Bioprocess development for L-asparaginase production by Streptomyces rochei, purification and in-vitro efficacy against various human carcinoma cell lines noura el-Ahmady el-naggar ✉ & nancy M. el-Shweihy in the near future, the demand for L-asparaginase is expected to rise several times due to an increase in its clinical and industrial applications in various industrial sectors, such as food processing. Streptomyces sp. strain NEAE-K is potent L-asparaginase producer, isolated and identified as new subsp. Streptomyces rochei subsp. chromatogenes neAe-K and the sequence data has been deposited under accession number KJ200343 at the GenBank database. Sixteen different independent factors were examined for their effects on L-asparaginase production by Streptomyces rochei subsp. chromatogenes NEAE-K under solid state fermentation conditions using Plackett-Burman design. pH, dextrose and yeast extract were the most significant factors affecting L-asparaginase production. Thus, using central composite design, the optimum levels of these variables were determined. L-asparaginase purification was carried out by ammonium sulfate followed by DEAE-Sepharose CL-6B ion exchange column with a final purification fold of 16.18. The monomeric molecular weight of the purified L-asparaginase was 64 kD as determined by SDS-PAGE method. The in vitro effects of L-asparaginase were evaluated on five human tumor cell lines and found to have a strong anti-proliferative effects. The results showed that the strongest cytotoxic effect of L-asparaginase was exerted on the HeLa and HepG-2 cell lines (ic 50 = 2.16 ± 0.2 and 2.54 ± 0.3 U/mL; respectively). In addition, the selectivity index of L-asparaginase against HeLa and HepG-2 cell lines was 3.94 and 3.35; respectively. L-asparaginase is one of the amidase group, that catalyzes the hydrolysis of L-asparagine and releases L-aspartic acid and ammonia 1. L-asparaginase is an effective therapeutic enzyme used in combination with other drugs for treating melanosarcoma, reticulosarbom, lymphocytic leukemia, Hodgkin disease, chronic lymphosarcoma, acute myelomonocytic leukemia, acute myelocytic leukemia and acute lymphoblastic leukemia in children and adults 2,3. In pediatric oncology, L-asparaginase is the recommended drug used for acute lymphoblastic leukemia therapy, resulting in a total recovery of more than 90 percent of kids within a period of four weeks 3. The anti-leukemic impact of L-asparaginase based on the fact that the tumor cells need a huge quantity of L-asparagine to survive. The tumor cells cannot synthesize L-asparagine for their needs because of the lack of L-asparagine synthetase and thus cannot synthesize the necessary proteins that rely on L-asparagine 4. The survival and growth of tumor cells rely on the exogenous source of L-asparagine (consumed in a diet, absorbed and accessible in the circulating pool) 5. Thus, injection of the enzyme into cancer patients intravenously decreases L-asparagine blood levels and selectively damages tumor cells 6. Conversely, the normal cell...