CFU Imaging and Counting for Bacterial Studies

Bacterial populations grown in a lab environment are typically seen as homogeneous in terms of growth rate, size, and content. However, recent findings have shown that even during exponential growth phase, these cells can be heterogeneous. This has important consequences for how bacteria respond to stressors such as antibiotics. For example, the concept of antimicrobial persistence is linked to a small subpopulation of cells that enter a dormant state where antibiotics are no longer effective. While methods exist for identifying non-growing cells in bacterial cultures, less attention has been paid to how these cells may affect growth on solid surfaces. To address this, a low-cost, open-source platform has been developed to analyze bacterial colony growth on multiple agar plates simultaneously. The system includes a temperature-controlled chamber, high-resolution scanner, and software for extracting and plotting colony lag time and growth kinetics. The system was tested using a wild-type strain of E. coli and has the potential to provide new insights into understanding the impact of microbial heterogeneity on antibiotic resistance and persistence.