Aranda-Martinez Almudena, Lopez-Moya Federico, Lopez-Llorca Luis Vicente
Laboratory of Plant Pathology, Department of Marine Sciences, Applied Biology, Multidisciplinary Institute for Environmental Studies Ramón Margalef, University of Alicante, Alicante, Spain.
J Basic Microbiol. 2016 Oct;56(10):1059-1070. doi: 10.1002/jobm.201500775. Epub 2016 Jun 3.
Chitosan antifungal activity has been reported for both filamentous fungi and yeast. Previous studies have shown fungal plasma membrane as main chitosan target. However, the role of the fungal cell wall (CW) in their response to chitosan is unknown. We show that cell wall regeneration in Neurospora crassa (chitosan sensitive) protoplasts protects them from chitosan damage. Caspofungin, a β-1,3-glucan synthase inhibitor, showed a synergistic antifungal effect with chitosan for N. crassa but not for Pochonia chlamydosporia, a biocontrol fungus resistant to chitosan. Chitosan significantly repressed N. crassa genes involved in β-1,3-glucan synthesis (fks) and elongation (gel-1) but the chitin synthase gene (chs-1) did not present changes in its expression. N. crassa cell wall deletion strains related to β-1,3-glucan elongation (Δgel-1 and Δgel-2) were more sensitive to chitosan than wild type (wt). On the contrary, chitin synthase deletion strain (Δchs-1) showed the same sensitivity to chitosan than wt. The mycelium of P. chlamydosporia showed a higher (ca. twofold) β-1,3-glucan/chitin ratio than that of N. crassa. Taken together, our results indicate that cell wall composition plays an important role on -sensitivity of filamentous fungi to chitosan.
壳聚糖对丝状真菌和酵母均具有抗真菌活性。先前的研究表明真菌质膜是壳聚糖的主要作用靶点。然而，真菌细胞壁（CW）在其对壳聚糖反应中的作用尚不清楚。我们发现粗糙脉孢菌（对壳聚糖敏感）原生质体中的细胞壁再生可保护它们免受壳聚糖的损伤。卡泊芬净是一种β-1,3-葡聚糖合酶抑制剂，对粗糙脉孢菌而言，它与壳聚糖具有协同抗真菌作用，但对壳聚糖抗性的生防真菌厚垣孢普可尼亚菌则没有这种作用。壳聚糖显著抑制了粗糙脉孢菌中参与β-1,3-葡聚糖合成（fks）和延伸（gel-1）的基因，但几丁质合酶基因（chs-1）的表达没有变化。与β-1,3-葡聚糖延伸相关的粗糙脉孢菌细胞壁缺失菌株（Δgel-1和Δgel-2）对壳聚糖比野生型（wt）更敏感。相反，几丁质合酶缺失菌株（Δchs-1）对壳聚糖的敏感性与wt相同。厚垣孢普可尼亚菌的菌丝体显示出比粗糙脉孢菌更高（约两倍）的β-1,3-葡聚糖/几丁质比率。综上所述，我们的结果表明细胞壁组成对丝状真菌对壳聚糖的敏感性起着重要作用。
