Industrial Bioprocess and Bioprospecting Laboratory (IBBL), Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana State, 502285, India.
Emerging Contaminants Group (ECG), Department of Civil Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana State, 502285, India.
Sci Rep. 2019 Feb 5;9(1):1423. doi: 10.1038/s41598-018-38094-1.
L-Asparaginase (L-asparagine aminohydrolase, E.C. 3.5.1.1) has been proven to be competent in treating Acute Lymphoblastic Leukaemia (ALL), which is widely observed in paediatric and adult groups. Currently, clinical L-Asparaginase formulations are derived from bacterial sources such as Escherichia coli and Erwinia chrysanthemi. These formulations when administered to ALL patients lead to several immunological and hypersensitive reactions. Hence, additional purification steps are required to remove toxicity induced by the amalgamation of other enzymes like glutaminase and urease. Production of L-Asparaginase that is free of glutaminase and urease is a major area of research. In this paper, we report the screening and isolation of fungal species collected from the soil and mosses in the Schirmacher Hills, Dronning Maud Land, Antarctica, that produce L-Asparaginase free of glutaminase and urease. A total of 55 isolates were obtained from 33 environmental samples that were tested by conventional plate techniques using Phenol red and Bromothymol blue as indicators. Among the isolated fungi, 30 isolates showed L-Asparaginase free of glutaminase and urease. The L-Asparaginase producing strain Trichosporon asahii IBBLA1, which showed the highest zone index, was then optimized with a Taguchi design. Optimum enzyme activity of 20.57 U mL was obtained at a temperature of 30 °C and pH of 7.0 after 60 hours. Our work suggests that isolation of fungi from extreme environments such as Antarctica may lead to an important advancement in therapeutic applications with fewer side effects.
L-天冬酰胺酶（L-天冬酰胺酰胺水解酶，E.C.3.5.1.1）已被证明能够有效治疗急性淋巴细胞白血病（ALL），ALL 在儿科和成人中均有广泛发现。目前，临床使用的 L-天冬酰胺酶制剂来源于细菌，如大肠杆菌和菊欧文氏菌。这些制剂在用于 ALL 患者时会引起多种免疫和过敏反应。因此，需要额外的纯化步骤来去除其他酶（如谷氨酰胺酶和脲酶）合并所产生的毒性。生产无谷氨酰胺酶和脲酶的 L-天冬酰胺酶是一个主要的研究领域。在本文中，我们报告了从南极的司各特山脉土壤和苔藓中分离筛选出的真菌，这些真菌产生的 L-天冬酰胺酶不含谷氨酰胺酶和脲酶。通过使用酚红和溴百里酚蓝作为指示剂的常规平板技术，从 33 个环境样本中获得了总共 55 个分离物。在分离出的真菌中，有 30 个分离物产生的 L-天冬酰胺酶不含谷氨酰胺酶和脲酶。其中，产 L-天冬酰胺酶的真菌里氏木霉 IBBLA1 的酶活最高，随后通过田口设计对其进行了优化。在 30°C 和 pH7.0 下，60 小时后获得了 20.57 U/mL 的最佳酶活。我们的工作表明，从南极等极端环境中分离真菌可能会在治疗应用方面取得重要进展，减少副作用。
