Purification and characterization of macrolactins and amicoumacins from Bacillus licheniformis BFP011: a new source of food antimicrobial substances

Abstract

In this study, Bacillus licheniformis BFP011 has been cultivated for producing antimicrobial compounds, which were concentrated from the crude supernatant and purified using thin-layer chromatography. The antimicrobial activity was investigated in the presence of several organic solvents and detergents, and inhibiting effects to various Gram-negative and Gram-positive human pathogenic and food spoilage bacteria were observed. Three bands (F4, F5 and F6) showing antimicrobial activity against Salmonella typhi ATCC 5784 were subjected to reversed-phase high-performance liquid chromatography purification. Two peaks of fraction F5, F5-P3 and F5-P4, showed 100% inhibition against S. typhi ATCC 5784. The contained mixture of antimicrobial compounds consists of macrolactins and amicoumacins, which induced the collapse and breaking of S. typhi ATCC 5784 cell membranes in a time-dependent manner. Taken collectively, the results indicate that these compounds may represent promising candidates for the development of food preservative agents of natural origin, as well as novel antimicrobial drug candidates against multiresistant bacterial strains. RESUMENEn el presente estudio, se cultivo Bacillus licheniformis BFP011 para producir compuestos antimicrobianos; estos fueron concentrados del sobrenadante crudo y purificado empleando cromatografia en capa fina (CCF). En presencia de varios solventes y detergentes organicos se analizo la actividad antimicrobiana, observandose, ademas, los efectos inhibidores de varias bacterias gram-negativas y gram-positivas, patogenas para los seres humanos y causantes del deterioro de los alimentos. Mediante RP-HPLC se purificaron tres franjas (F4, F5 y F6) que mostraron actividad antimicrobiana contra la Salmonella typhi ATCC 5784, comprobandose que los dos picos de la fraccion F5 (F5-P3 y F5-P4) provocan una inhibicion del 100% contra la S. typhi ATCC 5784. La mezcla de compuestos antimicrobianos contiene macrolactinas y amicoumacinas; estas produjeron el colapso y el rompimiento de las membranas celulares de S. typhi ATCC 5784 a medida que fue transcurriendo el tiempo. Considerados en su conjunto, estos resultados indican que es posible que dichos compuestos sean sustancias prometedoras para la creacion de agentes conservantes de alimentos de origen natural, y para el desarrollo de medicamentos antimicrobianas novedosas contra cepas bacterianas multirresistentes.