Fast diagnostic tools such as near infrared spectroscopy have recently gained interest for bacterial identification. To avoid a process involving microbial pellet or suspension preparation from Petri dishes for NIR analysis, direct screening from agar in Petri dishes was explored. This two-step study proposes a new procedure for bacterial screening directly on agar plates with minimal nutrient medium bias. Firstly, principal component analyses showed optimal discrimination between the genera Lactobacillus, Pseudomonas and Brochothrix on different culture media, in transmission mode and with the bottom of Petri dishes facing the light source. The repeatability of spectra in these conditions was assessed with an average coefficient of variation inferior to 5% in the 12,500–3680 cm⁻¹ range. Secondly, 40 strains of Lactococcus and Enterococcus species were grown on Bennett agar and measured over a series of five assays. Principal component analyses highlighted better clustering according to genera and species and lower external bias while retaining the 8790–3680 cm⁻¹ spectral range and applying an extended multiplicative scatter correction with an average agar spectrum as a reference, in comparison to raw data and standard multiplicative scatter correction.

近来，诸如近红外光谱之类的快速诊断工具已引起细菌鉴定的兴趣。为避免涉及从陪替氏培养皿中进行微生物沉淀或悬浮液制备以进行近红外分析的过程，探索了直接从陪替氏培养皿中的琼脂中进行筛选的方法。这项分两步进行的研究提出了一种直接在琼脂平板上进行细菌筛查的新方法，所需的营养培养基偏差最小。首先，主成分分析表明，乳杆菌属，假单胞菌属和肉芽孢杆菌属之间存在最佳区分在不同的培养基上，以透射模式，培养皿的底部面向光源。在这些条件下，光谱的重复性在12,500–3680 cm ^-1范围内的平均变异系数低于5％。其次，在Bennett琼脂上生长40株乳球菌和肠球菌菌株，并通过一系列五项测定进行测量。主成分分析突出显示了根据属和种更好的聚类和较低的外部偏差，同时保留了8790–3680 cm ^-1的光谱范围，并且与原始数据和标准乘法相比，应用了以平均琼脂光谱为参考的扩展的乘法散射校正。散点校正。