Phospholipid and antioxidant responses of oleaginous fungus Cunninghamella echinulata against hydrogen peroxide stress.

Hydrogen peroxide (HO) is one of the major oxidative stress intracellularly and extracellularly, which may affect lipid membrane or cell membrane. However, the mechanism remains unclear. The present study investigated phospholipid and antioxidant responses of Cunninghamella echinulata under exogenous HO stress by integrating lipidomics and transcriptomics. HO significantly affected phospholipid profile of C. echinulata exposed to exogenous HO. The phospholipid content was reduced from 6.41% to 2.47% on the first day, and to 1.03% on the 7th day, which was 5-6 times lower than that in the control. Phosphatidyl choline was reduced significantly from 29.71% to 2.73% on the 7th day. The lipid-related metabolic maps of C. echinulata responding to HO were constructed based on transcriptomics, lipidomics and biochemical analysis. Results showed that HO almost mobilized all the signaling pathways in the cell, especially the AMPK and cAMP signaling pathway, which regulated the metabolism of proteins and fatty acids. HO-stress triggered the high expression of heat shock genes. The antioxidant enzymes were activated to supply more NADPH, which contributed to the modulation of intracellular redox balance, and continuously scavenged active substances, thus improving the mycelial resistance to oxidative stress.