Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
Microb Cell Fact. 2019 Jul 22;18(1):125. doi: 10.1186/s12934-019-1173-2.
Threonine is an essential amino acid that is extensively used in livestock industry as feed supplement due to its pronounced effect in improving the growth performance of animals. Application of genetically engineered bacteria for amino acid production has its share of controversies after eosinophils myalgia syndrome outbreak in 1980s. This has urged for continuous search for a food grade producer as a safer alternative for industrial amino acid production. Lactic acid bacteria (LAB) appear as an exceptional candidate owing to their non-pathogenic nature and reputation of Generally Recognized as Safe (GRAS) status. Recently, we have identified a LAB, Pediococcus pentosaceus TL-3, isolated from Malaysian food as a potential threonine producer. Thus, the objective of this study was to enhance the threonine production by P. pentosaceus TL-3 via optimized medium developed by using Plackett-Burman design (PBD) and central composite design (CCD).
Molasses, meat extract, (NH)SO, and MnSO were identified as the main medium components for threonine production by P. pentosaceus TL-3. The optimum concentration of molasses, meat extract, (NH)SO and MnSO were found to be 30.79 g/L, 25.30 g/L, 8.59 g/L, and 0.098 g/L respectively based on model obtained in CCD with a predicted net threonine production of 123.07 mg/L. The net threonine production by P. pentosaceus TL-3 in the optimized medium was enhanced approximately 2 folds compared to the control.
This study has revealed the potential of P. pentosaceus TL-3 as a safer alternative to produce threonine. Additionally, the current study has identified the key medium components affecting the production of threonine by P. pentosaceus TL-3, followed by optimization of their concentrations by means of statistical approach. The findings of this study could act as a guideline for the future exploration of amino acid production by LAB.
苏氨酸是一种必需氨基酸，由于其显著提高动物生长性能的作用，被广泛用作畜牧业的饲料添加剂。自 20 世纪 80 年代嗜酸性粒细胞肌痛综合征爆发以来，应用基因工程细菌生产氨基酸引起了广泛争议。这促使人们不断寻找一种食品级生产菌，作为工业氨基酸生产的更安全替代品。由于乳酸杆菌（LAB）具有非致病性和公认安全（GRAS）的美誉，因此它似乎是一种特殊的候选者。最近，我们从马来西亚食品中分离到一株 LAB，即戊糖片球菌 TL-3，鉴定其为潜在的苏氨酸生产菌。因此，本研究旨在通过使用 Plackett-Burman 设计（PBD）和中心复合设计（CCD）优化培养基来提高戊糖片球菌 TL-3 的苏氨酸产量。
确定了糖蜜、肉浸膏、（NH4）2SO4 和 MnSO4 是戊糖片球菌 TL-3 生产苏氨酸的主要培养基成分。根据 CCD 模型获得的最佳糖蜜、肉浸膏、（NH4）2SO4 和 MnSO4 浓度分别为 30.79g/L、25.30g/L、8.59g/L 和 0.098g/L，预测的净苏氨酸产量为 123.07mg/L。与对照相比，戊糖片球菌 TL-3 在优化培养基中的净苏氨酸产量提高了约 2 倍。
本研究揭示了戊糖片球菌 TL-3 作为生产苏氨酸的更安全替代品的潜力。此外，本研究还确定了影响戊糖片球菌 TL-3 生产苏氨酸的关键培养基成分，随后通过统计方法优化了它们的浓度。本研究的结果可为 LAB 未来探索生产氨基酸提供指导。
