Identification and Analysis of Preservation Conditions for Soil-Isolated Priestia megaterium Subspecies

This study aimed to isolate and identify a subspecies of Priestia megaterium with potential probiotic properties from soil and evaluate its cryopreservation conditions. The bacterium was isolated using dilution and plate spreading methods, and identified through 16S rDNA sequencing and physiological and biochemical experiments. Different cryoprotectants (glycerol, DMSO, and starch) were also assessed. The results showed that the strain is a Gram-positive spore-forming bacterium, with 8% DMSO providing the best protective effect, glycerol showing a relatively poor effect, and starch having a detrimental impact. This study provides a theoretical basis for the development and application of probiotics.