January 28, 2025 - Katerina Roth, Ph.D. Candidate (Snyder Lab), Cornell University

Department of Food Science, Cornell University


Speaker Bio
Katerina received a bachelor’s degree in food science at UC Davis before working at a food analysis company near San Jose. She matriculated to Abby Snyder’s lab at Cornell in 2020. She was named as a James Beard Foundation National Scholar in 2022 and was granted a USDA NIFA predoctoral Fellowship in 2023. She works on an ISO working group for standardization of the detection of Alicyclobacillus spp. and interns at the Cornell Center for Technology Licensing. An avid proponent of outreach, Katerina was the conference chair of ComSciCon-NY and has served as a mentor of Cornell’s Multicultural Academic Council. Additionally, she served as Chair of the Food Science department’s Community Outreach Committee and is Vice President of Biodiversify at Cornell.

Food spoilage is a major issue leading to waste, lost revenue, and consumer dissatisfaction. Beverages are known to be spoiled by Alicyclobacillus spp., which are extremophilic sporeformers that cannot be killed by traditional pasteurization methods. The spoilage metabolite guaiacol is only produced by a subset of Alicyclobacillus spp. under specific beverage storage conditions, making precise assessment of spoilage risk a priority for beverage and ingredient producers. In the first study, whole genome sequencing and an ANIb cutoff of 95% was used to establish three new species of Alicyclobacillus. One of these, A. suci, was shown to be a guaiacol producer highly related to A. acidoterrestris. The purpose of the next study was to compare a RT-PCR-based method, the GENE-UP® PRO ACB assay, to the IFU Method No. 12 Enumeration and Enrichment methods. The new assay evaluated spoilage risk in addition to offering a faster turnaround time. Ten species of Alicyclobacillus were detected using the tested RT-PCR assay, while A. dauci and A. kakegewensis were not detected using either IFU protocol. Low concentrations (1-10, 10-100, and 100-1,000 CFU/10 ml) of A. acidoterrestris, A. suci, and A. acidocaldarius were tested in five matrices. The proportion of positive samples identified using the tested RT-PCR assay (62/84) or the IFU Enrichment protocol (62/84) did not differ significantly from the proportion of inoculated samples (63/84). However, the IFU Enumeration method (32/84) detected statistically fewer positives. This study showed consistent detection of Alicyclobacillus spp. using either the IFU Enrichment protocol or the tested RT-PCR assay, which both outperformed the IFU Enumeration protocol. The aim of the next study was to uncover genomic determinants of guaiacol production across the genus. Using a genome-wide association study, several of the genes significantly enriched in guaiacol-producing Alicyclobacillus spp. were found to be associated with oxidative stress response, including vdcC, a phenolic acid decarboxylase putatively responsible for guaiacol synthesis. When looking at guaiacol production using a peroxidase colorimetric assay, we found that strains of A. suci (63.0±14.2 ppm) produced significantly (p<0.01) more guaiacol on average in media than did strains of A. acidoterrestris (25.2±7.0 ppm).