In Vitro Assessment of Bioactivities of Lactobacillus Strains as Potential Probiotics for Humans and Chickens.

Twelve previously isolated Lactobacillus strains were investigated for their in vitro bioactivities, including bile salt hydrolase (BSH), cholesterol-reducing and antioxidant activities, cytotoxic effects against cancer cells, enzyme activity, and biogenic amine production. Among them, only 4 strains showed relatively high BSH activity, whereas the rest exhibited low BSH activity. All 12 strains showed cholesterol-reducing and antioxidant activities, especially in their intact cells, which in most of the cases, the isolated strains were stronger in these activities than the tested commercial reference strains. None of the tested strains produced harmful enzymes (ß-glucosidase and ß-glucuronidase) or biogenic amines. Among the 12 strains, 3 strains were tested for their cytotoxic effects against 3 cancer cell lines, which exhibited strong cytotoxic effects, and they also showed selectivity in killing cancer cells when compared to normal cells. Hence, all 12 Lactobacillus strains could be considered good potential probiotic candidates because of their beneficial functional bioactivities. PRACTICAL APPLICATION: The Lactobacillus strains tested in this study could be considered good potential probiotic candidates for food/feed industry because of their beneficial functional bioactivities such as good cholesterol-reducing ability, high antioxidant activity, and good and selective cytotoxic effect against cancer cells.

Changes in rumen protozoal community by condensed tannin fractions of different molecular weights from a Leucaena leucocephala hybrid in vitro.

AIMS: To evaluate the effects of condensed tannins (CTs) fractions of differing molecular weights (MWs) from a Leucaena leucocephala hybrid-Rendang on the rumen protozoal community in vitro. METHODS AND RESULTS: The effects of unfractionated CTs (F0) and CT fractions of different MWs (F1 > F2 > F3 > F4 > F5) on protozoal population and community were evaluated in vitro using rumen microbes and ground guinea grass as the substrate. Higher-MW CT fractions F1 and F2 significantly (P < 0·05) decrease the number of ciliate protozoa. The real-time PCR analysis showed that the total protozoa was significantly (P < 0·05) lower in F0 and all CTs with fractions F1 and F2 having the lowest value. High-throughput sequencing of the partial 18S rRNA gene showed that the genus Entodinium significantly (P < 0·05) decreased with increasing MWs of CT, whereas Anoplodinium-Diplodinium were significantly (P < 0·05) increased. Inclusion of the highest MW CT fraction F1 decreased the relative abundance of the minor genera such as Eudiplodinium and Polyplastron compared to the control and CT fractions F2-F5. CONCLUSION: CTs of differing MWs could reduce and alter the rumen protozoa population in vitro. This effect was more pronounced for higher-MW CTs. SIGNIFICANCE AND IMPACT OF THE STUDY: The high MW CTs should be considered as a feed supplement in the ruminant diet to reduce the protozoal population which are known to be associated with methanogens as a means to mitigate methane production in the rumen.

Efficacy of a bacteriophage isolated from chickens as a therapeutic agent for colibacillosis in broiler chickens.

The efficacy of bacteriophage EC1, a lytic bacteriophage, against Escherichia coli O78:K80, which causes colibacillosis in poultry, was determined in the present study. A total of 480 one-day-old birds were randomly assigned to 4 treatments groups, each with 4 pens of 30 birds. Birds from the control groups (groups I and II) received PBS (pH 7.4) or 10(10) pfu of bacteriophage EC1, respectively. Group III consisted of birds challenged with 10(8) cfu of E. coli O78:K80 and treated with 10(10) pfu of bacteriophage EC1 at 2 h postinfection, whereas birds from group IV were challenged with 10(8) cfu of E. coli O78:K80 only. All the materials were introduced into the birds by intratracheal inoculation. Based on the results of the present study, the infection was found to be less severe in the treated E. coli-challenged group. Mean total viable cell counts of E. coli identified on eosin methylene blue agar (designated EMB + E. coli) in the lungs were significantly lower in treated, E. coli-challenged birds than in untreated, E. coli-challenged birds on d 1 and 2 postinfection. The EMB + E. coli isolation frequency was also lower in treated birds; no E. coli was detectable in blood samples on any sampling day, and E. coli were isolated only in the liver, heart, and spleen of treated chickens at a ratio of 2/6, 1/6, and 3/6, respectively, at d 1 postinfection. The BW of birds from the E. coli-challenged group treated with bacteriophage EC1 were not significantly different from those of birds from both control groups but were 15.4% higher than those of the untreated, E. coli-challenged group on d 21 postinfection. The total mortality rate of birds during the 3-wk experimental period decreased from 83.3% in the untreated, E. coli-challenged birds (group IV) to 13.3% in birds treated with bacteriophage EC1 (group III). These results suggest that bacteriophage EC1 is effective in vivo and could be used to treat colibacillosis in chickens.

Effects of beta-glucanase-producing Lactobacillus strains on growth, dry matter and crude protein digestibilities and apparent metabolisable energy in broiler chickens.

The effects of beta-glucanase expressed by transformed Lactobacillus strains on growth performance, apparent digestibilities of dry matter and crude protein, and apparent metabolisable energy were studied. Two hundred and forty 1-d-old chicks (Avian-43) were randomly divided into three dietary treatment groups and fed with the following diets: (i) basal diet (control) (BD); (ii) basal diet with parental Lactobacillus strains (BDP) and (iii) basal diet with transformed Lactobacillus strains (BDT). At 21 d of age, the body weight, body weight gain and feed conversion ratio of the BDT-fed chickens were significantly improved. At 14 and 21 d of age, the proportions of dry matter in the duodenum, jejunum, ileum, caeca and excreta of chickens given the BDT diet were significantly higher than those of chickens given the BD and BDP diets. Apparent metabolisable energy, digestibilities of crude protein and dry matter were also significantly improved (by 3.5, 5.6 and 3.5%, respectively) by the BDT diet. These results showed that the transformed Lactobacillus strains improved digestibility as well as enhanced the growth performance of chickens.

Influence of beta-glucanase-producing Lactobacillus strains on intestinal characteristics and feed passage rate of broiler chickens.

Two experiments were conducted to study the effects of beta-glucanase produced by transformed Lactobacillus strains on the intestinal characteristics and feed passage rate of broiler chickens fed barley-based diets. Supplementation of transformed Lactobacillus strains to the diet of chickens significantly (P < 0.05) reduced the intestinal fluid viscosity by 21 to 46% compared with chickens fed an unsupplemented diet or a diet supplemented with parental Lactobacillus strains. The relative weights of pancreas, liver, duodenum, jejunum, ileum, ceca, and colon were reduced (P < 0.05) by 6 to 27%, and the relative length of duodenum, jejunum, ileum, and ceca was reduced (P < 0.05) by 8 to 15%. Histological examination of the intestinal tissues showed that the jejunal villus height of chickens fed a diet supplemented with transformed Lactobacillus strains was significantly (P < 0.05) higher than that of chickens fed other dietary treatments. The transformed Lactobacillus strains were found to reduce (P < 0.05) the time of feed passage rate by 2.2 h. Supplementation of transformed Lactobacillus strains to the diet improved the intestinal characteristics and feed, passage rate of the chickens.