Akademik Veri Yönetim Sistemi
Journal of Food Safety, cilt.46, sa.3, 2026 (SCI-Expanded, Scopus)
Thermophilic and thermotolerant spore-forming bacilli that survive pasteurization may persist in dairy systems through biofilm formation. In this study, thermophilic isolates recovered from commercially marketed pasteurized milk in Ankara, Türkiye, were characterized phylogenetically and evaluated for temperature- and surface-dependent biofilm formation. Eight isolates were obtained from eight milk samples after selective enrichment at 55°C. Based on 16S rRNA gene analysis and phylogenetic reconstruction, the isolates were distributed into two lineages: one Aeribacillus-affiliated isolate (A1; closest BLAST match to Aeribacillus pallidus, 96.74% identity) and seven Bacillus isolates, with closest BLAST identities ranging from 88.83% to 98.42%. Among the latter, D2 showed the highest similarity to Bacillus licheniformis (98.42%) and clustered near the B. licheniformis reference clade, supported by a 91% bootstrap value. On Congo red agar, increasing the temperature from 45°C to 60°C induced transitions from smooth colonies to wrinkled, intensely pigmented morphotypes, indicating enhanced matrix-associated phenotypes. Pellicle formation at 60°C was restricted to 3 of 8 isolates (A1, C2, and D2). On polystyrene, most isolates produced maximal biofilm biomass at 45°C–50°C, whereas on stainless steel, several isolates maintained high viable biofilm populations up to 55°C. In milk-based adhesion assays on eight abiotic materials, Aeribacillus sp. A1 showed the strongest attachment to polystyrene, whereas Bacillus sp. C2 exhibited the highest colonization on stainless steel. These findings identify 45°C–55°C as a critical thermal window that promotes biofilm persistence by thermophilic spore-formers in dairy environments.