High-efficiency biosynthesis of hypocrellin A in Shiraia sp using gamma-ray mutagenesis

Hypocrellin A (HA), well known as one of the best natural pigments and bioactive agent to treat skin diseases, is further anticipated to play a vital role in photodynamic therapy (PDT) in anticancer and antiviral treatments. In this study, an HA-producing strain ZZZ816 (Shiraia sp.) was isolated from the moso bamboo (Phyllostachys edulis) seeds, and gamma irradiation was used to mutagenize spores of the original strain. After treatment with cobalt-60 gamma (Co-60 gamma) with different doses (20, 50, 80, 100, 150, 180, 300, and 500 Gy), the 100 Gy was selected as the optimal condition, which led to 77.2 % lethality of spores and 35 % positive mutant frequency. The extracted compound of the most excellent HA-producing strain (H-4-2) was precisely analyzed by a combination of seven detection methods, and the maximum HA content was shown to reach 2018.3 mg/L. HA production in H-4-2 increased by 414.9 % compared to that of original strain ZZZ816 (392 mg/L) and was significantly higher than all the other industrial HA-producing strains in published reports.