Effects of Spt7 knockout on growth and morphology of Aspergillus niger

Abstract:

As the core protein of a multifunctional protein complex Spt-Ada-Gcn5- acetyltransferase (SAGA) in yeast, Spt7 is not only responsible for maintaining the stability of the SAGA complex, but also responsible for the transcription of more than 10% of genes. However, there were few studies on the functions of Spt7 in filamentous fungi. [Objective] To investigate the effects of Spt7 on Aspergillus niger CGMCC 1062. [Methods] In this study, the plasmid with spt7 gene knockout was transferred into Aspergillus niger CGMCC 1062 by Agrobacterium tumefaciens transformation method. The colony morphology of Δspt7 strain and control group was observed, which grew on CM medium, different carbon sources, and H₂O₂-containing mediums. The relative transcription levels of glycolysis key genes and sporin-producing related genes were analyzed by real-time quantitative polymerase chain reaction (qRT-PCR). [Results] The Δspt7 strain was successfully obtained. It was found that the growth of Δspt7 strain was slow, the colony became white, and the sporulation was delayed. The knockout of the spt7 gene significantly affected the use of different carbon sources by the strain. However, Δspt7 strain and the control group grew normally on the plate with 20 mmol/L H₂O₂. The transcriptional levels of fbp, pfk, trk, pks, fda, and gsdA genes in the Δspt7 strain were 2.65 times, 4.46 times, 6.05 times, 4.90 times, 3.20 times, and 3.20 times lower than those in the control group, respectively. The transcriptional levels of wetA, abaA, and brlA were down-regulated by 529.93 times, 172.40 times, and 9.61 times, respectively, as compared with the control group. [Conclusion] The deletion of spt7 gene affects the normal growth, colony morphology, and conidial production of the strain.

Key words:Aspergillus niger;gene knockout;Δspt7 strain;colony morphology;anti-oxidative stress