Abstract
The development of long-term stability microbial formulations is essential for advancing the use of synthetic bacterial communities (SynComs) in agricultural biotechnology. In this study, the shelf-life of a SynCom composed of Bacillus cabrialesii subsp. cabrialesii TE3T, Bacillus paralicheniformis TRQ65, and Priestia megaterium TRQ8 was evaluated. The cofermented SynCom reached a final density of 1.60 × 10⁹ CFU/mL with efficient sporulation (100%). Short-term (30 days) stability assays revealed that trehalose and polyvinylpyrrolidone (PVP) maintained spore viability; however, none of these additives significantly improved stability compared with the additive-free formulation. Thus, long-term (12 months at 23.8 ± 1.7 °C) evaluation showed high stability of the SynCom, which maintained high spore viability, 92%. This finding can be supported since the genomes of these bacteria revealed conserved mechanisms for oxidative and osmotic stress tolerance, including antioxidant enzymes, compatible solute transporters, and PHB biosynthesis. These intrinsic stress-response traits likely contribute to the extended shelf-life of the cofermented SynCom. Overall, this SynCom represents a promising strategy for developing liquid microbial formulations with long stability under ambient conditions.
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