Nontargeted Lipidomics Reveals Key Membrane Lipids in Three Bifidobacterium animalis Strains with Different Spray Drying Resistance

The cell membrane of lactic acid bacteria (LAB) functions as a crucial barrier against external conditions. Spray drying, a technique used for large-scale bacterial powder production, exposes cells to high temperatures, resulting in membrane damage. In this study, three strains of Bifidobacterium animalis A12, F1-7, and KV9 with significant differences in survival rates after spray drying (47.28 ± 9.00, 11.12 ± 2.62, and 37.44 ± 0.22%, respectively) were selected for analysis. A12 exhibited the strongest SYTO-9 fluorescence intensity, indicating the highest membrane integrity after spray drying. Subsequently, UHPLC-Q-Exactive MS-based lipidomics identified two key lipid species, fatty acyl 18:1; O3 and cardiolipin 15:0_18:0_28:0_22:5, which were potentially crucial for bacterial membrane heat resistance. KEGG pathway analysis further revealed that glycerophospholipid metabolism was the most significantly enriched pathway. This study provides insights into critical membrane lipids that contribute to the heat resistance of B. animalis during spray drying, offering a theoretical reference for screening stress-resistant LAB.