Production of Enterocins L50A, L50B, and IT, a New Enterocin, by Enterococcus faecium IT62, a Strain Isolated from Italian Ryegrass in Japan

Abstract

Enterococcus faecium IT62, isolated from ryegrass in Japan, was shown to produce three different bacteriocins, two of which had molecular masses and amino acid sequences that corresponded to those of enterocin L50A and enterocin L50B. These peptides existed, however, as chemically modified forms that were either N formylated or N formylated and oxidized at Met 24 . The third bacteriocin, named enterocin IT, had a molecular mass of 6,390 Da, was made up of 54 amino acids, and did not correspond to any known bacteriocin. However, enterocin IT was identical to the C-terminal part of the 16-amino-acid-longer bacteriocin 32 (T. Inoue, H. Tomita, and Y. Ike, Antimicrob. Agents Chemother., 50:1202-1212, 2006). For the first time, the antimicrobial activity spectra for enterocins L50A and L50B were determined separately and included a wide range of gram-positive bacteria but also a few gram-negative strains that were weakly sensitive. Slight differences in the activities of enterocins L50A and L50B were observed, as gram-positive bacteria showed an overall higher level of sensitivity to L50A than to L50B, as opposed to gram-negative ones. Conversely, enterocin IT showed a very narrow antimicrobial spectrum that was limited to E. faecium strains, one strain of Bacillus subtilis, and one strain of Lactococcus lactis. This study showed that E. faecium IT62, a grass-borne strain, produces bacteriocins with very different activity features and structures that may be found in strains associated with food or those of clinical origin, which demonstrates that a particular enterocin structure may be widespread and not related to the producer's origin.

Characterization and identification of weissellicin Y and weissellicin M, novel bacteriocins produced by Weissella hellenica QU 13

“…Some previous studies have reported about multiplebacteriocin-producing LAB such as Lactobacillus (Vaughan et al 2003), Enterococcus (Cintas et al 1998;Izquierdo et al 2008) and Leuconostoc (Papathanasopoulos et al …”

“…Most LAB bacteriocins were synthesized as prepeptides containing N-terminal extension or leader sequences, while some class II bacteriocins have been reported to be synthesized without a leader sequence. The latter includes mutacin BHT-B (Hyink et al 2005), lacticin Q (Fujita et al 2007), lacticin Z (Iwatani et al 2007), enterocin Q (Cintas et al 2000) and enterocin L50 (Cintas et al 1998;Criado et al 2006a;Izquierdo et al 2008), most of which are class IId bacteriocins.…”

Development of Bacteriocinogenic Strains of Saccharomyces cerevisiae Heterologously Expressing and Secreting the Leaderless Enterocin L50 Peptides L50A and L50B from Enterococcus faecium L50

“…In this respect, it has been reported that Met in bacteriocins become spontaneously oxidized, especially during their purification to homogeneity, leading to a loss or reduction of their antimicrobial activities (5,10,29). Moreover, a study carried out simultaneously with the one described herein reported the spontaneous chemical modification of EntL50A and EntL50B during their purification due to Met 1 formylation and Met 24 oxidation to MetSO, rendering active and inactive peptides, respectively (27). Considering that beer production includes a wort aeration step to promote brewing yeast growth and enhance the start-up of fermentation (47), the oxidative partial inactivation of EntL50A and EntL50B may hamper their application as beer biopreservatives at this stage of the brewing process.…”

Enterocin 96, a Novel Class II Bacteriocin Produced by Enterococcus faecalis WHE 96, Isolated from Munster Cheese

“…The growth of indicator strains was monitored at 600 nm for 24 h at 37°C. Bacteriocin activity was expressed as the maximal difference in absorbance between controls and assays, which was reached at the end of the exponentialgrowth phase (between 7 and 10 h depending on the strain) (9).…”