Korpioja Miika-Erik, Sveholm Emmi, Dilokpimol Adiphol, Paasela Tanja, Kovalchuk Andriy
VTT Technical Research Centre of Finland Ltd, Tekniikantie 21, 02150, Espoo, Finland.
Biotechnol Biofuels Bioprod. 2025 Aug 8;18(1):89. doi: 10.1186/s13068-025-02688-5.
Industrial lignocellulosic side streams are considered an attractive carbon source for the cultivation of biotechnologically important fungi, although the presence of toxic pretreatment by-products is a major challenge yet to be overcome. Aspergillus oryzae is a filamentous fungus with a large secretion capacity, high tolerance for toxins, and a wide substrate range, making it a promising candidate for side stream utilization. In the present study, the cellular mechanisms of tolerance against furfural, 5-hydroxymethylfurfural (HMF), levulinic acid, ferulic acid, and vanillin were studied at the transcriptome level.
A. oryzae RIB40 was grown in the presence of different inhibitors commonly found in lignocellulosic side streams, and RNA sequencing was utilized to investigate the transcriptomic changes in response to the inhibitors. Analysis of the transcriptomic response in all conditions indicates that a large fraction of differentially expressed genes responded to the inhibitor-induced formation of reactive oxygen species (ROS). Apart from levulinic acid, all inhibitors showed strong initial suppression of metabolic pathways related to cell cycle, ribosome functions, protein folding, and sorting in the endoplasmic reticulum. Genes associated with cellular detoxification, namely, NAD(P)H-dependent oxidoreductases and efflux transporters, such as the ATP-Binding Cassette (ABC) transporters and major facilitator superfamily (MFS) transporters, showed strong upregulation upon exposure to the inhibitors.
The results obtained provide important insights into the stress response of A. oryzae to the xenobiotic compounds and their cellular detoxification. Aldehydic inhibitors, especially HMF, caused a strong and severe stress response in A. oryzae RIB40. Additionally, we identified several highly upregulated uncharacterized genes upon exposure to the inhibitors. These genes serve as promising targets for strain engineering to build robust industrial strains capable of utilizing lignocellulosic side streams as feedstock.
工业木质纤维素副产物被认为是用于培养具有生物技术重要性的真菌的有吸引力的碳源，尽管有毒预处理副产物的存在是一个尚未克服的主要挑战。米曲霉是一种丝状真菌，具有较大的分泌能力、对毒素的高耐受性和广泛的底物范围，使其成为利用副产物的有前景的候选者。在本研究中，在转录组水平上研究了对糠醛、5-羟甲基糠醛（HMF）、乙酰丙酸、阿魏酸和香草醛的耐受细胞机制。
米曲霉RIB40在木质纤维素副产物中常见的不同抑制剂存在下生长，并利用RNA测序研究对抑制剂的转录组变化。在所有条件下对转录组反应的分析表明，很大一部分差异表达基因对抑制剂诱导的活性氧（ROS）形成有反应。除了乙酰丙酸外，所有抑制剂对与细胞周期、核糖体功能、蛋白质折叠和内质网分选相关的代谢途径都有强烈的初始抑制作用。与细胞解毒相关的基因，即NAD（P）H依赖性氧化还原酶和外排转运蛋白，如ATP结合盒（ABC）转运蛋白和主要促进剂超家族（MFS）转运蛋白，在暴露于抑制剂后显示出强烈上调。
获得的结果为米曲霉对外源化合物的应激反应及其细胞解毒提供了重要见解。醛类抑制剂，尤其是HMF，在米曲霉RIB40中引起了强烈而严重的应激反应。此外，我们鉴定了暴露于抑制剂后几个高度上调的未表征基因。这些基因是菌株工程的有希望的目标，以构建能够利用木质纤维素副产物作为原料的强大工业菌株。
