Development of a technique for determining the viability of dormant organisms in powdered substances

The purposes of pharmaceutical biotechnology and quality control of probiotics containing lyophilized bacterial preparations, as well as the purpose of ensuring biological safety, require methods for rapid determination of the viability of dormant forms. This paper describes an approach to determining the viability of dry powdered substances. Lyophilized powder of Kalanchoe daigermontiana, dry dormant eggs of Artemia salina, and dry powder of Lycopodium sp. spores were proposed as model objects. Suspensions of virus-like particles (VLPs) to SARS-CoV-2 were proposed as a cell-free reference material. The following methods of elemental analysis were used in the study: X-ray fluorescence spectroscopy (XRF) on an energy-dispersive device, atomic absorption spectroscopy with electrothermal atomization, and Zeeman background correction (GZ-AAS). The free water content was determined by NMR spin echo. A new method was also used for recording the kinetics of changes in broadband radio emission in the centimeter and millimeter wavelength ranges, with a measurement duration of up to 20 minutes. Live and inactivated powdered preparations of K. daigermontiana and A. salina were prepared and characterized by elemental composition, water content, and spin-spin relaxation time (T2). For these live and inactivated preparations, it was determined that the flux density of intrinsic thermal radio emission decreases by an order of magnitude with the loss of viability. In the future, the results obtained will allow for a rapid test of the viability of lyophilized therapeutics (from medicinal plants to bacterial mixtures that stabilize the intestinal microflora). Keywords: millimeter emission, X-ray fluorescence analysis, NMR spin echo, nanoparticles, powdered substances, medicinal plant raw materials