Survival and Behavior of Potential Emerging Foodborne Pathogen Streptococcus gallolyticus subsp. gallolyticus During Manufacturing and Shelf Life of Kashar Cheese
Food Science and Nutrition, cilt.14, sa.7, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 14 Sayı: 7
- Basım Tarihi: 2026
- Doi Numarası: 10.1002/fsn3.72131
- Dergi Adı: Food Science and Nutrition
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Food Science & Technology Abstracts, Greenfile, Academic Search Ultimate (EBSCO), Natural Science Collection (ProQuest), Health Research Premium Collection (ProQuest)
- Anahtar Kelimeler: cooked-curd, food safety, Kashar Cheese, MALDI-TOF-MS, physicochemical analysis, Streptococcus gallolyticus subsp. gallolyticus, zoonotic foodborne pathogens
- Bursa Uludağ Üniversitesi Adresli: Evet
Özet
Members of the Streptococcus bovis/Streptococcus equinus complex (SBSEC), frequently detected in the microbiota of artisanal cheeses and as commensals in the gastrointestinal tracts of humans and animals, have raised concerns regarding their potential pathogenicity and the role of foodstuffs in transmission. Streptococcus gallolyticus subsp. gallolyticus (Sgg), associated with endocarditis and colorectal cancer, is a key member of this complex. This study aimed to investigate the survival and behavior of Sgg during the production and shelf life of Kashar Cheese. In sterilized milk used as a baseline growth model, Sgg exhibited biphasic growth, reaching levels above 11 log10 cfu/mL. Isolates were not able to survive in simulated gastric acidity conditions. The survival and behavior of Sgg during processing and storage of Kashar Cheese (a curd scalded Turkish Cheese) inoculated with Sgg at concentrations of 106–108 cfu/mL were monitored using traditional culturing, MALDI-TOF-MS and PCR analysis. Bacterial dynamics were tracked at sequential sampling times representing critical manufacturing and ripening stages: (a) time of inoculation, (b) before curd shearing, (c) curd before scalding, (d) after scalding, and throughout storage on days (e) 1, (f) 7, (g) 15, and (h) 30. Fermentative acidification by using yogurt cultures was more effective in reducing Sgg counts by day 30 of storage compared to lactic acid acidification, with mean reductions of 4.1 log10 and 1.0 log10, respectively; however, no statistically significant differences were observed among the groups (p > 0.05). The scalding step at 75°C for 5 min reduced the bacterial load substantially (3.3–4.1 log10), but did not achieve complete elimination. By day 30, Sgg remained detectable in cheeses produced with lactic acid (7.31 and 2.20 log10 cfu/g) and yogurt cultures (4.11 log10 cfu/g). These results indicate that while fermentative acidification by yogurt cultures provides better control over Sgg than lactic acid acidification, neither the starter cultures nor the 75°C scalding process is sufficient to completely eliminate this pathogen. Consequently, Sgg can successfully withstand traditional manufacturing and thermal hurdles, providing the first evidence of its survival within a cheese matrix during the ripening period. These findings highlight that artisanal or industrial curd-scalded dairy products could serve as a potential vehicle for foodborne transmission of this pathogen, posing a genuine risk to public health. The survival of Sgg during Kashar Cheese production and storage was characterized. These findings highlight the potential for food-chain transmission of Sgg. The results offer critical data to support improved food safety control measures.