Characterization of a bacteriocin produced by Enterococcus faecium GM-1 isolated from an infant

Abstract

Aim: To partially characterize the bacteriocin produced by the GM-1 strain of Enterococcus faecium, isolated from the faeces of a newborn human infant. Methods and Results: The bacteriocin produced by E. faecium GM-1 showed a broad spectrum of activity against indicator strains of Escherichia coli, Staphylococcus aureus, Vibrio spp., Salmonella typhimurium, Listeria monocytogenes, Lactobacillus acidophilus, and Streptococcus thermophilus. Treatment of the GM-1 bacteriocin with proteolytic enzymes reduced its inhibitory activities. The bacteriocin was stable at 100°C for 20 min and displayed inhibitory activity at neutral pH. The optimal production of bacteriocin from E. faecium GM-1 was obtained when the culture conditions were pH 6AE0-6AE5 and 35-40°C. The inhibitory activity of the bacteriocin was not substantially changed by the use of different carbon sources in the media, except when galactose was substituted for glucose. The use of a sole nitrogen source caused a decrease in inhibitory activity. A bacteriocin gene similar to enterocin P was identified from the total DNA of E. faecium GM-1 by PCR and direct sequencing methods. Conclusion: E. faecium GM-1, which was isolated from the faeces of a newborn baby, produces an enterocin P-like bacteriocin with inhibitory activity against Gram-positive and Gram-negative bacteria, including food-borne pathogens. Significance and Impact of the Study: E. faecium GM-1, isolated from infant faeces, produces a new bacteriocin that is similar to enterocin P. This bacteriocin is heat stable and has a broad antibacterial spectrum that includes both Gram-positive and Gram-negative bacteria.

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

“…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]. Our fi ndings are in agreement with these studies showing that bacteriocin producing enterococci can be found associated with gastrointestinal tract of human.…”

Influence of Enterococci and Lactobacilli on Listeria

“…Each enzyme was dissolved in sterile demineralised water and added to the CFNS to the final concentration of 1.0 mg/ml. Following incubation, at 37°C for 2 h, the reaction mixtures were heated to 100°C for 10 min to inactivate the enzymes before assessing the remaining bacteriocin activity against selected indicator strains (Kang & Lee 2005).…”

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

“…Enterococcal bacteriocins, often termed enterocins, have been widely investigated, mainly because they are active against gram-positive food-borne pathogens, such as Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus. The vast majority of enterocins are active only against gram-positive bacteria (10, 17); however, some exceptions with broad activity spectra described in recent years showed the ability to inhibit the growth of gram-negative microorganisms (5,11,13).…”

“…Enterococcal bacteriocins, often termed enterocins, have been widely investigated, mainly because they are active against gram-positive food-borne pathogens, such as Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus. The vast majority of enterocins are active only against gram-positive bacteria (10, 17); however, some exceptions with broad activity spectra described in recent years showed the ability to inhibit the growth of gram-negative microorganisms (5,11,13).The increasing number of enterocins reported in the literature and the emergence of novel structures that could not be included in classical bacteriocin classifications (12,14,17) prompted the grouping of enterocins into a new four-class scheme by Franz et al (8). Most enterocins known so far were included in class II (small, nonlantibiotic peptides), which was divided into three subgroups: class II.1, enterocins of the pediocin family; class II.2, enterocins synthesized without a leader peptide; and class II.3, other linear, non-pediocin-like enterocins.…”