Caracterización bioquímica y espectro de inhibición microbiana de las bacteriocinas producidas por Lactobacillus buchneri y Lactobacillus paracasei
Lactic acid bacteria (LAB) are able to produce a number of metabolites with antimicrobial ability. Bacteriocines are a group of biological compounds produced by these microorganisms that may be applied to extend food shelf-life. These peptides are active against Gram positive bacteria, their inhibit...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2004 |
| País: | México |
| Institución: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:6t053g51f |
| Acceso en línea: | https://doi.org/10.24275/uami.6t053g51f |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/LEM/Bacterias lácticas info:eu-repo/classification/LEM/Bacteriocinas info:eu-repo/classification/LEM/Bacteriocins info:eu-repo/classification/LEM/Lactic acid bacteria info:eu-repo/classification/cti/3 |
| Sumario: | Lactic acid bacteria (LAB) are able to produce a number of metabolites with antimicrobial ability. Bacteriocines are a group of biological compounds produced by these microorganisms that may be applied to extend food shelf-life. These peptides are active against Gram positive bacteria, their inhibition spectra includes several toxic and infectious bacteria such as Listeria monocytogenes and Clostridium botulinum. Due their heat resistance, some bacteriocins can be also applied on foods together with other preservation methods. However, in order to efficiently apply bacteriocins in real food systems, optimization of the preservation process involved is necessary through control at biochemical, microbial and technical levels. The present thesis studied the bacteriocins produced by two LAB (Lactobacillus buchneri and Lactobacillus paracasei), isolated from red meats. Several production, activity and stability characteristics of these bacteriocins were studied. The experiments carried out were focused on biochemical and physiological properties of the bacteriocins and the producing bacteria as preliminary studies for the futher use these compounds in red meat preservation. The first part of the thesis was the study of the bacteriocins¶ inhibition spectra. It was observed that Lactobacillus buchneri and Lactobacillus paracasei bacteriocins inhibited the growth of Listeria monocytogenes NCTC 11994 and L. monocytogenes LMB 92000/48 respectively. Studies were also carried out in order to determine the bacteriocins¶ biochemical characteristics. The bacteriocin produced by Lactobacillus buchneri was resistant to heating at 100°C during 20 min showing circa 15% activity reduction, also observed in the bacteriocin produced by Lactobacillus paracasei when subjected to similar heating conditions. The highest activity for both bacteriocins were observed at pH 3.0 to 4.0. It was concluded that both properties favor the bacteriocin application in high acid foods. The ability to inhibit Listeria monocytogenes growth as well as their heat resistance suggested that the bacteriocins belong to Group II (no-lantibiotics), Class IIa. Even thougth, it is necessary to determinate their aminoacid sequence and molecular weight in order to confirm this classification. The studied bacteriocins kept their antimicrobial activity during storage at 4°C for 10 days, therefore it can be assumed that these compounds can be applied to foods under refrigeration conditions. They were adsorbed by their producing cells in a pH range from 5.5 to 6.5. This property could be used to improve their diffusion, preventing cell adsorption when applied in foods by in situ production. A primary production pattern was observed for both bacteriocins. Production under the experimental conditions was related to microbial growth, favored by a nitrogen atmosphere. With respect to production temperature, 30°C was the optimum for Lactobacilus buchneri and 35°C for Lactobacillus paracasei. It was also observed that 1% Tween 80 increased the recovery rate of both bacteriocins. Althougth the studies at laboratory level cannot fully explain production, activity and stability dynamics for these bacteriocins in food systems preservation, these results can contribute towards a more efficient use of bacteriocins in foods by in situ production as well by the use of the purified compounds. |
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