Abstract

L-asparaginase (ASNase) is an essential drug in the treatment of acute lymphoblastic leukemia (ALL). Commercial bacterial ASNases increase patient survival, but the consequent immunological reactions remain a challenge. Yeasts ASNase is closer to human congeners and could lead to lower side effects. Among 134 yeast strains isolated from marine-sediments in King George Island, Antarctica, nine were L-asparaginase producing yeasts and glutaminase-free. Leucosporidium muscorum CRM 1648 yielded the highest ASNase activity (490.41 U.L⁻¹) and volumetric productivity (5.12 U.L⁻¹ h⁻¹). Sucrose, yeast extract and proline were the best carbon and nitrogen sources to support growth and ASNase production. A full factorial design analysis pointed the optimum media condition for yeast growth and ASNase yield: 20 g L⁻¹ sucrose, 15 g L⁻¹ yeast extract and 20 g L⁻¹ proline, which resulted in 4582.5 U L⁻¹ and 63.64 U L⁻¹ h⁻¹ of ASNase and volumetric productivity, respectively. Analysis of temperature, pH, inoculum and addition of seawater indicated the best condition for ASNase production by this yeast: 12–15 °C, pH 5.5–6.5 and seawater >25% (v/v). Inoculum concentration seems not to interfere. This work is pioneer on the production of ASNase by cold-adapted yeasts, highlighting the potential of these microbial resources as a source of glutaminase-free L-asparaginase for commercial purposes.

抽象的

L-天冬酰胺酶（ASNase）是治疗急性淋巴细胞白血病（ALL）的必需药物。商业细菌ASNase可以提高患者的生存率，但是随之而来的免疫反应仍然是一个挑战。酵母中的ASNase更接近人类同源物，可能会降低副作用。从南极国王乔治岛海洋沉积物中分离的134个酵母菌株中，有9个是产生L-天冬酰胺酶的酵母和不含谷氨酰胺酶的酵母。粘膜白粉菌CRM 1648产生最高的ASNase活性（490.41 UL ^-1）和容积生产率（5.12 UL ^-1 h ^-1）。蔗糖，酵母提取物和脯氨酸是支持生长和ASNase产生的最佳碳和氮源。全因子设计分析指出酵母生长和产量ASNase最佳媒体条件：20克L- ^-1蔗糖15克L- ^-1酵母提取物和20克L- ^-1脯氨酸，这就造成了4582.5 UL ^-1和63.64 UL ^{- 1}小时^-1ASNase和容积生产率的关系。对温度，pH，接种物和海水的分析表明，该酵母生产ASNase的最佳条件是：12–15°C，pH 5.5–6.5，海水> 25％（v / v）。接种物浓度似乎没有干扰。这项工作是通过冷适应酵母生产ASNase的先驱，突显了这些微生物资源作为无谷氨酰胺酶L-天冬酰胺酶的商业用途的潜力。