Differentiation of Bacterial Species in Liquid Culture Using Laser Speckle Contrast Imaging

Bacterial identification is vital for healthcare and environmental quality control. Traditional bacterial identification methods require extensive sample preparation, including cultivation, staining, and microscopy, making them time-consuming and labor-intensive. This study proposes the application of Laser Speckle Contrast Imaging (LSCI) as a novel approach to capture variations in speckle patterns between the start and end of the lag caused by changes in the shape and arrangement of bacterial cells during cell division in liquid cultures at lower cell concentrations, such as in the lag phase. Our approach offers an efficient alternative to traditional methods of bacterial species identification demonstrated with Escherichia coli and Micrococcus luteus pairs. Also, the differentiation of strains ( E. coli ATCC25922 and DH5α) is carried out based on the percentage change in speckle contrast between the end of lag and mid-log phase of their growth curve.