL和128μg/ mL。共聚焦激光扫描显微镜显示CY5标记的lycosin-I主要定位在细胞质中，而lycosin-I穿过细胞壁和细胞膜转运后很可能位于细胞质中。总体而言，我们的工作表明，溶血素I是一种有效的抗真菌剂，具有高效，高耐盐性和有效的抗生物膜特性。