Single step purification of asparaginase from endophytic bacteria Pseudomonas oryzihabitans exhibiting high potential to reduce acrylamide in processed potato chips

This study reports the purification and characterization of extracellular asparaginase from an endophytic bacteria Pseudomonas oryzihabitans isolated from Hibiscus rosa-sinensis. Sixty endophytes isolated from medicinal plants H. rosa-sinensis, Withania somnifera and Ocimum sanctum were screened for their potential to produce asparaginase. Twenty seven isolates were found positive and exhibited asparaginase activity in the range of 0.6-2.3 U/mL. Isolate Hib-3 produced maximal level of asparaginase (2.1 U/mL) which was identified as P. oryzihabitans. The isolate under optimized culture conditions produced 4.3 U/mL of asparaginase with productivity of 238.9 U/L/h. Single step purification of asparaginase was achieved using SP sephadex cation exchange column. The purified asparaginase showed specific activity of 39 μmol min−1 mg protein−1 corresponding to 42 fold purification. Electrophoretic analysis indicated asparaginase to be heterodimer showing two bands of 54 and 50 kDa on SDS-PAGE, whereas, single band of 208.7 kDa was observed on Native-PAGE. Purified asparaginase was optimally active at pH 8.0 and 37-40 °C. Addition of purified asparaginase (2.8 U/g dried potato), reduced acrylamide (90%) in fried potatoes. In addition, the asparaginase was also found to exhibit anti-proliferative activity against MCF7-Breast and HeLa-Cervix carcinoma cell lines. This is the first report on purification of asparaginase from endophytic bacteria P. oryzihabitans isolated from H. rosa-sinensis.