Development of an enzymatic screening method for D-aspartate-producing lactic acid bacteria
Development of an enzymatic screening method for D-aspartate-producing lactic acid bacteria
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DOI：
10.1016/j.enzmictec.2021.109835
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发表时间：
2021-06-15
影响因子：
3.4
通讯作者：
Takahashi, Shouji
中科院分区：
文献类型：
--
作者：
Kajitani, Kengo;Ishikawa, Takumi;Takahashi, Shouji
D-天冬氨酸（D-Asp）是合成青霉素的重要中间体，也是一种内源性氨基酸，在动物（包括人类）的内分泌和神经系统中起重要作用。乳酸菌（LAB）已被用作人类的益生菌，一些LAB菌种产生D-Asp作为细胞壁肽聚糖的组分。因此，具有更高D-Asp产量的LAB菌株对于工业D-Asp生产是有价值的。本研究建立了一种D-Asp高产菌株的酶法筛选方法，并从中筛选出一株高产菌株。培养基中的D-天冬氨酸浓度的比色法估计高达4 mM使用D-天冬氨酸氧化酶（ChDDO）从酵母菌株UJ 1与辣根过氧化物酶耦合，虽然更准确的测定需要校正，因为干扰的培养基组分锰2+。我们从各种食品中分离出628株乳酸菌，并使用酶法D-Asp测定法筛选它们的D-Asp生产。筛选出13株产D-天冬氨酸的乳酸菌，分别属于乳酸菌属、左旋乳酸菌属、乳球菌属和肠球菌属。同一属、同一种的菌株产DAsp能力可能存在较大差异。一株命名为菌株WDN 19的菌株产生更高的D-Asp水平（1.84 mM），并且其与弯曲藻密切相关。这些结果表明，酶法筛选方法可快速、简便地鉴定和分离产D-Asp的LABs，为LABs生产D-Asp提供新的研究思路。
D-Aspartate (D-Asp) is an important intermediate for synthetic penicillin and an endogenous amino acid that plays important roles in the endocrine and nervous systems in animals including humans. Lactic acid bacteria (LABs) have been used as probiotics in humans, and some LAB species produce D-Asp as a component of cell wall peptidoglycan. LAB strains with greater D-Asp production would therefore be valuable for industrial D-Asp production. In this study, we developed an enzymatic screening method for D-Asp-producing LABs and isolated a strain with high D-Asp production. The D-Asp concentration in the culture medium was colorimetrically estimated up to 4 mM using D-aspartate oxidase (ChDDO) from the yeast Cryptococcus humicola strain UJ1 coupled with horseradish peroxidase, although a more accurate determination required correction because of interference by the medium component Mn2+. We isolated 628 LAB strains from various foods and screened them for D-Asp production using the enzymatic D-Asp assay method. The screening identified 13 D-Asp-producing LAB strains, which were suggested to belong to the genera Latilactobacillus, Levilactobacillus, Lactococcus, and Enterococcus. DAsp production ability was likely to widely differ among the strains in the same genera and species. One strain, named strain WDN19, produced much higher D-Asp levels (1.84 mM), and it was closely related to Latilactobacillus curvatus. These results indicated that the enzymatic screening method was useful for identifying and isolating D-Asp-producing LABs rapidly and easily, and it might provide novel findings regarding D-Asp production by LABs.