Abstract
The aims of this study were to identify bacteriocinogenic activity in 13 enterococci isolated from fecal samples of wild South American (Arctocephalus australis) and Subantarctic fur seals (Arctocephalus tropicalis); to determine the physicochemical characteristics and antimicrobial spectrum of antimicrobial compounds against Gram-positive and Gram-negative bacteria; and to evaluate the presence of bacteriocin structural genes by PCR. Out of 13 enterococci screened for antimicrobial activity, five enterococci showed activity against Listeria monocytogenes ATCC 35152, an important pathogen linked to food. Of these, only the E. mundtii strain J5 maintained the activity after the pH was adjusted (pH 6.5). The activity of antimicrobial compounds from the E. mundtii strain J5 (ACs-J5) was lost after proteolytic enzyme treatment; however, the activity was maintained after heat, pH (acidic and basic conditions) and chemical treatment. ACs-J5 showed narrow spectrum activity. Only the mundticin KS gene was detected in the J5 strain and no plasmid was present. In conclusion, the properties presented by ACs-J5 make it a valuable biopreservative in food industries in avoiding pathogenic microorganisms such as L. monocytogenes and it should be a good candidate for probiotic application. Key words: Antimicrobial compounds, Enterococcus mundtii, wild fur seal, antilisterial activity.
Highlights
In recent years, natural antimicrobials, such as bacteriocins, have received a good deal of attention over a number of microorganism control issues (MaldonadoBarragán et al, 2016; Gao et al, 2016), ribosomally synthesized antimicrobial peptides and proteins that usually only show inhibitory activity to closely related bacterial species
According to Nes et al (2014), Class II can be further divided into four subgroups: Class IIa; Class IIb; the circular bacteriocins; and the leaderless bacteriocins Bacteriocinogenic enterococci strains have been found in foods, such as fresh milk, and fecal samples from humans and animals
The aims of this study were to identify bacteriocinogenic enterococci strains isolated from fecal samples of wild South American (Arctocephalus australis) and Subantarctic fur seals (Arctocephalus tropicalis), to determine the physicochemical characteristics and the spectrum of antimicrobial compounds and to evaluate the presence of enterocin genes by PCR
Summary
Natural antimicrobials, such as bacteriocins, have received a good deal of attention over a number of microorganism control issues (MaldonadoBarragán et al, 2016; Gao et al, 2016), ribosomally synthesized antimicrobial peptides and proteins that usually only show inhibitory activity to closely related bacterial species. According to Nes et al (2014), Class II can be further divided into four subgroups: Class IIa (the pediocin-like and strong antilisterial enterocins); Class IIb (the twopeptide bacteriocins); the circular bacteriocins; and the leaderless bacteriocins (synthesized without a leader peptide) Bacteriocinogenic enterococci strains have been found in foods, such as fresh milk, and fecal samples from humans and animals. The enterococcal bacteriocins proved to be active against gram-positive foodborne pathogens, such as Listeria monocytogenes, Staphylococcus aureus and Clostridium spp. (Nes et al, 2014)
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