Silk as a Means of Recovering Bacteriocin From a Culture Medium

Abstract

Bacteriocins are thermostable molecules of a proteinaceous nature produced by different microorganisms, such as lactic acid bacteria (LAB), with an inhibitory action spectrum directed toward related strains (1–3). However, different Enterococcus faecium strains are bacteriocin producers, and their activity spectra are not only directed toward related microorganisms (4). Within the last decade, biopreservation has received increased attention as a new method to control pathogenic and spoilage bacteria in foods, and this trend includes the use of bacteriocin-producing LAB or addition of their bacteriocins. For this reason, techniques to purify and concentrate these molecules have become very important, but few assays have been published (5,6). A simple procedure is proposed here that can easily be carried out in the laboratory. Silk, produced by Bombix mori L., is made up of two different proteins: sericin and fibroin; the first is heat labile, while the second is very resistant to heat and acid or alkaline media. Silk has the property of catching and interacting with proteins, and it has been employed to immobilize enzymes (7). Because of this characteristic, silk could be considered as a new alternative to recover, concentrate, and purify bacteriocin out of a culture medium, since the interaction between silk and bacteriocin can be reversible (8).