Production and Characterization of L-Asparaginases of Streptomyces Isolated from the Arauca Riverbank (Colombia)

Abstract

Introduction: L-asparaginase, is known as an anti-cancer agent, mainly used in acute lymphoblastic leukemia, which prevents the proliferation of tumor cells. This study shows that there are unexplored regions in Colombia that can be sources of obtaining this enzyme and that the optimization of the production of L-asparaginase from native isolates can be determined in the search for alternatives to commercial drugs.

Materials and Methods: Selection and identification of Streptomyces among Actinobacteria isolated from the Arauca riverbank for L-asparaginase producers are described. In addition, the effect of carbon and nitrogen sources, pH, temperature and agitation rate are studied for L-asparaginase activity in liquid culture using Plackett-Burman design and Taguchi methodology. Kinetic characterization of a purified L-asparaginase and its cytotoxic potential are evaluated too.

Results: Seven of seventy-eight actinobacterial strains were selected as L-asparaginase producing Streptomyces showing a high L-asparaginase/L-glutaminase ratio in liquid culture with lactose as substrate. The strain 112 identified as Streptomyces lacticiproducens was chosen for L-asparaginase production at these culture conditions: lactose 0.25%, L-asparagine 0,015%, malt extract 0,015%, pH 7.36, 32°C and 130 rpm. Enzymatic studies of the purified L-asparaginase showed that the optimal pH and temperature were 6 and 37.5°C, respectively. This purified enzyme had an IC50 of 36.74 µg/mL on THP-1 cells.

Conclusion: S. lacticiproducens isolated from the Arauca riverbank is a new source for the production of a high activity L-asparaginase, creating expectation of its availability as a drug for the acute lymphoblastic leukemia treatment.