title: Selection of Bacillus spp. for Cellulase and Xylanase Production as Direct-Fed Microbials to Reduce Digesta Viscosity and Clostridium perfringens Proliferation Using an in vitro Digestive Model in Different Poultry Diets.
abstract: Previously, our laboratory has screened and identified Bacillus spp. isolates as direct-fed microbials (DFM). The purpose of the present study was to evaluate the cellulase and xylanase production of these isolates and select the most appropriate Bacillus spp. candidates for DFM. Furthermore, an in vitro digestive model, simulating different compartments of the gastrointestinal tract, was used to determine the effect of these selected candidates on digesta viscosity and Clostridium perfringens proliferation in different poultry diets. Production of cellulase and xylanase were based on their relative enzyme activity. Analysis of 16S rRNA sequence classified two strains as Bacillus amyloliquefaciens and one of the strains as Bacillus subtilis. The DFM was included at a concentration of 10(8) spores/g of feed in five different sterile soybean-based diets containing corn, wheat, rye, barley, or oat. After digestion time, supernatants from different diets were collected to measure viscosity, and C. perfringens proliferation. Additionally, from each in vitro simulated compartment, samples were taken to enumerate viable Bacillus spores using a plate count method after heat-treatment. Significant (P < 0.05) DFM-associated reductions in supernatant viscosity and C. perfringens proliferation were observed for all non-corn diets. These results suggest that antinutritional factors, such as non-starch polysaccharides from different cereals, can enhance viscosity and C. perfringens growth. Remarkably, dietary inclusion of the DFM that produce cellulase and xylanase reduced both viscosity and C. perfringens proliferation compared with control diets. Regardless of diet composition, 90% of the DFM spores germinated during the first 30 min in the crop compartment of the digestion model, followed by a noteworthy increased in the intestine compartment by ~2log10, suggesting a full-life cycle development. Further studies to evaluate in vivo necrotic enteritis effects are in progress.
authors.affiliation: Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
authors.forename: Juan D
authors.initials: JD
authors.lastname: Latorre
authors.affiliation: Departamento de Medicina y Zootecnia de Aves, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autonoma de Mexico , Mexico City , Mexico.
authors.forename: Xochitl
authors.initials: X
authors.lastname: Hernandez-Velasco
authors.affiliation: Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
authors.forename: Vivek A
authors.initials: VA
authors.lastname: Kuttappan
authors.affiliation: Pacific Vet Group-USA, Inc. , Fayetteville, AR , USA.
authors.forename: Ross E
authors.initials: RE
authors.lastname: Wolfenden
authors.affiliation: Pacific Vet Group-USA, Inc. , Fayetteville, AR , USA.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Vicente
authors.affiliation: Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
authors.forename: Amanda D
authors.initials: AD
authors.lastname: Wolfenden
authors.affiliation: Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
authors.forename: Lisa R
authors.initials: LR
authors.lastname: Bielke
authors.affiliation: Facultad de Medicina Veterinaria y Zootecnia, Universidad de Colima , Colima , Mexico.
authors.forename: Omar F
authors.initials: OF
authors.lastname: Prado-Rebolledo
authors.affiliation: Departamento de Produccion Agricola y Animal, Universidad Autonoma Metropolitana , Mexico City , Mexico.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Morales
authors.affiliation: Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
authors.forename: Billy M
authors.initials: BM
authors.lastname: Hargis
authors.affiliation: Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Tellez
keywords: Bacillus-DFM; Clostridium perfringens; enzymes; spore; viscosity