Bacteriocin-like inhibitor substances produced by Mexican strains of Bacillus thuringiensis

Abstract

Bacteriocins are antimicrobial peptides synthesized and secreted by bacteria and could potentially be used as natural food preservatives. Here, we report the production of bacteriocin-like inhibitor substances (Bt-BLIS) by five Mexican strains of Bacillus thuringiensis. Bacillus thuringiensis subsp. morrisoni (LBIT 269), B. thuringiensis subsp. kurstaki (LBIT 287), B. thuringiensis subsp kenyae (LBIT 404), B. thuringiensis subsp. entomocidus (LBIT 420) and B. thuringiensis subsp. tolworthi (LBIT 524) produced proteinaceous Bt-BLIS with high levels of activity against Bacillus cereus and other gram-positive bacteria. Although none was active against the gram-negative bacteria, Escherichia coli, Shigella species and Pseudomonas aeruginosa, the five Bt-BLIS demonstrated antimicrobial activity against Vibrio cholerae, the etiologic agent of cholera. Biochemical and biophysical studies demonstrated that the five Bt-BLIS could be categorized into two groups, those produced by LBIT 269 and 287 (Group A) and LBIT 404, 420, 524 (Group B), based on relative time of peptide synthesis, distinctive bacterial target specificity and stability in a wide range of temperatures and pH. Because of their stability and bactericidal activities against B. cereus and V. cholerae agents of emetic, diarrheal and lethal syndromes in humans, these Bt-BLIS could potentially be used as biodegradable preservatives in the food industry.

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“…entomocidus (LBIT 420), and B. thuringiensis subsp. tolworthi (LBIT 524), where bactericidal activity was present in samples collected at middle of the logarithmic phase of growth and achieved the highest levels at the start of the stationary period Barboza-Corona et al [11]. The Bs21-BLIS activity against Staphylococcus aureus, Streptococcus pyogenes, and Enterobacter cloacae, potent agents of a number of community acquired and nosocomial diseases, including emesis, diarrhea, sore throat and scarlet fever, and urinary tract infections [27], suggests that these substances could be useful as a preservative in stored consumable products.…”

“…morrisoni (LBIT 269) and B. cereus 183 [11] (Figure 2); however a corresponding amplicon was not observed for B. subtilis 21.…”

“…morrisoni (LBIT 269) was obtained from a native bacterial stock collection held at CINVESTAV, Campus Guanajuato, Mexico. This strain synthesizes the bacteriocin called morricin 269 [11]. Bacillus cereus 183 was obtained from a collection of Bacillus strains maintained in the International Entomopathogenic Bacillus Centre, Institute Pasteur, Paris, France, and was employed as the indicator bacterium for determining, by a fluorogenic method, the time of the highest bacteriocin production by B. subtilis 21 [12] …”

“…morrisoni (LBIT 269) and B. cereus 183 were used as positive controls for zwittermycin gene amplification [11].…”

Screening and Characterization of Bacteriocin-Like Inhibitory Substances Produced by Bangladeshi Strains of Bacillus thuringiensis

“…This bacterium is well-known for its ability to produce crystal protein (Cry, a δ-endotoxin), which causes paralysis of the larval gut and cytolytic toxin (Cyt) (Aronson et al, 1986;Crickmore et al, 1998;Tounsi et al, 2003). As a result, most of the studies on B. thuringiensis have focused on its insecticidal activities and very little attention was given for other industrial products (Barboza-Corona et al, 2007). The main goal of the present study was to screen and characterize the novel bacteriocins from B. thuringiensis (Bt) isolated from different areas of Bangladesh (Asaduzzaman et al, 2012;Shishir et al, 2014).…”