Enhancement of the enterocin CRL35 activity by a synthetic peptide derived from the NH2-terminal sequence.

The enterocin CRL35 biosynthetic gene cluster was cloned and sequenced. The sequence was revealed to be highly identical to that of the mundticin KS gene cluster (S. Kawamoto, J. Shima, R. Sato, T. Eguchi, S. Ohmomo, J. Shibato, N. Horikoshi, K. Takeshita, and T. Sameshima, Appl. Environ. Microbiol. 68:3830-3840, 2002). Short synthetic peptides were designed based on the bacteriocin sequence and were evaluated in antimicrobial competitive assays. The peptide KYYGNGVSCNKKGCS produced an enhancement of enterocin CRL35 antimicrobial activity in a buffer system.

Enterocin CRL35 inhibits late stages of HSV-1 and HSV-2 replication in vitro.

The replication of herpes simplex virus (HSV) type 1 and 2 in Vero cells is inhibited in the presence of enterocin CRL35 (ECRL), a bacteriocin produced by Enterococcus faecium CRL35. Attempts to resolve the mode of action of ECRL indicate that virus adsorption and penetration are not affected. Instead, a late step of virus multiplication is hindered since the addition of 100 microg/ml of ECRL at 8h post infection still causes a 90% inhibition of virus release. The effect of ECRL on HSV antigen expression was studied by immunofluorescence using a polyclonal serum and a monoclonal antibody against glycoprotein D (gamma protein). These studies indicated that ECRL impeded the second round of infection, apparently as a consequence of the inhibition of glycoprotein D expression. The replication of syncytial mutants of HSV-1 was significantly inhibited at a ECRL concentration of 25 microg/ml. Both the percentage of fused cells and the polykaryocyte size were affected. Studies on the effect of ECRL on viral protein synthesis showed that in the presence of ECRL, HSV late gamma proteins were not synthesized. From these findings, it is concluded that inhibition of HSV spreading by ECRL is due to the prevention of mainly late glycoprotein synthesis.

Use of Bacterial Cultures in the Ripening of Fermented Sausages.

Pure bacterial cultures were used in the production of Argentina salami, the most popular cured meat product in the country. Three selected groups of two strains each of Lactobacillus plantarum and Micrococcus varians were used as a starter cultures, with two different sugar concentrations. Apart from the use of these starter cultures, the salami was manufactured under the same conditions normally used in industrial production. When 0.6% sucrose was used, the levels of L. plantarum and M. varians were 108 and 107 CFU/g, respectively, on the second day of ripening. Similar levels of lactic acid bacteria were found in non-inoculated sausages at 2 d post-preparation. Under these conditions, coliforms decreased significantly. The final pH of the inoculated and uninoculated sausage were 5.0 and 5.2, respectively, after 7 d of ripening. When 0.9% glucose plus 0.6% sucrose was added, the level of lactic acid bacteria was 109 CFU/g on the second day, a value that remained constant in the inoculated sausages to the end of the ripening period. Staphylococci showed a marked decrease in population, while coliforms disappeared on the second or third day. The final pH of 4.40 or 4.55 was reached within 4 d. The product obtained under these conditions had a firm texture, a good slicing surface and pleasant flavor and aroma. The use of starter cultures in cured dry Argentine-style sausage shortened the ripening period from 14 to 7 d.

Microflora of Tafí Cheese: Changes During Manufacture and Maturation.

Changes in microbial flora during the manufacture and maturation of Argentine Tafí cheese was examined. The microbial flora was found to be predominantly mesophilic streptococci, leuconostocs and homofermentative lactobacilli. Streptococcus lactis predominated on the surface and in the internal portion of the cheese after pressing. Streptococcus cremoris reached its maximum population after salting. The main microbial types during maturation were Lactobacillus casei and Lactobacillus plantarum . Pathogenic microorganisms were not detected in any of the samples analyzed.