Lactobacillus flora in the cloaca and vagina of hens and its inhibitory activity against Salmonella enteritidis in vitro

Modulatory Effects of Bacillus subtilis on the Performance, Morphology, Cecal Microbiota and Gut Barrier Function of Laying Hens

We investigated the efficacy of a single bacterium strain, Bacillus subtilis (B. subtilis) YW1, on the performance, morphology, cecal microbiota, and intestinal barrier function of laying hens. A total of 216 28-week-old Hy-line Brown laying hens were divided into three dietary treatment groups, with six replicates of 12 birds each for 4 weeks. The control group (Ctr) was fed a basal diet and the treatment groups, T1 and T2, were fed a basal diet supplemented with B. subtilis at a dose rate of 5 × 108 CFU/kg and 2.5 × 109 CFU/kg, respectively. Dietary supplementation with B. subtilis did not significantly affect overall egg production in both groups, with no obvious changes in average egg weight and intestine morphology. B. subtilis administration also improved the physical barrier function of the intestine by inducing significantly greater expression levels of the tight junction protein occludin in T1 (p = 0.07) and T2 (p < 0.05). Further, supplementation with B. subtilis effectively modulated the cecal microbiota, increasing the relative level of beneficial bacteria at the genus level (e.g., Bifidobacterium p < 0.05, Lactobacillus p = 0.298, Bacillus p = 0.550) and decreasing the level of potential pathogens (e.g., Fusobacterium p < 0.05, Staphylococcus p < 0.05, Campylobacter p = 0.298). Overall, B. subtilis YW1 supplementation cannot significantly improve the egg production; however, it modulated the cecal microbiota towards a healthier pattern and promoted the mRNA expression of the tight junction protein occludin in laying hens, making B. subtilis YW1 a good probiotic candidate for application in the poultry industry, and further expanding the resources of strains of animal probiotics.

Characteristics of the fecal microbiota of high- and low-yield hens and effects of fecal microbiota transplantation on egg production performance

The microbiota that resides in the digestive tract plays pivotal role in maintaining intestinal environmental stability by promoting nutrition digestion and intestinal mucosal immunity. However, whether the intestinal microbiota in laying hens affects egg laying- performance is not known. In this study, 16S rDNA gene sequencing and fecal microbiota transplantation were used to determine the structure of the intestinal microbiota and the effect of the intestinal microbiota on egg production. The results revealed that Firmicutes were dominant in both the H (high egg laying rates) and L (low egg laying rates) groups, while Bacteroides, Actinobacteria and Proteobacteria were significantly enriched in the L group compared to the H group. The laying rates were weakly affected in H hens transplanted with the fecal microbiota from L hens, except for temporary fluctuation, while the egg laying rates were significantly increased in L hens transplanted with the fecal microbiota from H hens. Therefore, we concluded that the population structure of the intestinal microbiota varied between the H and L groups, and the intestinal microbiota of high-yield laying hens had significant effects on low-yield laying hens performance.

Avaliação in vitro da atividade inibitória de Lactobacillus spp., isolados do inglúvio e cecos de aves sobre Salmonella

Inglúvios e cecos de reprodutoras comerciais de frangos de corte foram utilizados para o isolamento de Lactobacillus spp. As estirpes isoladas foram caracterizadas como Gram-positivo, catalase negativo, produtoras de gás em glicose, não produtoras de H2S em triple sugar iron e identificadas pela reação em cadeia da polimerase como Lactobacillus reuteri e Lactobacillus salivarius. A utilização da técnica spot-on-the-lawn para avaliação da inibição in vitro permitiu a análise de vários microrganismos simultaneamente. Todas as estirpes isoladas inibiram in vitro S. Enteritidis fagotipo 4, S. Enteritidis fagotipo 28, S. Typhimurium, S. Pullorum, S. Agona, S. Anatum, S. Dublin e S. Senftenberg.

Identification of lactobacilli isolated from the cloaca and vagina of laying hens and characterization for potential use as probiotics to control Salmonella Enteritidis

AIMS

To select Lactobacillus strains from laying hens for potential use as probiotic to control Salmonella Enteritidis infection.

METHODS AND RESULTS

One hundred and eighty-six lactobacilli were isolated from the cloaca and vagina of laying hens, and identified at the species level by a polyphasic taxonomic approach. All isolates belonged to the Lactobacillus acidophilus, Lactobacillus reuteri or Lactobacillus salivarius phylogenetic groups, with the L. reuteri group being the most predominant group. Based on genetic diversity, about 50 representative strains were selected and tested for in vitro properties that could be predictive for probiotic activity in laying hens. Salmonella inhibition was shown to be species dependent, and correlated to some extent with the production of lactic acid. A selection of strains was evaluated in a S. Enteritidis challenge experiment. Two strains, L. reuteri R-17485 and Lactobacillus johnsonii R-17504 significantly decreased the colonization of chicks by S. Enteritidis in caeca, liver and spleen.

CONCLUSIONS

Lactobacilli isolated from laying hens were observed to inhibit Salmonella growth in vitro, most probably through production of lactic acid, and to decrease in vivo the S. Enteritidis colonization of chicks.

SIGNIFICANCE AND IMPACT OF THE STUDY

The data demonstrate that Lactobacillus isolates from laying hens may have probiotic potential in reducing S. Enteritidis infection.

Ability of Bacteriophages Isolated from Different Sources to Reduce Salmonella enterica Serovar Enteritidis In Vitro and In Vivo

Salmonella enterica serovar Enteritidis-lysing bacteriophages isolated from poultry or human sewage sources were used to reduce Salmonella Enteritidis in vitro and in experimentally infected chicks. Cocktails of 4 different bacteriophages obtained from commercial broiler houses (CB4Ø) and 45 bacteriophages from a municipal wastewater treatment plant (WT45Ø) were evaluated. In experiment 1, an in vitro crop assay was conducted with selected bacteriophage concentrations (10(5) to 10(9) pfu/mL) to determine ability to reduce Salmonella Enteritidis in the simulated crop environment. Following 2 h at 37 degrees C, CB4Ø or WT45Ø reduced Salmonella Enteritidis recovery by 1.5 or 5 log, respectively, as compared with control. However, CB4Ø did not affect total SE recovery after 6 h, whereas WT45Ø resulted in up to a 6-log reduction of Salmonella Enteritidis. In experiment 2, day-of-hatch chicks were challenged orally with 3 x 10(3) cfu/chick Salmonella Enteritidis and treated cloacally with 1 x 10(9) WT45Ø pfu/chick 1 h postchallenge. One hour later, chicks were treated or not with a commercially available probiotic (Floramax-B11). Both treatments significantly reduced Salmonella Enteritidis recovery from cecal tonsils at 24 h following vent lip application as compared with controls, but no additive effect was observed with the combination of bacteriophages and probiotic. In experiment 3, day-of-hatch chicks were challenged orally with 9 x 10(3) cfu/chick Salmonella Enteritidis and treated via oral gavage with 1 x 10(8) CB4Ø pfu/chick, 1.2 x 10(8) WT45Ø pfu/chick, or a combination of both, 1 h postchallenge. All treatments significantly reduced Salmonella Enteritidis recovered from cecal tonsils at 24 h as compared with untreated controls, but no significant differences were observed at 48 h following treatment. These data suggest that some bacteriophages can be efficacious in reducing SE colonization in poultry during a short period, but with the bacteriophages and methods presently tested, persistent reductions were not observed.

Salmonellae reduction in poultry by competitive exclusion bacteria Lactobacillus salivarius and Streptococcus cristatus

The objective of this study was to develop a defined competitive exclusion bacteria (CE) culture that will prevent or substantially reduce Salmonella colonization of poultry. The efficacy of 56 potential CE isolates in preventing or reducing Salmonella colonization in chickens was determined. These potential CE were perorally administered to day-of-hatch chicks at 10(6) to 10(8) CFU per chick, and salmonellae were subsequently administered by gavage 2 days later at 5.5 x 10(3) to 5.0 x 10(4) CFU per chick. Feeding chickens an overnight CE culture of Lactobacillus salivarius strains Salm-9, List40-1,8, or List40-41 reduced Salmonella carriage in cecal contents by 2.10, 2.52, and 2.20 log CFU/g (average of three trials), respectively. The percentages of Salmonella-positive chickens after receiving these treatments were 35, 31, and 35% respectively, compared with 84% for the untreated control. A mixture of these three isolates had a similar effect when compared with the results of the individual isolates. A mixture of Streptococcus cristatus List40-13 and L. salivarius List40-41 reduced Salmonella carriage from 90 to 65% and 88 to 31% in two feeding trials, and by 2.2 and 4 log CFU/g of cecal contents of chickens. In conclusion, CE isolates L. salivarius Salm-9, List40-18, and List40-41 and S. cristatus List40-13 either individually or in combination were effective in significantly preventing Salmonella colonization of chickens.

Potential competitive exclusion bacteria from poultry inhibitory to Campylobacter jejuni and Salmonella

The objective of this study was to isolate from chickens potential competitive exclusion bacteria (CE) that are inhibitory to Campylobacter jejuni or Salmonella, or to both, for subsequent development of a defined CE product for use in poultry. Adult chickens from family farms, commercial farms, and broiler chicken research centers were sampled to identify and select C. jejuni-free donor chickens. A challenge treatment, which included administering perorally 106 CFU C. jejuni per chicken and determining undetectable cecal shedding of campylobacters at 4 weeks, was important for identifying the best CE donor chickens. Screening of bacterial colonies obtained from nine donor chickens by using selective and nonselective media yielded 636 isolates inhibitory to six C. jejuni strains in vitro, with 194 isolates being strongly inhibitory. Of the 194 isolates, 145 were from ceca, and 117 were facultative anaerobic bacteria. One hundred forty-three isolates were inhibitory to six strains of Salmonella (including five different serotypes) in vitro. Of these, 41 were strongly inhibitory to all C. jejuni and Salmonella strains evaluated, and most were Lactobacillus salivarius. A direct overlay method, which involved directly applying soft agar on plates with discrete colonies from mucus scrapings of gastrointestinal tracts, was more effective in isolating CE than was the frequently practiced isolation method of picking and transferring discrete colonies and then overlaying them with soft agar. The best approach for obtaining bacteria highly inhibitory to Salmonella and C. jejuni from chickens was to isolate bacteria from ceca under anaerobic conditions. Free-range chickens from family farms were better donors of potential CE strongly inhibitory to both Salmonella and Campylobacter than were chickens from commercial farms and broiler chicken research centers.

Surgical site abscess caused by Lactobacillus fermentum identified by 16S ribosomal RNA gene sequencing

We report the first case of surgical site abscess caused by Lactobacillus fermentum from a 53-year-old woman with squamous cell carcinoma of the esophagus after transthoracic esophagectomy and neoadjuvant chemoirradiation. 16S rRNA gene sequencing is a useful tool to better characterize the epidemiology and clinical significance of L. fermentum.

Development and assessment of a real-time pcr assay for rapid and sensitive detection of a novel thermotolerant bacterium, Lactobacillus thermotolerans, in chicken feces

A new real-time PCR assay was successfully developed using a TaqMan fluorescence probe for specific detection and enumeration of a novel bacterium, Lactobacillus thermotolerans, in chicken feces. The specific primers and probe were designed based on the L. thermotolerans 16S rRNA gene sequences, and these sequences were compared to those of all available 16S rRNA genes in the GenBank database. The assay, targeting 16S rRNA gene, was evaluated using DNA from a pure culture of L. thermotolerans, DNA from the closely related bacteria Lactobacillus mucosae DSM 13345(T) and Lactobacillus fermentum JCM 1173(T), and DNA from other lactic acid bacteria in quantitative experiments. Serial dilutions of L. thermotolerans DNA were used as external standards for calibration. The minimum detection limit of this technique was 1.84 x 10(3) cells/ml of an L. thermotolerans pure culture. The assay was then applied to chicken feces in two different trials. In the first trial, the cell population was 10(4) cells/g feces on day 4 and 10(5) cells/g feces on days 11 to 18. However, cell populations of 10(6) to 10(7) cells/g feces were detected in the second trial. The total bacterial count, measured by 4',6-diamidino-2-phenylindole (DAPI) staining, was approximately 10(11) cells/g feces. These results suggest that in general, L. thermotolerans is a normal member of the chicken gut microbiota, although it is present at relatively low levels in the feces.

Identification of Lactobacillus crispatus by polymerase chain reaction targeting S-layer protein gene

AIMS

This study aimed to develop a polymerase chain reaction (PCR) method to identify Lactobacillus crispatus.

METHODS AND RESULTS

A primer set (CbsA2F-CbsA2R) for amplifying conserved regions of S-layer genes was designed to identify Lact. crispatus and the specificity of this set was compared with that of another primer set (Cri 16SI-Cri 16SII) which has been reported as a species-specific primer set targeting the 16S rRNA gene. Among species in the Lact. acidophilus A1-A4 groups, when KOD polymerase was used for amplification, the primer set CbsA2F-CbsA2R gave PCR products with Lact. crispatus strains only. However, when Taq polymerase was used, this primer set gave products with one Lact. amylovorus strain as well as with Lact. crispatus strains. The primer set Cri 16SI-Cri 16SII gave PCR products with Lact. crispatus strains and two Lact. acidophilus strains, regardless of whether the polymerase used was KOD or Taq.

CONCLUSIONS

A PCR targeting the S-layer gene and amplified with KOD polymerase can identify Lact. crispatus accurately and rapidly.

SIGNIFICANCE AND IMPACT OF THE STUDY

To the authors' knowledge, this is the first paper to provide a PCR method for the specific identification of Lact. crispatus.