Mode of Action of Disinfection Chemicals on the Bacterial Spore Structure and Their Raman Spectra.

Dmitry Malyshev,Magnus Andersson,Krister Wiklund,Per Ola Andersson,Tobias Dahlberg,Sara Henriksson

doi:10.1021/acs.analchem.0c04519

Dmitry Malyshev, Magnus Andersson + Show 4 more

Open Access

https://doi.org/10.1021/acs.analchem.0c04519

Copy DOI

Journal: Analytical Chemistry	Publication Date: Feb 1, 2021
Citations: 38	License type: cc-by

Affiliation: Umeå University, Uppsala University

Abstract

Contamination of toxic spore-forming bacteria is problematic since spores can survive a plethora of disinfection chemicals and it is hard to rapidly detect if the disinfection chemical has inactivated the spores. Thus, robust decontamination strategies and reliable detection methods to identify dead from viable spores are critical. In this work, we investigate the chemical changes of Bacillus thuringiensis spores treated with sporicidal agents such as chlorine dioxide, peracetic acid, and sodium hypochlorite using laser tweezers Raman spectroscopy. We also image treated spores using SEM and TEM to verify if we can correlate structural changes in the spores with changes to their Raman spectra. We found that over 30 min, chlorine dioxide did not change the Raman spectrum or the spore structure, peracetic acid showed a time-dependent decrease in the characteristic DNA/DPA peaks and ∼20% of the spores were degraded and collapsed, and spores treated with sodium hypochlorite showed an abrupt drop in DNA and DPA peaks within 20 min and some structural damage to the exosporium. Structural changes appeared in spores after 10 min, compared to the inactivation time of the spores, which is less than a minute. We conclude that vibrational spectroscopy provides powerful means to detect changes in spores but it might be problematic to identify if spores are live or dead after a decontamination procedure.

Highlights

A spore is an inactive seed-like form that some bacteria species can take to survive in a hostile environment
To measure the impact of the sporicidal chemicals on the spores’ Raman spectra, we first assessed the vibrational peaks in the absence of chemicals on purified B. thuringiensis spores using laser tweezers Raman spectroscopy (LTRS)
We treated B. thuringiensis spores with common disinfection chemicals, chlorine dioxide, peracetic acid, and sodium hypochlorite, and measured changes in the spore structure and Raman spectra

Summary

■ INTRODUCTION

A spore is an inactive seed-like form that some bacteria species can take to survive in a hostile environment. It inactivates via denaturation of proteins, enzymes, and metabolites by oxidation of sulfhydryl and sulfur bonds.[46] Peracetic acid has been shown to work against spores and it is effective in solution.[47] We first measured the Raman spectrum of peracetic acid itself (Figure 2F) and confirmed that it is consistent with previous studies and that it does not decrease over the measurement time.[48] We treated and investigated spores incubated with 1% peracetic acid This concentration was chosen as the upper end of the reported sporicidal concentrations of peracetic acid.[49] As with sodium hypochlorite, there was a variation in the lag time before DPA loss, ranging from 5 to 18 min.

■ CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES