Bacillus and Brevibacillus strains as potential antagonists of Paenibacillus larvae and Ascosphaera apis

Laura Cecilia Bartel, Eliana Abrahamovich, Consuelo Mori, Ana Claudia López, Adriana Mónica Alippi
2018 Journal of Apicultural Research  
Species of Bacillus and Brevibacillus associated with honey bees are interesting sources of bioactive compounds with potential uses beyond the field of apiculture. Most Bacillus species and related genera produce a broad range of antimicrobial compounds, with activity against bacteria and fungi that include peptides, lipopeptides, bacteriocins, and bacteriocin-like inhibitory substances. By using biological tools, we evaluated the antagonistic activity of 34 bacterial strains against
more » ... us larvae and Ascosphaera apis, the causal agents of American Foulbrood and Chalkbrood diseases of honey bee larvae, respectively. Data reveal that the antagonistic response was strain-specific, species-specific, and also medium-dependent. By using molecular tools, we investigated the distribution of antimicrobial peptide genes in the antagonist strains. The presence of homologous sequences to nine genes encoding for the synthesis of the antimicrobial peptides bacillomycin L (bmyB), fengycin (fenD), bacilysin (bacA), subtilin (spaS), iturin A (ituD, lpa-14; ituC), and surfactin (sfp; srfAA) was assayed by PCR. The distribution and frequency of these genes within the bacterial antagonists were also variable and strain-dependent, being the most common surfactins (srfAA ¼ 44% and lpa-14 ¼ 38%), iturins (ituD ¼ 47%), and bacilysin (bacA ¼ 32%). Moreover, a positive correlation between presence of antimicrobial peptide genes and antagonism was found taking into account that 85% of the antagonists had at least one of the antimicrobial peptide genes. We also identified those antagonists active against different P. larvae genotypes. To our knowledge, this is the first study of the association between the presence of homologous sequences of antimicrobial peptide genes and antagonism against P. larvae and A. apis strains. Cepas de Bacillus and Brevibacillus como antagonistas potenciales de Paenibacillus larvae y Ascosphaera apis. Las especies de Bacillus y Brevibacillus asociadas con abejas mel ıferas son una fuente interesante de compuestos bioactivos con usos potenciales m as all a del campo de la apicultura. La mayor ıa de las especies de Bacillus producen una amplia gama de compuestos antimicrobianos, con actividad contra bacterias y hongos que incluye p eptidos, lipop eptidos, bacteriocinas y sustancias inhibidoras similares a bacteriocinas (BLIS). Con el objeto de buscar alternativas naturales para el control de loque americana y cr ıa yesificada, se emplearon herramientas biol ogicas para evaluar la actividad antag onica de 34 cepas bacterianas contra cepas de Paenibacillus larvae y de Ascosphaera apis, agentes causales de estas enfermedades. Los resultados obtenidos mostraron que la respuesta antag onica fue medio-dependiente y cepa-dependiente. Se analiz o por PCR la presencia de secuencias hom ologas a 9 genes relacionados con la s ıntesis de p eptidos antimicrobianos: bacilomicina L (bmyB), fengicina (fenD), bacilicina (bacA), subtilina (spaS), iturina A (ituD, lpa-14; ituC), y surfactina (sfp; srfAA). La distribuci on y frecuencia de estos genes en las cepas antagonistas tambi en result o variable y cepa-dependiente, siendo los m as comunes surfactinas (srfAA ¼ 44% y lpa-14 ¼ 38%), iturina A (ituD ¼ 47%) y bacilicina (bacA ¼ 32%). Se identificaron antagonistas bacterianos frente a distintos genotipos de P. larvae y se encontr o una correlaci on positiva entre la presencia de genes vinculados con la producci on de p eptidos antimicrobianos y la inhibici on del desarrollo de P. larvae. Este trabajo constituye el primer estudio de asociaciones entre presencia de estos genes y el antagonismo frente a P. larvae y A. apis.
doi:10.1080/00218839.2018.1495439 fatcat:6fioaikvizhlrkv6mswgtpj2yy