Evaluation and Selection ofBacillusSpecies Based on Enzyme Production, Antimicrobial Activity, and Biofilm Synthesis as Direct-Fed Microbial Candidates for Poultry.
Social concern about misuse of antibiotics as growth promoters (AGP) and generation of multidrug-resistant bacteria have restricted the dietary inclusion of antibiotics in livestock feed in several countries. Direct-fed microbials (DFM) are one of the multiple alternatives commonly evaluated as substitutes of AGP. Sporeformer bacteria from the genusBacillushave been extensively investigated because of their extraordinary properties to form highly resistant endospores, produce antimicrobial compounds, and synthesize different exogenous enzymes. The purpose of the present study was to evaluate and selectBacillusspp. from environmental and poultry sources as DFM candidates, considering their enzyme production profile, biofilm synthesis capacity, and pathogen-inhibition activity. Thirty-oneBacillusisolates were screened forin vitrorelative enzyme activity of amylase, protease, lipase, and phytase using a selective media for each enzyme, with 3/31 strains selected as superior enzyme producers. These three isolates were identified asBacillus subtilis(1/3), andBacillus amyloliquefaciens(2/3), based on biochemical tests and 16S rRNA sequence analysis. For evaluation of biofilm synthesis, the generation of an adherent crystal violet-stained ring was determined in polypropylene tubes, resulting in 11/31 strains showing a strong biofilm formation. Moreover, allBacillusstrains were evaluated for growth inhibition activity againstSalmonella entericaserovar Enteritidis (26/31),Escherichia coli(28/31), andClostridioides difficile(29/31). Additionally, in previousin vitroandin vivostudies, these selectedBacillusstrains have shown to be resistant to different biochemical conditions of the gastrointestinal tract of poultry. Results of the present study suggest that the selection and consumption ofBacillus-DFM, producing a variable set of enzymes and antimicrobial compounds, may contribute to enhanced performance through improving nutrient digestibility, reducing intestinal viscosity, maintaining a beneficial gut microbiota, and promoting healthy intestinal integrity in poultry.
Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
Juan D
JD
Latorre
Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México , Ciudad de México , México.
Xochitl
X
Hernandez-Velasco
Pacific Vet Group-USA, Inc. , Fayetteville, AR , USA.
Ross E
RE
Wolfenden
Pacific Vet Group-USA, Inc. , Fayetteville, AR , USA.
Jose L
JL
Vicente
Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
Amanda D
AD
Wolfenden
Pacific Vet Group-USA, Inc. , Fayetteville, AR , USA.
Anita
A
Menconi
Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
Lisa R
LR
Bielke
Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
Billy M
BM
Hargis
Department of Poultry Science, University of Arkansas , Fayetteville, AR , USA.
Guillermo
G
Tellez
Bacillus; antimicrobial; biofilm; direct-fed microbial; enzyme