Evaluación de métodos de lisis celular para la obtención de extracto de levadura a partir de Saccharomyces cerevisiae

Abstract

El tema de este trabajo de graduación surge a partir de mi interés en la reutilización de compuestos residuales en industrias grandes como la azucarera y producción de bebidas alcohólicas. A lo largo de mi carrera universitaria, aprendí acerca del potencial que tiene la biotecnología en tomar los residuos de una industria para un nuevo proceso y obtención de productos de valor. Además, al conocer y estudiar sobre la amplia gama de aplicaciones de las levaduras, me llamó la atención la producción del extracto de levadura y el potencial que este producto tiene en la industria. Mi interés por el área de bioprocesos, me llevó a investigar sobre técnicas de ruptura celular para la obtención del extracto de levadura, como forma de mejorar la efectividad de producción de compuestos de alto valor biológico.

Yeast extract is a high-value product in the market, due to its wide range of applications from various industries. Considering the raw material of this product is yeast, there is a great availability in the industry. Naturally, considering that in the production of ethanol, alcoholic beverages use this microorganism to obtain their product of interest and up to 28 thousand tons of residual yeast can be produced per year. Therefore, there is great potential in the implementation of protocols for obtaining yeast extract from this industry's subproduct. In the present research, different methods of cell lysis were studied, starting from the growth of a selected strain of S. cerevisiae. A concentration of 4.54* 1013 ± 2.79*10-1 g/g of yeast cells was obtained in the last step of the propagation process, with a volume of 85 L. From the viable yeast obtained, tests of cell lysis methods were carried out. After a statistical analysis of the test of variance and Tukey's test, the methods with the highest and least effectiveness to reach a complete lysis of the yeast were determined. Mechanical lysis was determined as the least effective method, where cell viability did not fall below 50 % in any of the three repetitions performed with the method. On the contrary, acid and basic hydrolysis performed with solutions of hydrochloric acid and sodium hydroxide, respectively, in a concentration of 1.5 M, proved to be the most effective in lowering viability. Of course, taking into account that they were the methods that required the least time to reach a viability of 0 %, around 2 minutes after the start of the reaction. Finally, a final amount of 121,542 ± 5*10-5 g of yeast extract was obtained from about 10g of selected yeast. A characterization of the protein of the final product obtained was carried out, where a measurement of the total nitrogen in a solution made with the extract was performed. In this, a concentration of 5.15 ± 5.24 * 10-3 % m/m of total nitrogen was obtained, equivalent to 38.85 ± 1.02 * 10-2 % m/m of protein in the final product.