Aislamiento, Caracterización y Selección de Bacterias Lácticas Autóctonas de Leche y Queso Fresco Artesanal de Cabra

Abstract

ResumenSe aislaron y caracterizaron 18 cepas autóctonas de bacterias con el objetivo de seleccionar aquellas con características funcionales definidas para ser utilizadas como cultivos iniciadores en la producción de queso fresco. La investigación se dividió en tres etapas: (1) evaluación de las características funcionales (actividad proteolítica, actividad lipolítica, capacidad acidificante y producción de gas); (2) selección e identificación fenotípica de las cepas y (3) validación de su aplicación como cultivos iniciadores a nivel de laboratorio (pruebas de antagonismo y cinética de crecimiento en leche). Los géneros identificados fueron Lactobacillus (56%), Lactococcus (22%) y Leuconostoc (22%), que presentaron bajo poder acidificante, sin producción de gas y sólo 3 de las 18 cepas presentaron actividad lipolítica, mientras que la mayoría desarrolló actividad proteolítica. A partir de los parámetros cinéticos evaluados, es posible inferir el desempeño de las cepas lácticas, permitiendo con ello mejorar el control sobre los procesos, la vida útil y la calidad microbiológica del producto lácteo terminado.Palabras clave: cepas autóctonas; bacterias ácido lácticas; queso fresco; cultivo iniciador. Isolation, Characterization and Selection of Autochthonous Lactic Acid Bacteria from Goat Milk and Fresh Artisanal-Goat Cheese AbstractEighteen indigenous strains of bacteria were isolated and characterized in order to select those with defined functional characteristics, to be utilized as starter cultures in the production of fresh cheese. The research was divided into three stages: (1) evaluation of functional characteristics (proteolytic activity, lipolytic activity, acidifying capacity and gas production); (2) selection and phenotypic identification of strains and (3) validation of their application as starter cultures at laboratory scale (tests of antagonism and growth kinetics in milk). Lactobacillus (56%), Lactococcus (22%) and Leuconostoc (22%) were the genders identified, they showed low acidifying power, without gas production and only 3 of 18 strains presented lipolytic activity, whereas most of them developed proteolytic activity. From the kinetic parameters calculated in this study is possible to determine the performance of the strains allowing to better control the process, increase the shelf life and quality of the final milk product.

Growth kinetics of Lactococcus lactis and Lactobacillus casei in liquid culture medium containing as prebiotics inulin or fructose

“…However, fructose as a carbon source significantly promoted the growth of L. lactis (CU‐R‐704) and L. casei (CU‐L‐CASEI). These results are incompatible with previous studies by Ramírez‐López and Vélez‐Ruiz 58 who obtained in their research work with the L. lactis strain isolated from raw milk and fresh artisanal goat cheese, growth with cell concentrations up to 7.90 log (CFU mL −1 ) in the medium formulated with fructose, results that are much lower than ours, where it was established that the highest cell concentrations in log biomass (DO 600nm ) and number of estimated cells log (cells mL −1 ) in the strains of L. lactis (CU‐R‐704) and L. casei (CU‐L‐CASEI) fluctuated between 0.24 log (g cells L −1 ) or 0.59 g cells L −1 , 8.99 log (cells mL −1 ) or 9.60 × 10 8 cells mL −1 , 0.068 log (g cells L −1 ) or 0.18 g cells L −1 , 8.19 log (cells mL −1 ) or 1.54 × 10 8 cells mL −1 in medium formulated with fructose as carbon source.…”

“…However, the value of the maximum growth rate ( μ max ) had a greater impact on the adjustment of the exponential growth phase, in which treatment A1B1 had the best value with 0.21 h −1 . These results are incompatible with previous studies by Ramírez‐López and Vélez‐Ruiz 58 who, applying the primary growth model of Baranyi and Roberts, 70 determined that Lactococcus lactis , under the addition of fructose in culture medium, reached the value of μ max of 0.377 h −1 . It was observed in a different study 71 that the μ max of L. lactis can be as high as 0.91 h −1 under low aeration conditions.…”

“…Its ability to degrade various carbohydrates is well established and it is known that it depends on the strain that it contains, 51‐54 which could also be evidenced in our study. In addition, the exponential growth kinetics were observed in all the treatments tested, showing excellent growth with values of maximum cell concentrations that were above the range established at BAL of 1.0 × 10 6 and 1.0 × 10 7 cells g −1 of product, as a level recommended for probiotics in fermented cheese‐type products 55‐61 . It is for this reason that the strains studied can be used in the preparation of inocula with probiotic properties that will allow competition against pathogenic microorganisms, facilitating the colonization of cheese and its derivatives.…”

“…In addition, the exponential growth kinetics were observed in all the treatments tested, showing excellent growth with values of maximum cell concentrations that were above the range established at BAL of 1.0 × 10 6 and 1.0 × 10 7 cells g −1 of product, as a level recommended for probiotics in fermented cheese-type products. [55][56][57][58][59][60][61] It is for this reason that the strains studied can be used in the preparation of inocula with probiotic properties that will allow competition against pathogenic microorganisms, facilitating the colonization of cheese and its derivatives. In this study, two types of sugars (fructose and inulin) were used as carbon sources in the growth medium to find a suitable sugar on the optimal exponential growth of the mentioned strains.…”

Biochemical Characterization of Lactic Acid Bacteria from the Small Intestine of Piglets as Possible Probiotic Strains

“…En relación al tamaño de las cepas aisladas tienen un mínimo de 0,1mm hasta 5mm de diámetro como se describe en el cuadro 4 la cuales son casi similares a lo descrito por [9] al igual que [10] los cuales manifiestan que las cepas de Lactobacillus formaron colonias cuyo tamaño fue de 1 a 2 mm, de color blanco cremoso, de forma redonda, puntiformes, con bordes enteros, y superficie convexa, de consistencia butirosa.…”