Evaluaci&oacute;n de cloruro de calcio como inhibidor de la bacteria <em>Zymomonas mobilis</em> en fermentaciones de ron

Abstract

<em>Zymomonas mobilis</em> es una bacteria Gram negativa, anaerobia facultativa, que se considera un contaminante durante las fermentaciones de rones, afectando el aroma y la producci&oacute;n de etanol. Este estudio comprob&oacute; la eficacia de adicionar una sal de calcio para la atenuaci&oacute;n metab&oacute;lica de <em>Z. mobilis</em> en fermentaciones de mieles de ca&ntilde;a. Se evalu&oacute; el efecto de distintas concentraciones de cloruro de calcio sobre el desempe&ntilde;o de <em>Z. mobilis</em> y la levadura <em>Saccharomyces cerevisiae</em> en fermentaciones con par&aacute;metros controlados (temperatura, agitaci&oacute;n, grados Brix, pH y concentraciones de cloruro de calcio). Se realizaron recuentos celulares en una c&aacute;mara Neubauer, medici&oacute;n de &deg;Brix aparentes, y an&aacute;lisis por HPLC para la determinaci&oacute;n de la concentraci&oacute;n de glucosa, fructosa, sacarosa y etanol en diferentes etapas de la fermentaci&oacute;n. Se concluy&oacute; qu&eacute; en fermentaciones de mieles de ca&ntilde;a diluidas, la adici&oacute;n de cloruro de calcio a una concentraci&oacute;n de 0.05 M aparenta retardar el crecimiento de <em>Z. mobilis</em>, alcanz&aacute;ndose una inhibici&oacute;n completa de la bacteria a una concentraci&oacute;n de 0.10 M de esta sal, sin afectar adversamente el desempe&ntilde;o de <em>S. cerevisiae</em>.

<em>Zymomonas mobilis</em> is a Gram-negative, facultative anaerobic bacteria, commonly considered a contaminant during fermentation of rums, impacting aroma and ethanol production. This study corroborates the efficacy of adding a calcium salt for the metabolic attenuation of <em>Z. mobilis</em> in fermentations of diluted sugar cane molasses. We evaluated the effect of different concentrations of calcium chloride on the performance of <em>Z. mobilis</em> and the yeast <em>Saccharomyces cerevisiae</em> in fermentations with several controlled parameters such as temperature, agitation, Brix degrees, pH, and calcium chloride concentrations. In this study, cell counts were performed using a Neubauer chamber, apparent &deg;Brix measurements were done, and used HPLC analysis to determinate the concentration of glucose, fructose, sucrose, and ethanol at fermentation different stages. As part of our findings, it was concluded that in fermentations of diluted sugar cane molasses, the addition of calcium chloride at a concentration of 0.05 M appears to decelerate the growth of <em>Z. mobilis</em>, achieving a complete inhibition of the bacteria at a concentration of 0.10 M of this salt, without adversely affecting the performance of <em>S. cerevisiae</em>.