Fourier transform infrared reflectance microspectroscopic studies of bacterial endospores

Fourier transform infrared (FT-IR) microscopy has been applied in the studies of bacterial spores. The differences between untreated spores of Bacillus and Clostridium and those preheated by autoclaving were examined by reflectance microscopy. It was observed that autoclaved spores were differentiable from untreated spores by their mid-infrared vibrational spectral features and chemometrics. FT-IR reflectance microspectroscopy was applied to the classification of bacterial endospores, both with and without heat-treatment. These studies showed that pretreatment by autoclaving enhanced classification of bacterial spore species used in these studies. A detailed study of the extent to which calcium dipicolinate, the divalent salt of dipicolinic acid, contributes to the mid-infrared absorbance of bacterial spores was conducted. This was facilitated by the use of Bacillus subtilis spores genetically engineered to be devoid of this biomarker. Differences between B. subtilis spores grown on different growth media were observed by infrared spectroscopy and multivariate analysis. This was studied to determine if reflectance microscopy could be utilized to distinguish the medium used to grow these microorganisms as a tool to aid in classification. A study was performed to calculate the mid-infrared optical constants of B. subtilis using reflectance microscopy. The information obtained could be utilized in remote sensing applications of these microorganisms. The stability of B. subtilis DNA superheated in water was studied which showed that significant amounts of the DNA survived 120s at 190°C to be detected by real-time polymerase chain reaction. This study showed that reduced detection times may be realized for bacterial spores using the methodology used. A novel system, utilizing a reflective porous alumina sensor, was studied and characterized for its use in infrared reflectance spectroelectrochemical applications, specifically those applications where nanofiltration would be required in turbid systems.