ACID METABOLISM An extended acid panel analysis was performed after 9 and 19 days of growth to identify acids consumed and produced by Tatumella ptyseos (Figure 7) growing in Chardonnay juice. Analyte Chardonnay Juice Pre-Inoculated Day 9 PostInoculation Day 19 PostInoculation TA 4.8 g/L 4.5 g/L 5.8 g/L pH 3.37 3.33 3.19 Acetic Acid <0.05 g/L <0.05 g/L <0.05 g/L Glucuronic Acid <0.10 g/L <0.10 g/L <0.10 g/L Gluconic Acid 0.16 g/L 8.24 g/L 15.92 g/L Malic Acid 2.63 g/L <0.10 g/L <0.10 g/L Citric Acid 0.29 g/L 0.20 g/L 0.23 g/L Lactic Acid 0.11 g/L 1.20 g/L 0.84 g/L Succinic Acid <0.20 g/L <0.20 g/L <0.20 g/L Tartaric Acid 4.51 g/L 4.16 g/L 4.49 g/L Glucose+Fructose 235 g/L 238 g/L 230 g/L Figure 7: Juice Acid Analysis CONCLUSIONS We have verified that Tatumella ptyseos strains isolated from Napa Valley grape juice samples are capable of growth in white grape juice. The 4.5 g/L of malic acid present in the juice was consumed in 72 hours at room temperature. Lactic acid production appears to occur during malic acid degradation, followed by a decrease after the observed initial increase. There was no indication of acetic acid production during the course of the experiment. Tatumella ptyseos growth resulted in an initial decrease in acidity after Malic acid was consumed followed by an increase in acidity as high levels of Gluconic acid were produced during prolonged growth. Elevated temperatures result in extremely rapid cell growth rates allowing populations to reach >10,000,000 cells/mL in under 24 hours. Growth is reduced or halted at lower temperatures typically used during the cold soak process. We determined that T. ptyseos was extremely sensitive to SO2. Even small amounts of added SO2 prevented initial Tatumella growth and provided lasting protection. Adequate SO2 additions when crushing grapes would be the most effective means of preventing malic acid degradation by Tatumella ptyseos. REFERENCES Maccario et al. 2024 “Tatumella ptyseos’ Role in Early Degradation of Malic Acid in Grape Juice”, ASEV Technical abstracts 2024, pg. 114 Bubeck et al., 2020, “Bacterial microbiota diversity and composition in red and white wines correlate with plant‑derived DNA contributions and botrytis infection”, Scientific Reports, 10:13828 Kordowska-Wiater et al., 2022, “A Metagenetic Insight into Microbial Diversity of Spontaneously Fermented Polish Red Wines and an Analysis of Selected Physicochemical Properties”, Appl. Sci., 12, 4373 Escribano-Viana et al., 2018, “Impact of Chemical and Biological Fungicides Applied to Grapevine on Grape Biofilm, Must, and Wine Microbial Diversity”, Frontiers in Microbiology, February 2018, 9 36