Baeyer-Villiger monooxygenases (BVMOs) are flavin enzymes activating O2 to oxidise ketones into lactones or esters, and amines or sulfides. Abundant in actinobacteria, they drew attention in mycobacteria when EthA was shown to oxidise ethionamide into an S-oxide blocking mycolic acid (MA) synthesis in M. tuberculosis. Six BVMOs have been identified in the Mtb genome and four characterised by combining bioinformatics, modelling, docking and biochemistry, yet their substrates, roles and structures remain largely unknown. ethA and mymA deletions alter MA profiles and envelope permeability, and MA degradation products suggest oxygen insertion at the beta-keto-mycolic motif, linking BVMOs to cell-wall turnover and survival under starvation. LIMONE will define the structure and function of mycobacterial BVMOs and establish their role in MA degradation, their substrate specificity, functional redundancy and distinct physiological roles, through two complementary objectives in coordinated, synergistic work packages.