RESUMO
Mastitis caused by microbial infections in dairy goats reduces milk yield, modifies milk composition, and potentially contributes to morbidity in herds and consumers of dairy products. Microorganisms associated with mastitis in dairy goats are commonly controlled with antibiotics, but it is known that continued use of these chemical agents promotes antibiotic resistance among bacterial populations. Recently, it has been shown that bacteriocins of Bacillus thuringiensis inhibit growth of food-borne pathogens and also bacteria associated with bovine mastitis. However, there is no report on their ability to inhibit microorganisms linked to mastitis in dairy goats. In this study, using 16S rDNA and ITS regions of rDNA, we identified nine bacterial isolates and an encapsulated yeast associated with mastitis in dairy goats. Enterococcus durans, Brevibacillus sp., and Staphylococcus epidermidis 2 were resistant to, respectively, 75, ~67, ~42, and ~42 % of the antibiotics screened. In addition, 60 % of the bacterial isolates were resistant to penicillin, ampicillin, vancomycin, and dicloxacillin. Importantly, 60 % of the isolates were inhibited by the bacteriocins, but S. epidermidis 1, Enterobacter sp., Escherichia vulneris, and Cryptococcus neoformans were not susceptible to these antimicrobial peptides. Using Brevibacillus sp. and Staphylococcus chromogenes as indicator bacteria, we show that peptides of ~10 kDa that correspond to the molecular mass of bacteriocins used in this study are responsible for the inhibitory activity. Our results demonstrate that multiple antibiotic-resistant bacteria associated with subclinical mastitis in dairy goats from Guanajuato, Mexico, are susceptible to bacteriocins produced by B. thuringiensis.
Assuntos
Bacillus thuringiensis/química , Infecções Bacterianas/veterinária , Bacteriocinas/farmacologia , Mastite/veterinária , Micoses/veterinária , Animais , Infecções Bacterianas/tratamento farmacológico , Infecções Bacterianas/microbiologia , Bacteriocinas/isolamento & purificação , Bacteriocinas/uso terapêutico , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Fúngico/química , DNA Fúngico/genética , DNA Ribossômico/química , DNA Ribossômico/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Doenças das Cabras/tratamento farmacológico , Doenças das Cabras/microbiologia , Cabras , Mastite/tratamento farmacológico , Mastite/microbiologia , México , Testes de Sensibilidade Microbiana , Micoses/tratamento farmacológico , Micoses/microbiologia , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
Although several strains of B. subtilis with antifungal activity have been isolated worldwide, to date there are no published reports regarding the isolation of a native B. subtilis strain from strawberry plants in Mexico. A native bacterium (Bacillus subtilis 21) demonstrated in vitro antagonistic activity against different plant pathogenic fungi. Under greenhouse conditions, it was shown that plants infected with Rhizoctonia solani and Fusarium verticillioides and treated with B. subtilis 21 produced augment in the number of leaves per plant and an increment in the length of healthy leaves in comparison with untreated plants. In addition, B. subtilis 21 showed activity against pathogenic bacteria. Secreted proteins by B. subtilis 21 were studied, detecting the presence of proteases and bacteriocin-like inhibitor substances that could be implicated in its antagonistic activity. Chitinases and zwittermicin production could not be detected. Then, B. subtilis 21 could potentially be used to control phytopathogenic fungi that infect strawberry plants.
Assuntos
Antibiose/fisiologia , Bacillus subtilis/fisiologia , Bactérias/crescimento & desenvolvimento , Fungos/crescimento & desenvolvimento , Bacillus subtilis/isolamento & purificação , Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Bacteriocinas/metabolismo , Fragaria/microbiologia , Fusarium/crescimento & desenvolvimento , Bactérias Gram-Negativas/crescimento & desenvolvimento , Bactérias Gram-Positivas/crescimento & desenvolvimento , México , Peptídeo Hidrolases/metabolismo , Peptídeos/genética , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Reação em Cadeia da Polimerase , Rhizoctonia/crescimento & desenvolvimentoRESUMO
Recently, we reported the synthesis of five bacteriocin-like inhibitor substances (Bt-BLIS: morricin 269, kurstacin 287, kenyacin 404, entomocin 420, and tolworthcin 524) by Mexican strains of Bacillus thuringiensis. Here we show that, collectively, these Bt-BLIS have a moderate to broad spectrum of antibacterial activity, being toxic to clinically significant against Gram-positive and Gram-negative bacteria, including common etiological agents of human diseases, such as strep throat and scarlet fever, septicemia, pneumonia, urinary tract infection, and emetic and gastrointestinal syndromes. Although synthesis of the five Bt-BLIS was independent of the presence of a target inducing bacterium, we demonstrated for the first time that a proteinaceous component(s) secreted by, or liberated by proteolytic cleavage of Bacillus cereus 183 following treatment with proteinase K, enhanced Bt-BLIS synthesis.