Bacillus strains as feed additives: In vitro evaluation of its potential probiotic properties Bacilos utilizados como aditivos para piensos: Evaluación in vitro de sus potenciales propiedades probióticas Bacilos utilizados como aditivos para concentrados: Avalia o in vitro de suas propriedades probióticas

Background: much recent attention has been devoted to the genuine value of Bacillus species as multifunctional probiotic products, which produce various extracellular enzymes that enhance feed digestibility as well as many antimicrobial compounds for the purpose of improving animal performance. Objective: to describe novel, in vitro potential probiotic properties such as acid tolerance, bile tolerance, safety, and antimicrobial activity of mesophilic and psychrophilic Bacillus strains in conjunction with their extracellular enzymatic activities. Methods: four Bacillus strains (B. sp. T3, B. sp. T4, B. sp. SM2, and B. sp. JSP1) isolated from different sources were used. Strains were identified according to 16S rDNA sequences. Escherichia coli K88, E. coli O157:H7, Salmonella enteritidis KCCM 12021, Enterococcus faecalis, Listeria monocytogenes, and Staphylococcus aureus were used as indicator bacteria for the antimicrobial activity trial. Strains were activated and cultured in tryptic soy broth (pH 7.0) or broth solidified with 1.5% agar. Results: B. sp. JSP1 was fully resistant to both pH 2 and 3, whereas B. sp. SM2 showed relatively good viability at pH 3. All strains tolerated oxgall (0.3%) bile salt and were not cytotoxic to the HEK 293 human embryonic kidney cells. Three strains, except B. sp. T3, displayed differential production of extracellular enzymes including amylase, xylanase, cellulase, protease, phytase, and α-galactosidase. In particular, B. sp. SM2 inhibited six indicator pathogens: Escherichia coli K88, E. coli O157:H7, Salmonella enteritidis, Enterococcus faecalis, Listeria monocytogenes, and Staphylococcus aureus. Conclusion: the single use of B. sp. SM2 or the mixed use of the strain combined with acid or bile tolerant Bacillus strains secreting extracellular enzymes may be an alternative to antibiotics as a feed additive in farm animal production. Antecedentes: recientemente el valor de las especies de Bacillus como productos probióticos multifuncionales ha recibido bastante atención, debido a que estos producen varias enzimas extracelulares que potencian la digestibilidad de los alimentos, así como también compuestos antimicrobianos que mejoran el desempe o del animal. Objetivo: describir y evaluar potenciales propiedades probióticas ''in vitro'' -tales como acidez, tolerancia a la bilis, seguridad y actividad antimicrobiana- de cuatro cepas de Bacilos (B. sp. T3, B. sp. T4, B. sp. SM2 y B. sp. JSP1) aisladas de diferentes fuentes, en conjunción con sus actividades enzimáticas extracelulares. Métodos: se usaron cuatro cepas de Bacill