Miyazawa Ken, Umeyama Takashi, Yoshimi Akira, Abe Keietsu, Miyazaki Yoshitsugu
Department of Fungal Infection, National Institute of Infectious Diseases.
Terrestrial Microbiology and Systematics, Graduate School of Global Environmental Studies, Kyoto University.
Med Mycol J. 2024;65(3):75-82. doi: 10.3314/mmj.24.007.
The hyphal surface of cells of filamentous fungi is covered with cell wall, which is mainly composed of polysaccharides. Since the cell wall is the first structure to come in contact with the infection host, the environment, and the fungus itself, the elucidation of the cell wall structure and biogenesis is essential for understanding fungal ecology. Among filamentous fungi, the genus Aspergillus is an important group in the industrial, food, and medical fields. It is known that Aspergillus species form hyphal pellets in shake liquid culture. The authors previously found the role of α-1,3-glucan in hyphal aggregation in Aspergillus species. In addition, extracellular polysaccharide galactosaminogalactan contributed to hyphal aggregation as well, and dual disruption of biosynthesis genes of α-1,3-glucan and galactosaminogalactan resulted in complete hyphal dispersion in shake liquid culture. The characteristic of mycelia to form pellets under liquid culture conditions was the main reason why the growth measurement methods used for unicellular organisms could not be applied. We reported that hyphal growth of the dual disruption mutant could be measured by optical density. A real-time plate reader could be used to determine the growth curve of the mycelial growth of the dual disruption mutant. This measurement approach not only provides basic microbiological insights in filamentous fungi, but also has the potential to be applied to high-throughput screening of anti-Aspergillus drugs.
丝状真菌细胞的菌丝表面覆盖着细胞壁，细胞壁主要由多糖组成。由于细胞壁是与感染宿主、环境以及真菌自身接触的首个结构，因此阐明细胞壁结构和生物合成对于理解真菌生态学至关重要。在丝状真菌中，曲霉属是工业、食品和医学领域的重要类群。已知曲霉属物种在摇瓶液体培养中形成菌丝球。作者之前发现了α-1,3-葡聚糖在曲霉属物种菌丝聚集过程中的作用。此外，胞外多糖半乳糖氨基半乳聚糖也有助于菌丝聚集，并且α-1,3-葡聚糖和半乳糖氨基半乳聚糖生物合成基因的双重破坏导致在摇瓶液体培养中菌丝完全分散。菌丝体在液体培养条件下形成球状体的特性是无法应用单细胞生物生长测量方法的主要原因。我们报道过双重破坏突变体的菌丝生长可以通过光密度来测量。实时酶标仪可用于测定双重破坏突变体菌丝生长的生长曲线。这种测量方法不仅能提供丝状真菌的基础微生物学见解，还具有应用于抗曲霉药物高通量筛选的潜力。
