To date the effectiveness of antibiotics is undermined by microbial resistance, threatening public health worldwide. The possible failure of conventional antibiotics engenders the need for new drugs, with demanding investments of money, labor and time. Enhancing the efficacy of the current antibiotic arsenal is an alternative strategy. The administration of antimicrobials encapsulated in nanocarriers, such as liposomes, is considered a viable option, though with some drawbacks related to limited affinity between conventional liposomes and bacterial membranes.Here we propose a novel "top-down" procedure to prepare unconventional liposomes from the membranes of prokaryotes (PD-liposomes). These vectors, being obtained from bacteria with limited growth requirements, also represent lowcost systems for scalable biotechnology production. In depth physico-chemical characterization, carried out with dynamic light scattering (DLS) and Small Angle Xray Scattering (SAXS), indicated that PD-liposomes were may be suitable for the employment as antibiotic vectors. Specifically, DLS showed that the mean diameter of loaded liposomes was ~ 200-300 nm, while SAXS showed that the structure was similar to conventional liposomes, thus allowing a direct comparison with more standard liposomal formulations.Compared to free penicillin G, PD-liposomes loaded with penicillin G showed minimal inhibitory concentrations against E. coli that were up to 16-times lower.Noteworthy, the extent of the bacterial growth inhibition was found to depend on the microorganisms from which liposomes were derived. 216 words. Now 198, limit is 200