Isolation and Characterization of Enterocin SE-K4 Produced by Thermophilic Enterococci, Enterococcus faecalis K-4

Abstract

Enterococcus sp. K-4, with a bacteriocin-like activity against E. faecium, was isolated from grass silage in Thailand. Morphological, physiological, and phylogenetic studies clearly identified strain K-4 as a strain of E. faecalis. Strain K-4 produced a maximal amount of bacteriocin at 43-45 degrees C. We purified, for the first time, the bacteriocin produced at high temperature by E. faecalis to homogeneity, using adsorption on cells of the producer strain and reversed-phase liquid chromatography. The bacteriocin, designated enterocin SE-K4, is a peptide of about 5 kDa as measured by SDS-PAGE, and Mass spectrometry analysis found the molecular mass of 5356.2, which is in good agreement. The amino acid sequencing of the N-terminal end of enterocin SE-K4 showed apparent sequence similarity to class IIa bacteriocins. Enterocin SE-K4 was active against E. faecium, E. faecalis, Bacillus subtilis, Clostridium beijerinckii, and Listeria monocytogenes. Enterocin SE-K4 is very heat stable.

Silage and Microbial Performance, Old Story but New Problems

“…Moreover, enterocin SE-K4, which was a bacteriocin produced by a thermophilic strain Ec. faecalis K-4 isolated from a silage produced in Thailand, was characterized and its production was coded on a 37 Kb plasmid 2,4 . This genetic information coded on plasmids will be useful for the improvement of LAB inoculants.…”

Biochemical and Genetic Characterization of Mundticin KS, an Antilisterial Peptide Produced by Enterococcus mundtii NFRI 7393

“…Several subgroups have been defined within class II, notably the class IIa bacteriocins, which contain a consensus YGNGV amino acid motif near the N terminus and are active against the food-borne pathogen Listeria monocytogenes (8,22). Class IIa bacteriocins are widespread among LAB and include pediocins AcH and PA-1 produced by Pediococcus acidilactici (3,24), piscicolin 126 produced by Carnobacterium piscicola (19), sakacin P and 674 produced by Lactobacillus sakei (16,36), enterocin SE-K4 produced by Enterococcus faecalis (7), and leucosin A produced by Leuconostoc gelidum (13).…”

“…We previously did a survey of LAB from fermented tropical vegetables and silage in Thailand to search for bacteriocin producers (7) and successfully isolated several thermophilic enterococcal strains that produced bacteriocins against Enterococcus faecium. Enterocin SE-K4, belonging to class IIa bacteriocins, produced by one such thermophilic enterococcus, Enterococcus faecalis K-4, has previously been isolated and characterized (7).…”

“…Enterocin SE-K4, belonging to class IIa bacteriocins, produced by one such thermophilic enterococcus, Enterococcus faecalis K-4, has previously been isolated and characterized (7).…”

Genetic characterisation and heterologous expression of leucocin C, a class IIa bacteriocin from Leuconostoc carnosum 4010

“…Peptides in subgroup 3 as well as enterocin SE-K4 and carnobacteriocin B2 in subgroup 4 exceptionally have neither the conserved tryptophan at the C-tails, nor the cysteine residues to form the C-terminal disulfide bridge (Table 2). Marrec et al 2000Metivier et al 1998Aymerich et al 1996Henderson et al 1992Marugg et al 1992Tichaczek et al 1994Kalmokoff et al 2001Birri et al 2010Feng 2009Kawamoto et al 2002Bennik et al 1998Yamazaki et al 2005Bhugaloo-Vial et al 1996Jack et al 1996Vaughan et al 2001Fimland et al 2002bHeng et al 2007 Subgroup 2 Kwaadsteniet et al 2006Quadri et al 1995Eguchi et al 2001Diep et al 2006 The YGNGV/L "pediocin box" is marked (bold), the leucine residue (L), odd, and uncertain amino acids (X) are marked as bold and red. Names of the six newly identified class IIa bacteriocins are in red (Rea et al 2011).…”