Effects of physical culture parameters on bacteriocin production by Mexican strains of Bacillus thuringiensis after cellular induction |
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Authors: | Janeth Adriana Martínez-Cardeñas Norma M de la Fuente-Salcido Rubén Salcedo-Hernández Dennis K Bideshi J Eleazar Barboza-Corona |
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Institution: | 1. División Ciencias de la Vida, Departamento de Alimentos, Universidad de Guanajuato, Campus Irapuato-Salamanca, Apartado Postal 311, 36500, Irapuato, Guanajuato, Mexico 2. Escuela de Ciencias Biológicas, Universidad Autónoma de Coahuila, 27440, Torreón, Coahuila, Mexico 3. Department of Natural and Mathematical Sciences, California Baptist University, 8432 Magnolia Avenue, Riverside, CA, 92504, USA 4. Department of Entomology, University of California, Riverside, Riverside, CA, 92521, USA
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Abstract: | We have shown previously that in the presence of inducer Bacillus cereus 183, significant increases in bacteriocin production and bactericidal activity of B. thuringiensis occur when the latter is cultivated at pH 7.2, 28°C, and 180 rpm. Here we show that this activity can be further improved
when B. thuringiensis is induced with B. cereus 183 and then cultivated with modification of pH, temperature, and agitation. Five native strains of B. thuringiensis, LBIT 269, LBIT 287, LBIT 404, LBIT 420, and LBIT 524 which synthesize, respectively, morricin 269, kurstacin 287, kenyacin
404, entomocin 420, and tolworthcin 524, were cultivated in four different fermentation media. Of these, fermentation in tryptic
soy broth (TSB) yielded the highest level of bacteriocin activity (~100–133 FU). Bacteria grown in TSB were induced with B. cereus 183 and cultivated at different pH (6.0, 7.2, 8.0), temperature (26, 28, 30°C), and agitation (150, 180, 210 rpm). Full factorial
design was performed and results were analyzed with analysis of variance (ANOVA) and Tukey multiple comparison tests at significant
level of α ≤ 0.05 to study the influence of the three variables on bacterial growth and bacteriocin production. Our data show that the
highest bacteriocin activity was found with LBIT 269 and LBIT 404 with an increase of ~95–100% compared with induced B. thuringiensis strains cultivated under fixed conditions (pH 7.2, 28°C, 180 rpm), for which the data were set at 0%. The optimal conditions
for morricin 269 and kenyacin 404 production were, respectively, pH 8, 30°C, 210 rpm and pH 7.2, 26°C, 210 rpm. |
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