Enterococcus faeciumF58, a bacteriocinogenic strain naturally occurring in Jben, a soft, farmhouse goat's cheese made in Morocco

Abstract

Aims: Characterization of Ent F-58 produced by Enterococcus faecium strain F58 isolated from Jben, a soft, farmhouse goat's cheese manufactured without starter cultures. Methods and Results: E. faecium strain F58 was isolated because of its broad inhibitory spectrum, including activity against food-borne pathogenic and spoilage bacteria. The antimicrobial substance was produced during the growth phase, with maximum production after 16-20 h of incubation at 30°C, and was stable over a wide pH range (4-8) and at high temperatures (5 min at 100°C). The enterocin was purified to homogeneity using cation exchange and hydrophobic interaction on C-18 and reverse-phase high-performance liquid chromatography. The activity was eluted as two individual active fractions (F-58A and F-58B) and matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry analysis showed masses of 5210AE5 and 5234AE3 Da respectively. Both peptides were partially sequenced by Edman degradation, and amino-acid sequencing revealed high similarity with enterocin L50 (I). PCR-amplified fragments containing the structural genes for F-58 A and B were located in a 22-kb plasmid harboured by this strain. We verified that it also holds the structural gene for P-like enterocin. Conclusion: E. faecium strain F58 from Jben cheese, a producer of enterocin L50, exerts an inhibitory effect against strains of genera such as Listeria, Staphylococcus, Clostridium, Brochothrix and Bacillus. Enterocin was characterized according to its functional and biological properties, purification to homogeneity and an analysis of its amino acid and genetic sequences. Significance and Impact of the Study: E. faecium strain F58 is a newly discovered producer of enterocin L50, the biotechnological characteristics of which indicate its potential for application as a protective agent against pathogens and spoilage bacteria in foods.

Purification and characterization of enterocin FH 99 produced by a faecal isolate Enterococcus faecium FH 99

“…It could, therefore, be tentatively classifi ed as class II bacteriocin [5]. The low molecular weight of enterocin in this study is in accordance with molecular weight of enterocins reported by various workers [21,29], but they differed from the higher molecular weight enterocins described by others [3,38].…”

“…Large size plasmids of size 49 kb and >70 kb respectively, along with other low molecular weight plasmids have been reported in enterococci by various workers [21,39].…”

“…The sensitivity of bacteriocins of LAB to various proteolytic enzymes and insensitivity to non-proteolytic enzymes has been reported widely [21,29]. Bacteriocin of FH 99 was found to retain its activity after treatment with rennin.…”

“…faecium and Ent. faecalis strains from dairy products and/or silage displaying antibacterial activity have been isolated [20][21][22]. Isolation of bacteriocinogenic enterococci from faeces of human and animal have also been well reported [23][24][25].…”

“…faecalis MR99 [29] and have been purifi ed by cation-exchange chromatography to a greater extent [21,34,35]. Several workers have reported >50% recovery of antibacterial activity by gel fi lteration and cation-exchange chromatography of the crude bacteriocin [29,35].…”