AISLAMIENTO E IDENTIFICACIÓN MOLECULAR DE UNA CEPA DE Lactobacillus delbrueckii subespecie bulgaricus EN LECHE DE CABRA (Capra hircus)

La leche de cabra ( Capra hircus ) constituye una alternativa alimentaria y una fuente importante de microorganismos, entre los cuales se encuentra, el Lactobacillus delbrueckii subesp. bulgaricus de amplio uso en la produccion de yogurt y quesos madurados. En este sentido, se planteo el aislamiento e identificacion en leche de cabra de una cepa de Lactobacillus delbrueckii subsp. bulgaricus de interes biotecnologico, como fermento lactico. Se analizaron muestras de leche de cabra procedentes de la Unidad Experimental de Caprinos de la Facultad de Ciencias Veterinarias Universidad Central de Venezuela (UNEXCA-FCV-UCV). En el aislamiento, se emplearon los medios selectivos caldo y agar MRS (Man, Rogosa y Sharpe). Se identifico a nivel fenotipico por caracteres morfologicos y fermentacion de azucares, y genotipicamente por secuenciacion del ADNr 16S con iniciadores universales HDA1 y WLAB2. Ademas, se evaluo el crecimiento bacteriano, accion patogena, desarrollo de acidez, reduccion del contenido de lactosa y capacidad proteolitica del lactobacilo sobre la caseina (Cs), alfa-lactoalbumina (-La) y beta-lactoglobulina (-Lg), con registros de absorbancia a 595nm y apreciacion de productos en geles discontinuos de poliacrilamida SDS-PAGE. El modelo estadistico aplicado fue del tipo descriptivo con empleo del software statistics version 10.0. La cepa aislada de Lactobacillus delbrueckii subsp. bulgaricus fue nombrada como CIL 1671 FCV-UCV, la cual mostro una excelente capacidad fermentativa con rapido desarrollo de acidez en 4 h de incubacion a 42 ± 1°C, no exhibio accion patogena  y presento capacidad hidrolitica sobre la Cs, -La y -Lg, lo que le confiere alto valor biotecnologico como fermento en la industria lactea. ( Palabras clave : Lactobacillus ; cabra ( Capra hircus ); leche) Abstract Goat milk ( Capra hircus ) is a food alternative that represents an important source of microorganisms, among which is the Lactobacillus delbrueckii subsp. bulgaricus , widely used in the production of yogurt and ripened cheese. In this sense, the objective of this investigation was the isolation and identification in goat milk, of a strain of Lactobacillus delbrueckii subsp. bulgaricus , of biotechnological interest as a lactic ferment. To carry out this investigation, samples of goat milk from the Goat Research Unit (UNEXCA) of the Facultad de Ciencias Veterinarias of the Universidad Central de Venezuela, located in Maracay, the State of Aragua, were analyzed. For the microorganism isolation, the selective culture media MRS (De Man, Rogosa and Sharpe) Broth and the MRS Agar were used. Once the strain was isolated, it was identified phenotypically, by morphological characters and fermentation of sugars and, genotypically, by sequencing the 16S rDNA with universal primers HDA1 and WLAB2. The bacterial growth, pathogenicity, development of acidity, reduction of lactose content, and proteolytic capacity of lactobacillus, were also evaluated on casein (Cs), alpha-lactalbumin (-La), and beta-lactoglobulin (-Lg), with absorbance records at 595 nm and product evaluation in SDS-PAGE polyacrylamide discontinuous gels. The statistical model applied was of the descriptive type, using the software Statistics, version 10.0. The isolated strain of Lactobacillus delbrueckii subsp. bulgaricus , was called the CIL 1671 FCV-UCV and showed an excellent fermentative capacity, with rapid development of acidity in 4 hours of incubation at 42 ± 1 °C. The strain did not exhibit pathogenicity and showed a hydrolytic capacity on Cs, -La and -Lg, which confers high biotechnological value as ferment in the dairy industry. ( Key words : Lactobacillus ; goat ( Capra hircus ); milk)