Effects of feeding of two potentially probiotic preparations from lactic acid bacteria on the performance and faecal microflora of broiler chickens

The aim of this study was to evaluate the potential of two probiotic preparations, containing live lactic acid bacteria (Lactococcus lactis CECT 539 and Lactobacillus casei CECT 4043) and their products of fermentation (organic acids and bacteriocins), as a replacement for antibiotics in stimulating health and growth of broiler chickens. The effects of the supplementation of both preparations (with proven probiotic effect in weaned piglets) and an antibiotic (avilamycin) on body weight gain (BWG), feed intake (FI), feed consumption efficiency (FCE), relative intestinal weight, and intestinal microbiota counts were studied in 1- day posthatch chickens. The experiments were conducted with medium-growth Sasso X44 chickens housed in cages and with nutritional stressed Ross 308 broiler distributed in pens. Consumption of the different diets did not affect significantly the final coliform counts in Sasso X44 chickens. However, counts of lactic acid bacteria and mesophilic microorganisms were higher in the animals receiving the two probiotic preparations (P < 0.05). In the second experiment, although no differences in BWG were observed between treatments, Ross 308 broilers receiving the probiotic Lactobacillus preparation exhibited the lowest FCE values and were considered the most efficient at converting feed into live weight.Instituto Nacional de Investigación y Tecnología Agraria | Ref. CAL01-045-C2-

Modelling the biphasic growth and product formation by Enterococcus faecium CECT 410 in realkalized fed-batch fermentations in whey

The influence of initial pH on growth and nutrient (total sugars, nitrogen, and phosphorous) consumption by Enterococcus faecium CECT 410 was studied during batch cultures in whey. With these data, two realkalized fed-batch fermentations were developed using different feeding substrates. The shift from homolactic to mixed acid fermentation, the biphasic kinetics observed for cell growth and nitrogen consumption and the increase in the concentrations of biomass and products (lactic acid, acetic acid, ethanol, and butane-2,3-diol) were the most noteworthy observations of these cultures. Modelling the fed-batch growth of Ent. faecium with the Logistic and bi-Logistic models was not satisfactory. However, biomass production was best mathematically described with the use of a double Monod model, which was expressed in terms of biomass, product accumulation, and nitrogen utilization. Product formation was successfully modelled with a modified form of the Luedeking and Piret model developed in this study.Instituto Nacional de Investigación y Tecnología Agraria | Ref. CAL01-045-C2-2Ministerio de Educación y Ciencia | Ref. MAT2005-05393-C03-03Ministerio de Educación y Ciencia | Ref. MAT2006-11662- C03-0

Evaluation of two bacteriocin-producing probiotic lactic acid bacteria as inoculants for controlling Listeria monocytogenes in grass and maize silages

This study evaluated the effectiveness as silage inoculants of two bacteriocin-producing lactic acid bacteria (LAB) with proven probiotic activity in post-weaned piglets, Lactococcus lactis CECT 539 and Pediococcus acidilactici NRRL B-5627, in combination with the ensiling strain Lactobacillus plantarum CECT 220. Four combinations of LAB were tested in grass and maize silages: L. plantarum (Lb), L. plantarum + L. lactis (LbL), L. plantarum + P. acidilactici (LbP), and the three species together (LbLP). Untreated silages and silages inoculated with commercial starters (L. plantarum + Lactobacillus buchneri + Enterococcus faecium) were prepared and used as controls. Since both bacteriocinogenic strains have shown antilisterial activity in vitro, this study also aimed to determinate their effectiveness for controlling Listeria monocytogenes in the silo. Therefore, silages were inoculated with the strain L. monocytogenes CECT 4032 (1.0 × 105 cfu/g), the evolution of which was monitored throughout fermentation using microbiological and DNA based methods. Each treatment was assayed in triplicate in lab-scale silos and sampled after 1, 2, 8, 16 and 30 days to extract DNA and determination of the pH, volume, organic acids (lactic, acetic, propionic and butyric), alcohols (ethanol and propane-1, 2-diol), water soluble reducing sugars (WSRS) and make LAB and L. monocytogenes counts. Our results showed that the silages treated with bacteriocin-producing LAB had a higher rate of pH decline (P < 0.01) and lactic acid production (P < 0.01). After 30 days of fermentation, we observed low acetic acid (P < 0.01) and ethanol (P < 0.01), lower LAB counts (P < 0.01) and higher (P < 0.01) residual sugar concentrations in the Lb, LbL, LbP and LbLP silages. No L. monocytogenes colonies were found during ensilage; however, its DNA was present, which suggests that the adverse silage conditions (pH, anaerobiosis) might favour a viable but non-culturable state in the cells. In both forages, all treatments showed the anticipated disappearance of L. monocytogenes, unlike the control. It can be concluded that the bacteriocinogenic LAB tested in this study can be used as silage inoculants for controlling L. monocytogenes in the silo and also in the rumen of cattle due to their reported tolerance to acid.Xunta de Galicia | Ref. 03MFU0

Evaluation of a chitosan-based edible film as carrier of natamycin to improve the storability of Saloio cheese

The purpose of this study was to evaluate the effects of the application of chitosan coating containing natamycin on the physicochemical and microbial properties of semi-hard cheese. Three cheese groups were prepared: samples without coating, samples coated with chitosan and with chitosan containing 0.50 mg mL1 of natamycin, whose minimum inhibitory concentration was previously determinated on cheese surface. Microbiological analyses showed that natamycin coated samples presented a decrease on moulds/yeasts of 1.1 log (CFU g1) compared to control after 27 days of storage. Addition of natamycin also affected O2 and CO2 permeability, increasing from 7.12 to 7.68 × 1015 g·(Pa s m)1, and from 10.69 to 64.58 × 1014 g·(Pa s m)1, respectively. The diffusion coefficient values of natamycin from the film to phosphate buffered saline solution and to the cheese were 3.60 × 1010 and 1.29 × 1012 cm2 s1, respectively. This study demonstrated that chitosan-based coating/films can be used as release system containing natamycin to create an additional hurdle for moulds/yeasts in cheese thus contributing to extend its shelf-life.Fundação para a Ciência e a Tecnologia | Ref. SFRH/BD/32566/200