Browsing by Author "Mare, Louise"
Now showing 1 - 1 of 1
Results Per Page
Sort Options
- ItemProbiotic properties of lactic acid bacteria evaluated in a gastro-intestinal model and in in vivo pig trials(Stellenbosch : Stellenbosch University, 2005-03) Mare, Louise; Dicks, Leon Milner Theodore; Wolfaardt, Gideon M.; Stellenbosch University. Faculty of Science. Dept. of Microbiology.ENGLISH ABSTRACT: This study describes the use of a gastro-intestinal model to screen lactic acid bacteria isolated from the gastro-intestinal tract of post-weaned piglets (raised on six different diets) for probiotic properties. Intestinal bacteria were isolated from ,the stomach, duodenum, jejunum, caecum, ileum and colon. The highest cell numbers (6 x 107 cfulg) were isolated from the ileum. No significant differences in viable cell counts were recorded for piglets raised on the six diets. Isolates with the best overall probiotic properties were identified as members of Lactobacillus salivarius and Lactobacillus fermentum. The two strains selected for further studies were Lactobacillus plantarum 423 (originally isolated from sorghum beer) and Lactobacillus salivarius 241 (isolated from pig intestine). Enterococcus faecalis FAIR E 92 was originally isolated from pig intestine and was included in this study as a non-pathogenic challenge strain. L. plantarum 423 produces a bacteriocin plantaricin 423, active against E. faecalis FAIRE 92. L. plan/arum 423 and L. salivarius 241 were included in the gastro-intestinal model and their adhesion to the mucus of porcine ileum studied with fluorescent-in-si/u-hybridization (FISH). A decrease in viable cell numbers of L. plan/arum 423 was recorded in the duodenum, jejunum and ileum in the presence of bile and pancreatic juice. However, higher cell numbers were recorded in the caecum and anterior colon, which suggested that strain 423 recovered from these stress factors. Plantaricin 423 was detected for up to 28 hours in the duodenum, jejunum, ileum and middle colon. Lower cell numbers (one log unit) of L. salivarius 241 were recorded in the gastro-intestinal model over seven days, compared to strain 423. Piglets of one, 14 and 28-days-old were dosed with L. plan/arum 423 and L. salivarius 241, separately and in combination (1: 1). In a separate experiment, 14-day-old piglets were challenged twice with E. faecalis FAIRE 92, followed by dosage with strains 423 and 241. New-borne piglets dosed with L. plantarum 423 gained more weight (4 kg over 19 days) compared to piglets dosed with L. salivarius 241 (2.2 kg over 19 days), or a combination of the two strains (2 kg over 19 days). Piglets of 14 and 28-days-old, on the other hand, gained more weight when dosed with a combination of strains 423 and 241. The cell numbers of E. faecalis FAIR E 92 and other enterococci decreased drastically (two log units) when the piglets were dosed with the latter two strains. Overall, piglets of various ages reacted differently when administered L. plantarum 423 and L. salivarius 241, separately or in combination. Fluorescent-in-situ-hybridization (FISH) was used to study the in vivo adhesion of L. plantarum and L. salivarius to mucus in the stomach, duodenum, jejunum, ileum, caecum and colon. The highest number of L. plantarum cells was recorded in the ileum, whereas L. salivarius favoured adhesion to the duodenum. A decrease in cell numbers of E. faecalis in the ileum mucus was recorded when a combination of the probiotic strains 423 and 241 was administered. This study provided a reliable estimation of the presence and/or adhesion of L. plantarum and L. salivarius to various parts of the porcine gastro-intestinal tract, without the use of expensive cultivation techniques. Insight was gained into the co-evolution existing between probiotic bacteria and the porcine gastro-intestinal tract, emphasizing the use of gastro-intestinal models to study the dynamics of the gastro-intestinal tract.