Characterization and applications of protease inhibitor compound from marine yeast Candida orthopsilosis KSSB3

The current study was planned to screen the marine yeasts for the protease inhibitor production and to investigate its antibacterial and antioxidant activity. Among the 30 marine yeast isolates recovered from the backwater of Port Blair, Andaman-Nicobar Islands, only 4 isolates showed positive protease inhibition activity. The crude extract of the isolate KSSB3 showed 62.51% inhibition activity while the ethyl acetate extract of this isolate KSSB3 showed 59.8% inhibition activity. Medium optimization studies were carried out for better protease inhibitor production by altering various physical and chemical parameters like temperature, pH, salinity, different carbon and nitrogen sources. The optimum condition was observed at 37 degrees C, pH 2, 15% NaCl concentration, glucose as a carbon source and casein as a nitrogen source. Structural elucidation of the potential compound was performed using HPLC, FT-IR and GC-MS analysis. Antioxidant activity was performed to check the free radical scavenging activity of the compound. It showed good antioxidant activity in DPPH, metal chelating and hydrogen peroxide scavenging assays. Antibacterial activity was also checked for the isolate KSSB3 where it showed good antibacterial activity (22 mm) against Staphylococcus aureus. The potential yeast isolate KSSB3 was identified as Candida orthopsilosis KSSB3 strain through 18s rRNA sequencing.