NIST only participates in the February and August reviews.
Quantifying microbial cells is challenging since microbes vary in size, shape (rod, sphere, etc.) and morphology (single cells, doublets, chains, clusters, etc.), and typically average more than one genome copy per cell. Additionally, microbial samples encompass an enormous range of complexity depending on the number of different microbes, acellular environmental particulates, and sample preparation or preservation. We are establishing standards, measurement methods, and RMs to enable stakeholders to assess performance and comparability across measurements and products (1-4).
For decades, CFU (colony forming unit) assays have been the definitive measurement for the viability of a microbial sample and have been written into regulations and technical standards including those related to food and pharmaceutical safety, antimicrobial susceptibility, and water quality. Yet, CFU measurements are imprecise, relatively slow, and difficult to correlate with viable cell count or nucleic acid-based measurements such as metagenomic sequencing. Newer viable cell count methods rely on a range of cell characteristics (e.g., heat generated, ATP production, membrane permeability) and measurement modalities (e.g., calorimetry, plate readers, flow cytometry) to paint a fuller picture of microbial cell health and activity. Modern techniques also enable us to go beyond CFU and measure the total number of cells present, a critical need for truly characterizing a sample. Total or “absolute” microbial cell count is a fundamental measurement of microbial cell populations and facilitates more accurate interpretation of other types of measurements (e.g., viability, genome copy number, genetic sequencing).
Results from this work are anticipated to support stakeholders in a wide range of microbial-related industries and research sectors. Our research group is interdisciplinary, drawing from diverse previous research experiences including wet-lab and computational work. Interested candidates are invited to reach out to discuss potential proposals.
(1) https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2025.1631377/full
(2) https://pubs.acs.org/doi/10.1021/acsomega.5c10969
(3) https://onlinelibrary.wiley.com/doi/10.1002/jbio.202100175
(4) https://www.nist.gov/programs-projects/saccharomyces-cerevisiae-rm-8230-nist-reference-material-supporting-research-and
Microbiology; Cell Count; Quantification; Microbial Communities; Flow Cytometry; Microbiome; Reference Materials; Bioinformatics; Engineering Biology; Viability;
level
Open to Postdoctoral applicants