Identificación de bacterias termodúricas en leche utilizada para la elaboración de quesos frescos artesanales en la parroquia rural de Quimiag de la provincia de Chimborazo.

Abstract

The objective of this study was to quantify and identify thermoduric bacteria present in pasteurized milk used in the preparation of fresh artisan cheeses in Quimiag rural parish in Chimborazo province. A count of aerobic mesophiles and thermoduric lactic acid bacteria was made in samples of raw milk: with treatment in the cheese and with treatment in the laboratory; subsequently, successive plantings to obtain isolated pure were made, to which a tests (indole,hydrolysis of gelatin, catalase, oxidase, sulfide indole motility (SIM), susceptibility to antibiotics). The results show that the heat treatment that the milk receives in the cheese factory decreases the count of mesophilic aerobic and lactic acid bacteria, compared with the results of heat treatment that you received in the laboratory. With regard to the isolation and identification, twenty isolated identified microscopically were obtained, Gram-positive and Gram-negative bacteria. By phenotypic test they proved to be catalase and oxidase negative, not producers of indole and hidrolizadores of gelatin, with little mobility, highly sensitive antibiotics such as erythromycin, amoxicillin, tetracycline and resistant to gentamicin and vancomycin. Despite the lack of thermal shock, the heat treatment in the cheese factory decreases the load microbiana of lactic acid bacteria with regard to the laboratory treatment, which would explain the less accentuated taste aroma in cheeses made with this type of milk. It is recommended the realization of molecular test for the identification of this type of bacteria, due to the fact that most of them could be used in the food industry as probiotics or improve sensory and nutritional characteristics of the cheese.