Lopez-Moya Federico, Colom-Valiente Maria F, Martinez-Peinado Pascual, Martinez-Lopez Jesus E, Puelles Eduardo, Sempere-Ortells Jose M, Lopez-Llorca Luis V
Laboratory of Plant Pathology, Multidisciplinary Institute for Environmental Studies (MIES) Ramon Margalef, Department of Marine Sciences and Applied Biology, University of Alicante, E-03080 Alicante, Spain.
Laboratory of Medical Mycology, Faculty of Medicine, Miguel Hernández University, Sant Joan d'Alacant, Alicante, E-03550, Spain.
Fungal Biol. 2015 Mar;119(2-3):154-69. doi: 10.1016/j.funbio.2014.12.003. Epub 2014 Dec 24.
Chitosan permeabilizes plasma membrane and kills sensitive filamentous fungi and yeast. Membrane fluidity and cell energy determine chitosan sensitivity in fungi. A five-fold reduction of both glucose (main carbon (C) source) and nitrogen (N) increased 2-fold Neurospora crassa sensitivity to chitosan. We linked this increase with production of intracellular reactive oxygen species (ROS) and plasma membrane permeabilization. Releasing N. crassa from nutrient limitation reduced chitosan antifungal activity in spite of high ROS intracellular levels. With lactate instead of glucose, C and N limitation increased N. crassa sensitivity to chitosan further (4-fold) than what glucose did. Nutrient limitation also increased sensitivity of filamentous fungi and yeast human pathogens to chitosan. For Fusarium proliferatum, lowering 100-fold C and N content in the growth medium, increased 16-fold chitosan sensitivity. Similar results were found for Candida spp. (including fluconazole resistant strains) and Cryptococcus spp. Severe C and N limitation increased chitosan antifungal activity for all pathogens tested. Chitosan at 100 μg ml(-1) was lethal for most fungal human pathogens tested but non-toxic to HEK293 and COS7 mammalian cell lines. Besides, chitosan increased 90% survival of Galleria mellonella larvae infected with C. albicans. These results are of paramount for developing chitosan as antifungal.
壳聚糖可使质膜通透性增加，并杀死敏感的丝状真菌和酵母。膜流动性和细胞能量决定了真菌对壳聚糖的敏感性。葡萄糖（主要碳源）和氮的含量均降低五倍，会使粗糙脉孢菌对壳聚糖的敏感性提高两倍。我们将这种增加与细胞内活性氧（ROS）的产生和质膜通透性联系起来。尽管细胞内ROS水平很高，但将粗糙脉孢菌从营养限制状态中释放出来会降低壳聚糖的抗真菌活性。用乳酸代替葡萄糖时，碳和氮限制使粗糙脉孢菌对壳聚糖的敏感性比葡萄糖时进一步提高（四倍）。营养限制也会增加丝状真菌和酵母人类病原体对壳聚糖的敏感性。对于层出镰刀菌，将生长培养基中的碳和氮含量降低100倍，会使其对壳聚糖的敏感性提高16倍。念珠菌属（包括耐氟康唑菌株）和隐球菌属也有类似结果。严重的碳和氮限制会增加壳聚糖对所有测试病原体的抗真菌活性。100μg/ml的壳聚糖对大多数测试的人类真菌病原体具有致死性，但对HEK293和COS7哺乳动物细胞系无毒。此外，壳聚糖可使感染白色念珠菌的大蜡螟幼虫的存活率提高90%。这些结果对于将壳聚糖开发为抗真菌剂至关重要。
