Aroma-producing profiles, degradation mechanism of a β-carotene-degrading Bacillus thuringiensis strain

Food flavor is closely related to the type and content of its flavor compounds. The degradation of β-carotene by microorganisms to produce volatile aroma compounds has shown great potential in enhancing the flavor quality of foods. This study aims to investigate the ability and mechanism of Bacillus thuringiensis 4-1 to degrade β-carotene and to identify key aroma compounds produced during this process. To our knowledge, this is a relatively fast microbial β-carotene degradation reported (>90 % degradation within 3 h at 10 mg/L), outperforming published fungal systems that typically require more than 24 h. During this rapid process, Bacillus thuringiensis 4-1 produced key degradation products with floral, fruity, and woody aromas, such as 6-methyl-5-hepten-2-one, β-cyclocitral, β-ionone, and dihydroactindiolide. Our study further revealed that sodium nitrate induced the strain to produce small molecules, including benzaldehyde, isovaleric acid, isobutyric acid, and acetic acid, which contributed to β-carotene degradation by cleaving its double bonds at various positions. • Bacillus thuringiensis 4-1 degrades over 90 % of β-carotene within 3 h. • Key volatile compounds contribute floral, fruity, and woody aromas during fermentation. • Small molecules such as isovaleric acid mediate the degradation of β-carotene. • Sodium nitrate regulates organic acid production by inducing oxidative stress. • The study provides new insights into microbial β-carotene degradation.