Pediocin SA-1: A selective bacteriocin for controlling Listeria monocytogenes in maize silages

Journal of Dairy Science, 99 (2016) 8070–8080

http://dx.doi.org/10.3168/jds.2016-11121

In this study, we assessed the potential as silage additive of a bacteriocin produced by Pediococcus acidilactici Northern Regional Research Laboratory (NRRL) B-5627 (pediocin SA-1). Maize was inoculated either with a bacterial starter alone (I) or in combination with the bacteriocin (IP), and untreated silage served as control. We monitored the products of fermentation (ethanol, and lactic and acetic acids), the microbial population, and the presence of the indicator strain Listeria monocytogenes Colección Española de Cultivos Tipo (CECT) 4032 (1 × 105 cfu/g) after 1, 2, 5, 8, 16, and 30 d of ensiling. Our results indicated antilisterial activity of the bacteriocin, anticipating the disappearance of L. monocytogenes in IP compared with I and control silages. The PCR-denaturing gradient gel electrophoresis analysis revealed the addition of the bacteriocin did not affect the bacterial communities of the spontaneous fermentation, and the inoculant-containing bacteria (Lactobacillus plantarum, Lactobacillus buchneri, and Enterococcus faecium) were found in addition to the bacterial communities of untreated maize silages in I and IP silages. Both treatments increased the concentration of antimicrobial compounds (acetic acid, ethanol, and 1,2-propanodiol) and led to lower residual sugar contents compared with the control, which would provide enhanced aerobic stability. The fact that the identified species L. plantarum, L. buchneri, and E. faecium produce some of these inhibitory compounds, together with their persistence throughout the 30 d of fermentation, suggest these bacteria could actively participate in the ensiling process. According to these results, pediocin SA-1 could be used as an additive to control the presence of L. monocytogenes in maize silages selectively, while improving their fermentative quality and eventually their aerobic stability.

Production of four potentially probiotic lactic acid bacteria and their evaluation as feed additives for weaned piglets

Animal Feed Science and Technology, (1–2), 2007, 89–107

http://dx.doi.org/10.1016/j.anifeedsci.2006.05.010

The present study was conducted to study the production and evaluation of potentially probiotic additives containing both live lactic acid bacteria (Pediococcus acidilactici NRRL B-5627, Lactococcus lactis subsp. lactis CECT 539, Lactobacillus casei subsp. casei CECT 4043 and Enterococcus faecium CECT 410) and antimicrobial metabolites with could be used as a replacement for antibiotics in weanling pig diets. The gastrointestinal transit tolerance of the four bacteria was determined by exposing washed cell suspensions at 30 °C to acidic conditions (pH 1.0, 2.0, 3.0, 4.0 and 5.0), to a simulated gastric juice (pH 2.0) containing pepsin (3 g/L) and sodium chloride (5 g/L), and to a simulated small intestinal juice (pH 8.0) containing pancreatin (1 g/L) and sodium chloride (5 g/L), mimicking the gastrointestinal environment. These studies showed that the four strains are capable of surviving the passage through the gastrointestinal conditions. Therefore, the production of biomass and antimicrobial products by these bacteria was performed in whey using a fed-batch fermentation technique that provided enhanced productions compared to those obtained in batch fermentations. The obtained fed-batch cultures preserved at −20 °C with skim milk showed a good viability after 3 months of storage. The four cultures exhibited low losses of viability in the piglet feed during their storage at room temperature for 8 days. These results offered the possibility of using the piglet feed as a vehicle to administer the four probiotic bacteria. The effects of the supplementation of separate potentially probiotic cultures and an antibiotic (colistin sulfate) to piglet diets on body weight gain, feed intake, feed efficiency and on the faecal coliform counts of weaned piglets were also studied. Although the best results were obtained in the groups receiving the antibiotic, a significant increase in body weight gain and final body weight was obtained in the groups fed diets supplemented with lactic acid bacteria as compared with the non-treated (controls) groups (P=0.05). The changes in the total coliform population in the control groups over time were not significant (P<0.05), while in the groups fed probiotics and antibiotic, the viable coliform counts significantly dropped at the last sampling (P<0.05). These results suggest that the lactic acid bacteria used in this study could be used as suitable strains for widespread use in the pig industry.