Multiple Factors Contribute to Guaiacol Production by Alicyclobacillus acidoterrestris and Alicyclobacillus suci in Apple Juice, as revealed by Transcriptomic and Phenotypic Analyses

Alicyclobacillus acidoterrestris and Alicyclobacillus suci are both guaiacol producers that can cause spoilage in products like juices. To study the genetic underpinnings of guaiacol production, transcriptomics was performed on multiple strains of A. suci and A. acidoterrestris under guaiacol production conditions in apple juice. While guaiacol production was consistently higher by A. acidoterrestris than by A. suci, the gene expression levels associated with guaiacol production (e.g., vdcC, vdcB, vdcD) showed significant variability across strains of both species, suggesting that other factors beyond vdcC transcription influence the amount of guaiacol produced. This research provides insights for beverage producers in assessing spoilage risks and developing more informed mitigation strategies. Overall design: six strains were grown overnight before being inoculated into 50 mL of apple juice at a final concentration of approximately 104 CFU/mL. The Simply Apple brand juice was purchased from a local supermarket. The samples were incubated at 30°C and sampled on day 3