Radioprotective effects of Cordyceps militaris extracts on cells and DNA of Bacillus subtilis

Cordyceps is an intracellular parasite fungus in the Ascomycota group. Cordyceps militaris (C. militaris) has currently attracted considerable research attention as a potential source of immune enhancement and anti-radiation, thanks to its high antioxidant activity. The extract from Cordyceps militaris isolated and cultivated by the Radiation Technology Research Laboratory - Hanoi Irradiation Center was used as a radioprotector. The effects of C. military is extract on reducing cell and DNA damages at irradiated B. subtilis was estimated based on the survival rate of bacteria in the medium (NB) supplemented C. militaris extract (CM). From 0Gy to 1000Gy, the survival cell count of the bacteria in NB medium decreased from 10⁹ to 10⁶ CFU/ml. Meanwhile, the survival cell count of the bacteria in the NB medium supplemented with CM extract decreased from 10⁹ to 10⁷ CFU/ml. Besides, modifications in B. subtilis DNA after irradiation were investigated by gene amplification and 16S rRNA gene sequencing. The bioinformatic analysis of sequencing results showed that at dose of 300Gy, the rate of genetic modification of 16S rRNA dropped from 0.36% to 0%. At dose of 700Gy, it decreased from 1.49% to 0% and at dose of 1500 Gy, it decreased from 2.56% to 0.43%. The results confirmed the protective effects of the C. militaris extract on cells and DNA of B. subtilis B5. (author)