State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, PR China.
Institute of Medical Sciences, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan, 250033, PR China.
Biosens Bioelectron. 2022 Sep 1;211:114378. doi: 10.1016/j.bios.2022.114378. Epub 2022 May 17.
Lactate, a hydroxycarboxylic acid commercially produced by microbial fermentation, is widely applied in diverse industrial fields. Lactate exists in two stereoisomeric forms (d-lactate and l-lactate). d-Lactate and l-lactate are often simultaneously present in many biological samples. Therefore, a biosensor able to detect both d- and l-lactate is required but previously unavailable. Herein, an allosteric transcription factor LldR from Pseudomonas aeruginosa PAO1, which responds to both d-lactate and l-lactate, was combined with amplified luminescent proximity homogeneous assay technology to develop a d,l-lactate biosensor. The proposed biosensor was optimized by mutation of DNA sequence in binding site of LldR. The optimized biosensor B-6 can accurately detect the concentration of lactate independent on ratio of the two isomers in pending test samples. The biosensor was also tentatively used in quantitative analysis of d-lactate, l-lactate, or d,l-lactate in fermentation samples produced by three recombinant strains of Klebsiella oxytoca. With its desirable properties, the biosensor B-6 may be a potential choice for monitoring the concentration of lactate during industrial fermentation.
乳酸是一种由微生物发酵生产的羟基羧酸，广泛应用于许多工业领域。乳酸有两种立体异构形式（d-乳酸和 l-乳酸）。d-乳酸和 l-乳酸通常同时存在于许多生物样本中。因此，需要一种能够同时检测 d-乳酸和 l-乳酸的生物传感器，但目前还没有这种传感器。本研究中，将假单胞菌 PAO1 中的变构转录因子 LldR 与扩增发光近同相分析技术相结合，开发了一种 d,l-乳酸生物传感器。通过突变 LldR 结合位点的 DNA 序列对所提出的生物传感器进行了优化。优化后的生物传感器 B-6 可以准确检测待测试样品中两种异构体比例无关的乳酸浓度。该生物传感器还初步用于定量分析三株产酸克雷伯氏菌重组菌株发酵样品中的 d-乳酸、l-乳酸或 d,l-乳酸。B-6 生物传感器具有良好的性能，可能是工业发酵过程中监测乳酸浓度的一种潜在选择。
