Potential use of Bacillus thuringiensis bacteriocins to control antibiotic-resistant bacteria associated with mastitis in dairy goats

publicaciones

A. J. Gutiérrez-Chávez 1,3; E. A. Martínez-Ortega1; M. Valencia-Posadas1,3; M. F. León-Galván2,3; N. M. de la Fuente-Salcido4; D. K. Bideshi5,6; J. E. Barboza-Corona2,3

1 Departamento de Agronomía, División de Ciencias de la Vida, Universidad de Guanajuato Campus Irapuato-Salamanca, Guanajuato 36500, Mexico
2 Departamento de Alimentos, División de Ciencias de la Vida, Universidad de Guanajuato Campus Irapuato-Salamanca, Guanajuato 36500, Mexico
3 Posgrado en Biociencias Irapuato, División de Ciencias de la Vida, Universidad de Guanajuato Campus Irapuato-Salamanca, Guanajuato 36500, Mexico
4 Escuela de Ciencias Biológicas, Aniversidad Autónoma de Coahuila, Torreón, Coahuila 27104, Mexico
5 Department of Natural and Mathematical Sciences, California Baptist University, 8432 Magnolia Avenue, Riverside, CA 92504, USA
6 Department of Entomology, University of California, Riverside, Riverside, CA 92521, USA

*josebar@ugto.mx

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.

Norma3-2016


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