Two　strains　of　Bacillus　subtilis　designated　YY-10　and　BY-2,　were　isolated　from　the　surface　of　tobacco　and　found　to　be　capable　of　significant　lignin　degradation.　The　predominant　lignin-degrading　enzymes　produced　by　these　strains　were　lignin　peroxidase　(LiP)　and　manganese　peroxidase　(MnP),　respectively.　A　notable　distinction　was　observed　in　the　organoleptic　evaluation　and　volatile　flavor　compounds,　as　determined　by　sensory　evaluation　and　GC–MS　analysis.　The　content　of　volatile　flavor　compounds,　such　as　geranylacetone,　meglumine　trienone　B,　and　meglumine　trienone　C,　was　found　to　be　significantly　increased　in　roasted　tobacco　treated　with　YY-10.　This　treatment　has　been　shown　to　reduce　the　astringent　flavor　of　the　roasted　tobacco　and　improve　the　aroma,　which　in　turn　could　improve　the　quality　of　the　roasted　tobacco.　Conversely,　the　quality　and　aroma　levels　of　the　roasted　tobacco　treated　with　the　crude　enzyme　solution　of　the　BY-2　strain　were　reduced.　Transcriptome　analysis　revealed　that　the　expression　of　genes　related　to　amino　acid　metabolism,　genetic　material　biosynthesis,　and　protein　synthesis　was　up-regulated　in　the　YY-10　strain　compared　with　the　BY-2　strain,　which　promoted　the　biosynthesis　of　LiP.　This　study　provides　a　preliminary　elucidation　of　the　potential　mechanism　by　which　YY-10　enhances　the　quality　of　tobacco　leaves　through　lignin-degrading　enzyme　production,　thus　establishing　a　research　foundation　for　the　subsequent　treatment　of　waste　tobacco　raw　materials　and　industrial　applications.　Copyright　©　2025　Wang,　Long,　Jiang,　Mu,　Su,　Ni,　Ji,　Wang,　Zhou,　Zhan,　Nie,　Li,　Hu,　He　and　Zhang.