To find a needle in a haystack, make the haystack 2D
Finding solitary bacteria with desired properties among millions of other cells is like looking for a needle in a haystack. At present, this task is commonly accomplished using one-dimensional flow cytometry that analyzes individual cells in sequence, one each in a moment. The Chetverin group describes an alternative two-dimensional approach. Using the novel method of merged gels, they prepare a monolayer of immobilized bacterial cells containing up to 100,000 cells per square millimeter. This allows thousands of cells in a microscope field to be analyzed simultaneously, thereby providing for screening rates characteristic of flow cytometry. The image analysis enabled by the 2D format allows cells to be distinguished from each other and from non-cellular particles, such as dust, thereby increasing the reliability of detection. Each cell has a unique address in the monolayer, and can be cloned or monitored in real time during extended time periods, with its growth and functional responses being continuously recorded. Gordeev et al. Biotechnol Bioeng 2011;108:2682–2690.