High Throughput Viability Assay for Microbiology

Abstract

Counting viable cells is a universal practice in microbiology. The colony forming unit (CFU) assay has remained the gold standard to measure viability across disciplines; however, it is time-intensive and resource-consuming. Herein, we describe the Geometric Viability Assay (GVA) that replicates CFU measurements over 6-orders of magnitude while reducing over 10-fold the time and consumables. GVA computes a sample's viable cell count based on the distribution of embedded colonies growing inside a pipette tip. GVA is compatible with gram-positive and -negative planktonic bacteria, biofilms, and yeast. Laborious CFU experiments such as checkerboard assays, treatment time-courses, and drug screens against slow-growing cells are simplified by GVA. We therefore screened a drug library against exponential and stationary phase E. coli leading to the discovery of the ROS-mediated, bactericidal mechanism of diphenyliodonium. The ease and low cost of GVA evinces it can accelerate existing viability assays and enable measurements at previously impractical scales.

μMET: A Novel Reusable Microfluidic Chip for Precision Microbial Enumeration Tests

“…For instance, recent advances in geometric viability assays within pipette tips provide a quick and cost-effective method for counting live bacterial cells. 14 The Soleris system measures bioburden by detecting changes in color or fluorescence as microbes metabolize nutrients, 15 offering a more rapid and sensitive alternative to traditional colony count methods. However, its reliance on microbial growth can result in the oversight of nonculturable organisms or those with unique growth requirements.…”