Enhanced synthesis and antimicrobial activities of bacteriocins produced by Mexican strains of Bacillus thuringiensis

Abstract

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.

Future Challenges and Prospects of Bacillus thuringiensis

“…Nisin, a bacteriocin synthesized by Lactococcus lactis is currently the only bacteriocin with use in food industry and has been employed J. E. Barboza-Corona et al for the last two decades as a food preservative. It has been shown that bacteriocins of B. thuringiensis have a wide or narrow spectrum of activity against pathogenic bacteria (Cherif et al 2008;De la Fuente-Salcido et al 2008;Rea et al 2010). Both types of activity are important and could have different uses.…”

“…Both types of activity are important and could have different uses. For example, bacteriocins with wide activity could be used not only as antibiotics but also as biopreservatives in the control of food-borne pathogenic bacteria ; De la Fuente-Salcido et al 2008). Entomocin 110 and Thuricin 7 could be used respectively to control Listeria monocytogenes and preventing spoilage of raw milk and dairy products caused by B. weihenstephanensis (Cherif et al 2001(Cherif et al , 2008.…”

“…It was recently reported that the synthesis of five bacteriocins (Morricin 269, Kurstacin 287, Kenyacin 404, Entomocin 420, and Tolworthcin 524) from Mexican strains of B. thuringiensis is independent of the presence of a target inducing bacterium. However when the strains were co-cultured in presence of proteins synthesized and secreted or released by B. cereus, strains of B. thuringiensis increases the synthesis of the bacteriocins by quorum-sensing (De la Fuente-Salcido et al 2008). Additionally, an increment in the synthesis of the antimicrobial peptides has been obtained by modification of the culture physical conditions, as pH, temperature, aeration, in induced or non-induced bacteria (Kamoun et al 2009;Martínez-Cardeñas et al 2012), demonstrating that pH is probably the most important physical factor that affected not only growth of B. thuringiensis strains, but also bacteriocin production (Martínez-Cardeñas et al 2012 …”

Innovations in value-addition of edible meat by-products

“…One of the samples was used for monitoring cell growth spectrophotometrically at 600 nm, and the other was employed for bacteriocin detection using a rapid fluorogenic method [12], using B. cereus 183 as indicator bacterium. After determining the time that yielded the highest level of bacteriocin production, the bacterium was cultivated in fresh TSB and culture supernatant was concentrated with ammonium sulfate as described previously [12,13]. Precipitated proteins were pelleted by centrifugation at 16.000× g for 30 min at 4…”

“…Each point of activity was repeated in triplicate and the average was recorded. For our purposes, we define one unit (U) of bacteriocin activity as equal to 1 mm 2 of the zone of inhibition of growth of the indicator bacterium [12,13].…”