Isolation and identification of antioxidant producing marine-source actinomycetes and optimal medium conditions

Actinomycetes strain S-1 containing antioxidant components was isolated from the coast of Jeju Island in Korea and identified to the genus level using 16S ribosomal DNA sequencing and cellular fatty acids analysis as Nocardiopsis sp. (S-1). S-1 cultured supernatants showed high DPPH radical scavenging activities and hydroxyl radical scavenging abilities of up to 53%. Nutritional and culture conditions for antioxidant production were optimized. Galactose and yeast extracts were the best carbon and nitrogen sources for growth and antioxidant production. An initial medium acidity of pH 7.6, an incubation temperature of 25°C, a sodium chloride concentration of 2.5%, and an incubation time of 8 days were optimal. The DPPH scavenging activity of culture supernatants was 88% under optimum conditions. The S-1 strain can be useful for the functional fermented food and medicine industries.