International Journal of Antimicrobial Agents 25 (2005) 508–513 An antibacterial and antiviral peptide produced by Enterococcus mundtii ST4V isolated from soya beans Svetoslav D. Todorov a ,M´ onica B. Wachsman b , Hendri¨ ette Knoetze a , Martina Meincken c , Leon M.T. Dicks a,∗ a Department of Microbiology, Stellenbosch University, 7600 Stellenbosch, South Africa b Laboratorio de Virologia, Departamento de Quimica Biologica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 2, Piso 4, 1428 Buenos Aires, Argentina c Institute for Polimer Science, Stellenbosch University, 7600 Stellenbosch, South Africa Received 19 November 2004; accepted 9 February 2005 Abstract Enterococcus mundtii ST4V, isolated from soya beans, produces a 3950Da antibacterial peptide active against Gram-positive and Gram- negative bacteria, including Enterococcus faecalis, Streptococcus spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae and Staphylococcus aureus. The peptide also inactivated the herpes simplex viruses HSV-1 (strain F) and HSV-2 (strain G), a polio virus (PV3, strain Sabin) and a measles virus (strain MV/BRAZIL/001/91, an attenuated strain of MV). MV, HSV-1 and HSV-2 were 95.5%–99.9% inactivated by peptide ST4V at 400 g/ml. Monkey kidney Vero cells were not inactivated, even at four times the level peptide ST4V displayed antiviral activity, indicating that the effect was not due to cytotoxicity. Complete inactivation or significant reduction in antimicrobial activity was observed after treatment of peptide ST4V with Proteinase K, pronase, pepsin and trypsin. No change in antimicrobial activity was recorded after treatment with -amylase, suggesting that peptide ST4V was not glycosylated. This is the first description of an antibacterial and antiviral peptide with such broad-spectrum of activity, produced by a lactic acid bacterium. © 2005 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved. Keywords: Antibacterial and antiviral peptide; Enterococcus mundtii 1. Introduction Lactic acid bacteria (LAB) are well known for their production of antimicrobial compounds, including an- tibacterial peptides, collectively known as bacteriocins [1]. Bacteriocins are usually active against strains closely related to the producer organism or against bacteria from the same ecological niche [2,3]. However, a few broad-spectrum antibacterial peptides with activity against Gram-negative bacteria have been described, e.g. plantaricin 35d produced by Lactobacillus plantarum [4], bacteriocin ST151BR pro- duced by Lactobacillus pentosus ST151BR [5], a bacteriocin produced by Lactobacillus paracasei subsp. paracasei [6], thermophylin produced by Streptococcus thermophylus [7], ∗ Corresponding author. Fax: +27 21 8085846. E-mail address: lmtd@sun.ac.za (L.M.T. Dicks). peptide AS-48 produced by Enterococcus faecalis [8], a bac- teriocin produced by Lactococcus lactis KCA2386 [9] and enterocin CRL35 produced by Enterococcus faecium [10]. Several bacteriocins have been described for the members of the genus Enterococcus [11]. Wachsman et al. [12] were the first to describe an antiviral peptide produced by E. fae- cium. The peptide, 3.5 kDa in size, inhibited late stages of the HSV-1 and HSV-2 multiplication cycle [13]. A year later, Serkedjieva et al. [14] described a 5.0 kDa-peptide produced by Lactobacillus delbrueckii subsp. bulgaricus, with activity against the A/chicken/Germany influenza virus, strain Wey- bridge (H7N7) (A/Weybridge), and strain Rostock (N7N1) (A/Rostock). In this paper, the first broad-spectrum antibacterial and antiviral peptide, produced by a strain of Enterococcus mundtii, is described. The broad-spectrum of activity, espe- cially against pathogenic bacteria, renders the peptide ideal 0924-8579/$ – see front matter © 2005 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved. doi:10.1016/j.ijantimicag.2005.02.005