Detection of Bacillus Subtilis Endopores Using an Online Water Bioburden Analyzer

Bacterial endospores represent a significant challenge to the pharmaceutical industry due to their presence in the environment, resistance to many commonly used inactivation procedures, and difficulty in culturing using traditional plating methods. This may result in the inadvertent release of contaminated products that may present health concerns for the patient. As a result, the use of a bio-fluorescent particle counter (BFPC) may prove advantageous for the detection of both water-borne and air-borne spores as their detection is not dependent on traditional culturing methods. In this study, we investigate the ability of an online water bioburden analyzer (OWBA), a specific class of BFPC, to detect Bacillus subtilis spores in pharmaceutical-grade water and present the results as auto-fluorescence units (AFU's) per B. subtilis spore. The spores were a commercial grade spore preparation and were previously quantified per manufacture recommendations. The results show that the OWBA can detect B. subtilis spores with an accuracy of 1.25 AFU per spore. The limit of detection was determined to be 1 spore/mL with a linearity greater than 0.9025 up to a concentration of 100 spores/mL. This data shows that OWBA's are a rapid and effective tool for the detection of bacterial endospores in pharmaceutical waters.