Stability of spore-based biosensing systems under extreme conditions

The full exploitation of bacterial whole-cell biosensing systems in field applications requires the survival of bacterial cells and long-term preservation of their sensing ability during transportation and on-site storage of such analytical systems. Specifically, there is a need for rapid, simple and inexpensive biosensing systems for monitoring human health and the environment in remote areas as well as developing countries, which often suffer from harsh atmospheric conditions and inadequate commercial distribution and storage facilities. Our laboratory has previously reported the successful use of bacterial spores as vehicles for the long-term preservation and storage of whole-cell biosensing systems at room temperature. In the present research, we have accomplished a year-long study to investigate the effect of extreme climatic conditions on the stability of spores-based whole-cell biosensing systems. The spores were stored in laboratory conditions that simulated those found in real harsh environments, including, extreme temperatures and humidity levels, and desiccation. This study was crucial in determining the germination ability and analytical performance of the spore-based sensing systems upon storage in such conditions in order to support their effective use in the field, in extreme environments. Our results proved that the intrinsic resistance of spores to harsh environmental conditions helped maintain the integrity of the encapsulated sensor bacteria. The revived active cells actually retained their analytical performance during the course of the 12-month storage study. We envision that spore-based sensing systems could pave the way to the use of whole-cell biosensors in field applications and in areas where they have not been employed so far.