Aspergillus niger is a cell factory widely used in industries to produce proteases, organic acids, drugs, and other substances. The hyphal morphology of A. niger is a complex differentiated elongated tubular structure, which limits its basic research and application. In this study, the mpkA , bck1 , steC , and Tpk2 genes were successfully deleted using a quick way to knock out genes based on the RNP (Ribonucleoprotein) complex. The study showed that the knockout of mpkA and bck1 kinase gene strains resulted in smaller, denser colonies, short rod-shaped hypha, and a significant increase in glucoamylase secretion. The mechanism of short hypha formation and high protein production for A. niger is the cell wall integrity signaling (CWIS) pathway. The CWIS pathway passed through the bck1 - mkkA - mpkA tertiary kinase to deliver phosphorylation signals to the rlmA transcription factor, which regulated the expression of the cell wall synthesis gene agsA , thus regulating hyphal morphology. The mpkA kinase regulated the expression of the transcription factor amyR , which affected the expression of the genes glaA and amyA , thus enhancing the expression of proteins in A. niger . This study provides a strategy for the regulation of hyphal morphology and promotes the application of A. niger in industrial production.
Haoying Zhang,Qi Zhang,Ting Zuo,Ziqi Wang,Jianmin Liao,Yuanyuan Lu
Candida albicans is an opportunistic pathogen, and the formation of its biofilm makes it resistant to traditional antifungal therapy. Anthraquinones have universal antibacterial activity. We evaluated the inhibitory effects of 2-chloromethyl anthraquinone on C. albicans adhesion, mycelial morphology transformation, and biofilm formation. The results showed that 2-chloromethyl anthraquinone could inhibit C. albicans adhesion, mycelium formation, and biofilm formation in a dose-dependent manner at 2 μg/mL. In addition, 2-chloromethyl anthraquinone significantly inhibited the expression of biofilm formation-related genes in C. albicans , including ALS1 , CPH1 , ECE1, HWP1 , TEC1 , BCR1 , and UME6 . In addition, Ras1-cAMP-Efg1 pathway-related genes ( RAC1 , CYR1 , and TPK2) were also significantly down-regulated, indicating that the inhibitory effect of 2-chloromethyl anthraquinone on C. albicans biofilms may be related to the Ras1-cAMP-Efg1 signaling pathway. In summary, the results of this study confirmed the inhibitory mechanism of 2-chloromethyl anthraquinone on the virulence factors of C. albicans , which laid a theoretical foundation for its use as an anti-biofilm agent against C. albicans .
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