Jiménez-Gómez Irina, Valdés-Muñoz Gisell, Moreno-Perlin Tonatiuh, Mouriño-Pérez Rosa R, Sánchez-Carbente María Del Rayo, Folch-Mallol Jorge Luis, Pérez-Llano Yordanis, Gunde-Cimerman Nina, Sánchez Nilda Del C, Batista-García Ramón Alberto
Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca 62209, Morelos, Mexico.
Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada 22860, Baja California, Mexico.
J Fungi (Basel). 2020 Nov 27;6(4):316. doi: 10.3390/jof6040316.
Water activity (a) is critical for microbial growth, as it is severely restricted at a < 0.90. Saturating NaCl concentrations (~5.0 M) induce extreme water deprivation (a ≅ 0.75) and cellular stress responses. Halophilic fungi have cellular adaptations that enable osmotic balance and ionic/oxidative stress prevention to grow at high salinity. Here we studied the morphology, osmolyte synthesis, and oxidative stress defenses of the halophile EXF-12860 at 1.0 M and 5.13 M NaCl. Colony growth, pigmentation, exudate, and spore production were inhibited at NaCl-saturated media. Additionally, hyphae showed unpolarized growth, lower diameter, and increased septation, multicellularity and branching compared to optimal NaCl concentration. Trehalose, mannitol, arabitol, erythritol, and glycerol were produced in the presence of both 1.0 M and 5.13 M NaCl. Exposing cells to 5.13 M NaCl resulted in oxidative stress evidenced by an increase in antioxidant enzymes and lipid peroxidation biomarkers. Also, genes involved in cellular antioxidant defense systems were upregulated. This is the most comprehensive study that investigates the micromorphology and the adaptative cellular response of different non-enzymatic and enzymatic oxidative stress biomarkers in halophilic filamentous fungi.
水分活度（a）对微生物生长至关重要，因为在a < 0.90时其生长会受到严重限制。饱和NaCl浓度（约5.0 M）会导致极端的水分缺失（a ≅ 0.75）和细胞应激反应。嗜盐真菌具有细胞适应性，能够实现渗透平衡并预防离子/氧化应激，从而在高盐度环境中生长。在此，我们研究了嗜盐菌EXF-12860在1.0 M和5.13 M NaCl条件下的形态、渗透溶质合成及氧化应激防御机制。在NaCl饱和培养基中，菌落生长、色素沉着、渗出物及孢子产生均受到抑制。此外，与最佳NaCl浓度相比，菌丝表现出无极性生长、直径减小，且隔膜、多细胞性及分支增加。在1.0 M和5.13 M NaCl条件下均产生了海藻糖、甘露醇、阿拉伯糖醇、赤藓糖醇和甘油。将细胞暴露于5.13 M NaCl会导致氧化应激，这可通过抗氧化酶和脂质过氧化生物标志物的增加得以证明。此外，参与细胞抗氧化防御系统的基因被上调。这是一项最全面的研究，调查了嗜盐丝状真菌中不同非酶和酶促氧化应激生物标志物的微观形态及适应性细胞反应。
