Purification and characterization of protease enzyme from actinomycetes and its cytotoxic effect on cancer cell line (A549)

Objective: To isolate active actinomycetes from soil samples of Northern Himalayas and study their culture characterization, protease production and cytotoxic effects on cancer cell line (A549). Methods: Forty six strains of actinomycetes were isolated from the soil collected from Northern Himalayas, India. Isolation of actinomycetes was performed by serial dilution plate technique. Forty six isolated actinomycetes cultures were grown in ISP 2 medium to study the morphology and biochemical characteristics. Isolated strains were studied for protease enzyme production in skim milk agar medium with solubilising capacity. Seven isolates were studied for melanin pigmentation and different NaCl concentration. Effects of environmental conditions influencing protease enzyme production of seven isolated strains were also studied at different pH, temperature and metal ions (β-mercaptoethanol, dithiothreitol, iodoacetamide, MgSO₄, CaCl₂ and EDTA). The seven isolates were also studied for lytic enzyme activity using different bacteria and yeast such as Pseudomonas aeruginosa (P. aeruginosa), Enterococcus feacalis (E. feacalis), Escherishia coli (E. coli), Candida albicans (C. albicans), Bacillus subtilis (B. subtilis), Klebsiella pneumonia (K. pneumonia) and Staphylococcus aureus (S. aureus). Results: Isolates ERIA-31 and ERIA-33 produced more protease enzyme activity in modified nutrient agar media compared to other actinomycetes cultures. ERIA-31 and ERIA-33 were tested for cytotoxic effect in human adenocarcinoma cancer cell line (A549). IC₅₀ for ERIA-31 was 57.04 μg/mL and IC₅₀ for ERIA-33 was 55.07 μg/mL. Conclusion: Actinomycete being a protease producing bacteria has the potential for use in industrial purpose, pharmaceuticals, cytotoxic agent and its proteolytic activity. Isolates of ERIA-31 and ERIA-33 produced significant amount of protease enzymes.