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 108 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.

Effect of humic acids on intestinal viscosity, leaky gut and ammonia excretion in a 24 hr feed restriction model to induce intestinal permeability in broiler chickens

“…The in vitro digestion model was performed in quintuplicate at 40°C to simulate poultry body temperature according to previous publications with minor modifications (Annett et al., ; Latorre et al., ). In this experiment, two diets were tested: a control non‐treated diet (Table ) and a control diet supplemented with 6% HA.…”

Comparison of PrestoBlue® and plating method to evaluate antimicrobial activity of ascorbic acid, boric acid and curcumin in an in vitro gastrointestinal model

“…The in vitro digestion model used in this study was based on previous publications, with minor modifications (Annett et al 2002;Latorre et al 2015), and the assay was performed with one control and 18 different treatments by triplicate. Briefly, for all the gastrointestinal compartments simulated during the in vitro digestion model, a biochemical oxygen demand incubator (VWR, Houston, TX) set at 40°C (to simulate poultry body temperature), customized with a standard orbital shaker (19 rpm; VWR) was used for mixing the feed content.…”

Dietary Factors as Triggers of Low-Grade Chronic Intestinal Inflammation in Poultry

“…Therefore, if these ingredients are used in poultry feed, especially for broilers, the effects of soluble fiber should be considered as a trigger of inflammation. Although some practices can be used to avoid the negative effects of a diet with a higher NSP content, as feed probiotics that produce phytase, lipase, xylanase and cellulases [51] add insoluble fiber to the feed and supplementation of exogenous enzymes capable of breaking NSP, such as xylanase and β-glucanase [40].…”