Filamentous fungi are excellent lignocellulose degraders, which they achieve through producing carbohydrate active enzymes (CAZymes). CAZyme production is highly orchestrated and gene expression analysis has greatly expanded understanding of this important biotechnological process. The thermophilic fungus Thermoascus aurantiacus secretes highly active thermostable enzymes that enable saccharifications at higher temperatures; however, the genome-wide measurements of gene expression in response to CAZyme induction are not understood. A fed-batch system with plant biomass-derived sugars d-xylose, l-arabinose and cellobiose established that these sugars induce CAZyme expression in T. aurantiacus. The C5 sugars induced both cellulases and hemicellulases, while cellobiose specifically induced cellulases. A minimal medium formulation was developed to enable gene expression studies of T. aurantiacus with these inducers. It was found that d-xylose and l-arabinose strongly induced a wide variety of CAZymes, auxiliary activity (AA) enzymes and carbohydrate esterases (CEs), while cellobiose facilitated lower expression of mostly cellulase genes. Furthermore, putative orthologues of different unfolded protein response genes were up-regulated during the C5 sugar feeding together with genes in the C5 sugar assimilation pathways. This work has identified two additional CAZyme inducers for T. aurantiacus, l-arabinose and cellobiose, along with d-xylose. A combination of biochemical assays and RNA-seq measurements established that C5 sugars induce a suite of cellulases and hemicellulases, providing paths to produce broad spectrum thermotolerant enzymatic mixtures.

中文翻译：

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来自嗜热真菌 Thermoascus aurantiacus 的 CAZymes 由 C5 和 C6 糖诱导

丝状真菌是出色的木质纤维素降解剂，它们通过产生碳水化合物活性酶 (CAZymes) 来实现。CAZyme 生产是高度协调的，基因表达分析极大地扩展了对这一重要生物技术过程的理解。嗜热真菌 Thermoascus aurantiacus 分泌高活性的热稳定酶，可以在更高的温度下进行糖化；然而，对响应 CAZyme 诱导的基因表达的全基因组测量尚不清楚。具有植物生物质衍生糖类 d-木糖、l-阿拉伯糖和纤维二糖的补料分批系统确定，这些糖类可诱导 T. aurantiacus 中的 CAZyme 表达。C5 糖诱导纤维素酶和半纤维素酶，而纤维二糖特异性诱导纤维素酶。开发了一种基本培养基配方，以便能够使用这些诱导剂对 T. aurantiacus 进行基因表达研究。发现 d-木糖和 l-阿拉伯糖强烈诱导多种 CAZymes、辅助活性 (AA) 酶和碳水化合物酯酶 (CE)，而纤维二糖促进主要纤维素酶基因的低表达。此外，在 C5 糖与 C5 糖同化途径中的基因一起喂养期间，不同未折叠蛋白反应基因的推定直系同源物被上调。这项工作已经确定了两种额外的 CAZyme 诱导剂，用于 T. aurantiacus、l-阿拉伯糖和纤维二糖，以及 d-木糖。生化测定和 RNA-seq 测量的组合确定 C5 糖诱导一组纤维素酶和半纤维素酶，