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DOI: 10.1055/s-0034-1394593
Effect of oxidative stress on hypocrellin A yield in submerged cultures of endophytic Shiraia sp. A8
Hypocrellins are important photodynamic therapy agents for cancer diseases. A new hypocrellin A-producing strain, Shiraia sp. A8, was isolated from tissues of bamboo, Brachystachyum densiflorum [1, 2]. To determine the effect of oxidative stress on hypocrellin A yield of Shiraia sp. A8, we applied oxidative stress by inclusion of H2O2 (30µM) in the growth medium and by light exposure at 3000 Lx for 12h per day. The addition of H2O2 to submerged cultures resulted in an increase of catalase (CAT) and superoxide dismutase (SOD) activities during the exponential phase of growth and enhancement of hypocrellin A (256.6 mg/L, 2.5 fold) in comparison with the control. The reactive oxygen species (ROS) level in mycelium increased under light exposure by 12.4% and hypocrellin A was stimulated. However, the mycelia biomass was inhibited by continuous light exposure. When H2O2 at 30µM was applied to the submerged culture exposed to light on day 3, the hypocrellin A production was most effectively enhanced 3.7-fold (408.5 mg/L versus 110.04 mg/L in control) after 10 days culture.
Acknowledgements: This study is supported by PAPD and SRF for ROCS (No. K513201011).
Keywords: Shiraia sp. A8, hypocrellins, light exposure, H2O2, oxidative stress
References:
[1] Dong T, et al. 2012. Chinese Journal of Bioprocess Engineering 10(1): 25 – 29.
[2] Pan WS, et al. 2012. Chinese Journal of Bioprocess Engineering 10(6): 18 – 23.