Enhancement of fatty acid degradation pathway promoted glucoamylase synthesis in Aspergillus niger

Abstract

Background Our recent multi-omics analyses of glucoamylase biosynthesis in Aspergillus niger (A. niger) suggested that lipid catabolism was significantly up-regulated during high-yield period under oxygen limitation. Since the catabolism of fatty acids can provide energy compounds such as ATP and important precursors such as acetyl-CoA, we speculated that enhancement of this pathway might be beneficial to glucoamylase overproduction. Results Based on previous transcriptome data, we selected and individually overexpressed five candidate genes involved in fatty acid degradation under the control of the Tet-on gene switch in A. niger. Overexpression of the fadE, fadA and cyp genes increased the final specific enzyme activity and total secreted protein on shake flask by 21.3 ~ 31.3% and 16.0 ~ 24.2%, respectively. And a better inducible effect by doxycycline was obtained from early logarithmic growth phase (18 h) than stationary phase (42 h). Similar with flask-level results, the glucoamylase content and total extracellular protein in engineered strains OE-fadE (overexpressing fadE) and OE-fadA (overexpressing fadA) on maltose-limited chemostat cultivation were improved by 31.2 ~ 34.1% and 35.1 ~ 38.8% compared to parental strain B36. Meanwhile, intracellular free fatty acids were correspondingly decreased by 41.6 ~ 44.6%. The metabolomic analysis demonstrated intracellular amino acids pools increased 24.86% and 18.49% in two engineered strains OE-fadE and OE-fadA compared to B36. Flux simulation revealed that increased ATP, acetyl-CoA and NADH was supplied into TCA cycle to improve amino acids synthesis for glucoamylase overproduction. Conclusion This study suggested for the first time that glucoamylase production was significantly improved in A. niger by overexpression of genes fadE and fadA involved in fatty acids degradation pathway. Harnessing the intracellular fatty acids could be a strategy to improve enzyme production in Aspergillus niger cell factory.

Transcriptomic analyses reveal the potential antibacterial mechanism of citral against Staphylococcus aureus

“…A similar process was also found in other exogenous agents, such as betulinaldehyde (Chung et al, 2013). On the other hand, genes involved in the TCA cycle and fatty acid degradation pathway, which are the main ATP-producing pathways in the cell (Wang S. et al, 2021;Qi et al, 2022), were up-regulated. These findings suggested that S. aureus intended to promote the TCA cycle and fatty acid degradation pathway to overcome the ATP deficiency induced by citral.…”

Enhancement of protein production in Aspergillus niger by engineering the antioxidant defense metabolism

“…All strains were grown in Czapek-Dox media (CD) (including 0.05% agar powder). Before transformation, A. niger was cultured in the Dextrose Peptone Yeast extract media (DPY), and shake flask fermentations were conducted utilizing a specific fermentation medium [ 25 ]. For detailed compositions of all media used, please refer to the Supplementary Material (Table S1).…”

Preparation of layer‐assembled W/O/W‐type microencapsulated beads and application in solid‐state fermentation

“…Glucoamylase is primarily obtained from filamentous fungi such as Rhizopus , Aspergillus niger , and Aspergillus oryzae , among which the glucoamylase produced from A. niger has relatively high thermal stability (Nayab et al., 2022). Glucoamylase is an essential and high‐yield enzyme product widely used in the industrial production of alcohol, vinegar, starch, sugar, and so on (Qi et al., 2022). Free glucoamylase has poor stability, inactivation, heat, and acid resistance, whereas the emergence of immobilization technology has effectively improved the environmental tolerance of free glucoamylase (Danielli et al., 2022).…”

“…is an essential and high-yield enzyme product widely used in the industrial production of alcohol, vinegar, starch, sugar, and so on (Qi et al, 2022). Free glucoamylase has poor stability, inactivation, heat, and acid resistance, whereas the emergence of immobilization technology has effectively improved the environmental tolerance of free glucoamylase (Danielli et al, 2022).…”