Key Laboratory of Dairy Science, Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin 150030, China.
Key Laboratory of Dairy Science, Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin 150030, China.
J Dairy Sci. 2020 Aug;103(8):6882-6893. doi: 10.3168/jds.2019-17661. Epub 2020 Jun 3.
Due to the lack of electricity and thermostatic instruments in certain settings for convenient detection of Cronobacter species in powdered infant formula (PIF), a novel investigation was conducted to establish an electricity-free visual detection system for rapid detection of Cronobacter species in PIF. This system included a portable electricity-free heater that could use the exothermic reaction of calcium oxide and water and 3 kinds of phase change materials to supply 3 constant temperatures for immunomagnetic separation, DNA extraction, and loop-mediated isothermal amplification assay. Meanwhile, the amplified reaction combined with hydroxynaphthol blue could achieve rapid visual detection. Primers designed based on the 16S-23S ribosomal RNA internal transcribed spacer were used in loop-mediated isothermal amplification to specifically monitor Cronobacter species, and the detection limit can reach 4.2 × 10 cfu/g in PIF by an electricity-free heater in 2 h 30 min. Moreover, 2 h of pre-enrichment was necessary when the level of the PIF samples with Cronobacter spp. was 10 cfu/g. The stability of the system was evaluated in ambient temperature at 4°C, 25°C, and 37°C. The results suggested that the electricity-free heater can maintain 3 constant temperatures to support different processes. Therefore, this amplification and visual system is applicable for use in many fields for rapid and specific detection of Cronobacter species in PIF.
由于某些环境中缺乏电力和恒温仪器，难以方便地检测粉状婴儿配方食品（PIF）中的克罗诺杆菌属，因此进行了一项新的研究，以建立一种无需电力的目视检测系统，用于快速检测 PIF 中的克罗诺杆菌属。该系统包括一个便携式无电加热器，可利用氧化钙和水的放热反应以及 3 种相变材料为免疫磁分离、DNA 提取和环介导等温扩增反应提供 3 个恒温。同时，扩增反应与羟基萘酚蓝结合可实现快速目视检测。根据 16S-23S 核糖体 RNA 内部转录间隔区设计的引物用于环介导等温扩增，以特异性监测克罗诺杆菌属，通过无电加热器在 2 小时 30 分钟内可将 PIF 中的检测限达到 4.2×10 cfu/g。此外，当 PIF 样品中克罗诺杆菌属的水平为 10 cfu/g 时，需要进行 2 小时的预富集。在 4°C、25°C 和 37°C 的环境温度下评估了系统的稳定性。结果表明，无电加热器可以维持 3 个恒温，以支持不同的过程。因此，该扩增和可视化系统适用于许多领域，可用于快速、特异性检测 PIF 中的克罗诺杆菌属。
