Biotechnological production and purification of plantaricin by Lactobacillus plantarum St16Pa using natural culture medium

Abstract

Bacteriocins are ribosomal peptides which possess antimicrobial activity against various pathogenic microorganisms. These compounds, when produced by lactic acid bacteria, i.e. generally recognized as safe (GRAS), have a great interest due to the potential for application in the food industry, as a natural preservative. The plantaricin is a bacteriocin produced by probiotic bacterium Lactobacillus plantarum, which comes gradually being studied as a bio preservative of foods, besides presenting great potential for application in pharmaceutical field. The use of milk whey, as an alternative and natural culture medium, praises the concept of production of a biomolecule of high added value coupled with the environmental aspect. Various studies have demonstrated the ability that the inulin and sucrose have as alternative sources of carbon, in addition to promote the growth of lactic acid bacteria. In the case of application of the inulin, it becomes increasingly more important to study the interactions between the bacteria using this prebiotic during the fermentation process, in order to increase the production of biomolecules of high added value, such as bacteriocins. In this context, this project has the aim of studying the variables that influence the production of plantaricin by L. plantarum in metabolic shaker and in bioreactor of 3 liters. Studies will be carried out with the aid of experimental planning, about the influence of relevant variables in the production of bacteriocin by L. plantarum ST16Pa, as: concentration of whey; concentration of sucrose and inulin as alternative sources of carbon, pH and temperature of conduction of the fermentative process. During the cultivations in metabolic shaker, samples shall be collected at intervals of 6 hours for analysis of pH, concentrations of sugars (lactose, glucose and fructose), lactic acid, biomass and activity of plantaricin. In the cultivations in bioreactor, where it aims to establish effective conditions for an industrial application, is to be taken the decision to experimental planning DCCR (Central Composite Design Rotational) to 2 factors: agitation (100, 150 and 200 rpm) and aeration (0.5, 1.0 and 1.5 vvm), expressed by volumetric coefficient of oxygen transfer (kLa). In this case, will be used the medium which have led to the maximization of the response (antimicrobial activity and production of plantaricin) and minimization of cost obtained in metabolic shaker tests. In bioreactor, the cultivation time, originally scheduled for 48 hours, it can be changed after the initial experiment, a time that will be assessed at that stage of cultivation if you find the microorganism. In this stage of the process, samples shall be collected at intervals of 6 hours for analyzes of the concentration of lactic acid, cell growth, sugars (lactose, glucose and fructose) and activity of plantaricin. The analyzes shall be performed in triplicate. Both the pH and the level of dissolved oxygen will be monitored in real time by the respective probes coupled to the bioreactor. In addition, will be standardized and optimized a purification method suitable of plantaricin aiming at a future industrial application, both in the food industry such as in pharmaceuticals. (AU)