[4S02a] 03. Fermentation Physiology/ Technology - Part 2

3:00 PM - 3:20 PM JST(6:00 AM - 6:20 AM UTC)

[4Ferm-07] GABA and Polyamine Production in Mold-Fermented Cheese Driven by Penicillium camemberti and Microbial Interactions

○Yuri Ishii¹, Nonno Ogawa², Shinsuke Fujiwara^1,2 (1. Sch. Biol. Environ. Sci., Kwansei Gakuin Univ. (Japan), 2. Grad. Sch. Sci. Technol., Kwansei Gakuin Univ. (Japan))

Keywords:

polyamine,GABA,mold-fermented cheese,mass spectrometry imaging

Polyamines (putrescine [Put] and spermidine [Spd]) and γ-aminobutyric acid (GABA) are bioactive metabolites enriched in fermented foods. In mold-fermented cheese (MFC), lactic acid bacteria (LAB) acidify milk, while Penicillium camemberti forms a surface mycelial layer during ripening. However, the mechanism underlying metabolite accumulation and its spatial relationship to microbial growth remain unclear. Here, we investigated the contribution of P. camemberti to polyamine-related metabolites and their spatial distribution during MFC ripening. Laboratory-scale cheeses were prepared using Lactococcus lactis and P. camemberti. Put and Spd were detected exclusively in P. camemberti-inoculated cheeses, consistent with the absence of canonical polyamine biosynthetic pathways in L. lactis MG1363. Ripening temperature influenced metabolite profiles: Put increased at 15°C relative to 10°C, and Spd was detected only at 15°C, whereas GABA was higher at 10°C than at 15°C. Mass spectrometry imaging (MSI) also revealed that polyamine-related metabolites were enriched at the cheese surface and extended into the mycelial layer. In contrast, cheeses without P. camemberti showed no detectable polyamine-related signals, except for weak ornithine (Orn) signals at 15°C. These results support a primary role of P. camemberti in polyamine-related metabolite production and localization in MFC. During ripening, P. camemberti-inoculated cheeses exhibited a pH shift from ~4.5 to 7–8. However, when the fungus was cultivated on LAB-free milk agar adjusted to pH 4.0–6.0, polyamines were not detected, although GABA was consistently produced, indicating that acidity alone is insufficient to induce polyamine synthesis. Supplementation experiments showed that arginine (Arg) addition induced Spd and GABA localization within the mycelial layer, whereas Spd was absent without Arg. Excess Orn also enabled Spd detection. These findings indicate that polyamine production in MFC arises from fungal metabolism supported by precursor supply from LAB. Although GABA is typically synthesized from glutamate via glutamate decarboxylase, our supplementation experiments indicate that polyamine metabolism contributes substantially to GABA accumulation in mold-fermented cheese, highlighting cooperative metabolism during ripening.