UV-Induced Spectral and Morphological Changes in Bacterial Spores for Inactivation Assessment

Area of Science:

• Microbiology
• Spectroscopy
• Bacterial spore inactivation

Background:

• Spore-forming bacteria pose risks in industrial, healthcare, and defense sectors.
• Effective spore inactivation requires robust detection and validation methods.
• UV radiation is a common inactivation method, but its effects on spore characteristics are not fully understood.

Purpose of the Study:

• To investigate spectral and morphological changes in Bacillus thuringiensis spores following UV exposure.
• To identify spectroscopic indicators for assessing spore viability post-inactivation.
• To improve spore decontamination and validation assay designs.

Main Methods:

• Absorbance and fluorescence spectroscopy to analyze spectral intensity changes.
• Micro-Raman spectroscopy to detect DPA release and protein degradation.
• Electron microscopy and light scattering to observe morphological alterations.

Main Results:

• Observed exponential decay in spectral intensity of amino acids and proteins with UV exposure.
• Noted a logistic increase in dimerized DPA and release of DPA.
• Documented spore body shriveling, core content leakage, and disruption of outer layers.

Conclusions:

• UV exposure induces significant spectral and morphological changes in bacterial spores.
• Spectroscopic indicators were identified for determining spore viability after UV treatment.
• Findings support the development of improved spore decontamination and validation protocols.