Alkaline glutaraldehyde (GTA) has been used as a high level chemical disinfectant and sterilant for many years and is known to kill a broad spectrum of organisms ranging from vegetative eukaryotes to bacterial endospores. Although the mechanism of sporicidal action has been studied on numerous occasions, GTA's exact mechanism(s) of action are still debated. In addition to the uncertainty of GTA's mechanism(s) of action, GTA has also shown significant variability in the time required to kill endospores and naked viruses. A better knowledge of the lethal mechanism(s) of GTA is needed to understand this discrepancy in kill times for GTA against spores of different species. Similar trends have been observed in GTA's activity against non-enveloped viruses. Based on previous work, one proposed major mechanism of GTA's sporicidal activity is related to the number of available primary amines located on the surface of microbes. In this study, we have compared the efficacy of GTA on spores from 5 Bacillus species. We have also developed a method for staining these spores with amine reactive dyes to create fluorescent profiles correlating to the abundance of free amino groups on each spore type. We also describe a method for staining non-enveloped viruses to identify exposed primary amino groups on capsid proteins that may act as targets for GTA, using amine reactive Gold nanoparticles. We found that GTA 6-Log10 reduction times for various spore types varied at both the batch and species level. Spore coat thickness and fluorescence were useful tools in predicting the susceptibility of spores to GTA. Amine reactive gold particles (AuNPs) also proved useful in identifying virus susceptibility to GTA. Ultimately, more reliable disinfection testing methods are needed, and caution should be used when trying to extrapolate data generated from surrogate organisms to other species.



College and Department

Life Sciences; Microbiology and Molecular Biology



Date Submitted


Document Type





endospore, glutaraldehyde, Alexa Fluor, poliovirus, human papilloma virus



Included in

Microbiology Commons