produces more guaiacol in media and has duplicate copies of compared to closely related .

Unlabelled: Some species of the genus cause spoilage in juices and other beverages due to the production of guaiacol, a phenolic compound, and off-aroma. However, little is known about the genomic determinants of guaiacol production across the genus. In this study, we found that several of the genes significantly enriched in guaiacol-producing spp. are associated with oxidative stress response, including , a phenolic acid decarboxylase putatively responsible for guaiacol synthesis. The food industry recognizes as the primary guaiacol-producing species found in beverages, though that species was recently split into two closely related yet genetically distinct species, and . We found that strains of (63.0 ± 14.2 ppm) produced significantly ( < 0.01) more guaiacol on average in media than did strains of (25.2 ± 7.0 ppm). Additionally, and genomes each had duplicate copies of , while only a single copy of was found in the genomes of and . Although the food industry has not historically differentiated between and it may be increasingly important to target the species with greater spoilage potential. Therefore, we also demonstrated that sequencing a single locus, such as the full-length 16S region or is sufficient to differentiate between and .

Importance: Microbial spoilage increases food waste. To address that challenge, it is critical to recognize and control those microbial groups with the greatest spoilage potential. Non-specific targeting of broad microbial groups (e.g., the genus of ) in which only some members cause food spoilage results in untenable, overly broad interventions. Much of the food industry does not differentiate between guaiacol-producing and non-guaiacol-producing species. This is overly broad because spp. which cannot produce guaiacol can be present in beverages without causing spoilage. Furthermore, no distinction is made between and because is newly split from and most of the food industry still considers them to be the same. However, these findings indicate that may have greater spoilage potential than due to differences in their genomic determinants for guaiacol production.