Recent review on bacterioins
Production, characterization, and antimicrobial activity of a bacteriocin from newly isolated Enterococcus faecium IJ-31. J Food Prot. 2010 Jan;73(1):44-52 Authors: Javed I, Ahmed S, Manam S, Riaz M, Ahmad B, Ali MI, Hameed A, Chaudry GJ This work aimed to isolate and characterize Enterococcus spp. from indigenous dairy products in Islamabad, Pakistan. By classical microbiological techniques, one strain from a butter sample was identified to be Enterococcus faecium, and we designated it E. faecium IJ-31. The precise identity of this strain was then established by determining the sequence of its 16S and 23S rRNA genes. The sequence homology searches revealed matches with a number of previously reported strains, such as E. faecium HN-N3 and HN-N29, both isolated from swine intestines in China. The newly isolated strain was tested for hemolysis and antibiotic sensitivity; it was nonhemolytic on sheep and human blood and sensitive to vancomycin. Consistent with its vancomycin sensitivity, repeated attempts to amplify the vancomycin resistance genes vanA and vanB failed. Similar attempts to amplify the virulence genes gelE, agg, and cyl also failed, suggesting the absence of these genes. In contrast, the enterocin-P gene, entP, readily amplified with primers based on the previously reported sequences, and the deduced sequence showed near identity with a number of reported sequences from E. faecium. Further, the 71-residue enterocin-P sequence from strain IJ-31 is only the second complete sequence reported. The enterocin was partially purified and tested for antibacterial activity. It showed potent inhibitory activity against many bacteria, including Listeria monocytogenes, a routinely used test strain. Further, the enterocin showed potent activity against Bacillus subtilis and Bacillus cereus. The enterocin retained antibacterial activity even following heating to 121 degrees Celsius for 15 min. Further, it also retained activity after exposure to pH values ranging from 4 to 10. However, proteinase K treatment rendered the peptide nonfunctional. PMID: 20051203 [PubMed - indexed for MEDLINE]
Increased inactivation of exopolysaccharide-producing Pediococcus parvulus in apple juice by combined treatment with enterocin AS-48 and high-intensity pulsed electric field. J Food Prot. 2010 Jan;73(1):39-43 Authors: Martínez Viedma P, Sobrino López A, Ben Omar N, Abriouel H, Lucas López R, Martín Belloso O, Gálvez A The cyclic peptide bacteriocin enterocin AS-48 was tested (at final concentrations of 0.175, 0.613, and 1.05 AU/ml) against the exopolysaccharide-producing cider spoilage strain Pediococcus parvulus 48 in apple juice in combination with high-intensity pulsed electric field (HIPEF) treatment (35 kV/cm and 150 Hz for 4 mus and bipolar mode). The effect of the combined treatments was studied by surface response methodology, with AS-48 concentration and HIPEF treatment time as process variables. A bacteriocin concentration of 0.613 AU/ml in combination with HIPEF treatment time of 1,000 micros reduced the population of pediococci by 6.6 log cycles in apple juice and yielded an apple juice that was free from pediococci during a 30-day storage period at 4 and 22 degrees Celsius. In contrast, application of HIPEF treatment alone had no effect on the surviving pediococci during storage of juice at 22 degrees Celsius. The combined treatment significantly improved the stability of the juice against spoilage by exopolysaccharide-producing P. parvulus. PMID: 20051202 [PubMed - indexed for MEDLINE] |
