Rapid microbial viability assay using scanning electron microscopy: a proof-of-concept using Phosphotungstic acid staining.

Multiple stains have been historically utilized in electron microscopy to provide proper contrast and superior image quality enabling the discovery of ultrastructures. However, use these microbiological viability assessment has limited. Phosphotungstic acid (PTA) staining is a common negative stain used scanning (SEM). Here, we investigate feasibility new SEM-PTA assay, aiming determine both viable dead microbes. The optimal sample preparation was established by bacteria with different PTA concentrations incubation times. Once assay conditions were set, applied protocol various samples, evaluating bacterial under conditions, comparing results culture. five minutes 10% exhibited strong distinction between micro-organisms perceived as hypo-dense, displaying intense internal which confirmed high Tungsten (W) peak on EDX spectra. count after freezing, freeze-drying, or oxygen exposure, concordant To our knowledge, this study first contribution towards live bacteria. strategy demonstrated rapid, cost-effective efficient presenting an open-view sample, providing potentially valuable tool for applications microbiome investigations antimicrobial susceptibility testing.