Identification of an essential regulator controlling the production of raw-starch-digesting glucoamylase in .

BACKGROUND

Raw-starch-digesting glucoamylases (RSDGs) from filamentous fungi have great commercial values in starch processing; however, the regulatory mechanisms associated with their production in filamentous fungi remain unknown. HP7-1 isolated by our laboratory secretes RSDG with suitable properties but at low production levels. Here, we screened and identified novel regulators of RSDG gene expression in . through transcriptional profiling and genetic analyses.

RESULTS

HP7-1 transcriptomes in the presence of glucose and starch, respectively, used as the sole carbon source were comparatively analyzed, resulting in screening of 23 candidate genes regulating the expression of RSDG genes. Following deletion of 15 of the candidate genes in the parental . strain ∆, enzymatic assays revealed five mutants exhibiting significant reduction in the production of raw-starch-digesting enzymes (RSDEs). The deleted genes (, , , , and ), were the first report to regulate RSDE production of . . Further analysis revealed that ∆ lost the most RSDE production (83.4%), and that regulated the expression of major amylase genes, including the RSDG gene , a glucoamylase gene , and the α-amylase gene , during the late-stage growth of . .

CONCLUSION

Our results revealed a novel essential regulatory gene encoding a transcription factor in controlling the production of RSDE, regulating the expression of an important RSDG gene /, in . . These results provide insight into the regulatory mechanism of fungal amylolytic enzyme production.