The objective of this work was to evaluate the survival of a Brucella abortus aqpX mutant during the elaboration and conservation of fresh and ripened cheeses at 4 C and 24 C. The pH values and water activity were monitored for each type of cheese. The fresh cheese was elaborated with raw milk inoculated with 6×108 colony-forming units (CFU)/mL each of parental and mutant strain. Ripening cheeses were elaborated with both raw and pasteurized milk and inoculated with 12×108 CFU/mL each of parental and mutant strains. In fresh cheese, survival was observed during elaboration and conservation for 7 days at 4 C in mutant and parental strains. The number of survivors of the mutant strain was 10 times lower compared with the parental strain at pH 5 and aw of 0.930. In the cheese elaborated with raw milk and ripened at 24 C, both strains survived until day 17 at pH 4.0 and aw of 0.89. However, when the cheese was elaborated with pasteurized milk, the parental strain survived until day 31 of ripening, and the mutant strain survived 24 days at pH 4 and aw of 0.886. The survival of the mutant strain showed a diminution of one logarithm during elaboration and ripening of cheese as compared with the parental strain. When the cheese was elaborated with raw milk and ripened at 4 C, survival of the parental strain was 24 days, whereas the mutant strain survived only 17 days (pH 5 and aw 0.90). Regarding the cheese elaborated with pasteurized milk and maturated at 4 C, both strains survived 31 days (pH 5 and aw 0.90), with the same survival diminution during elaboration and ripening. Our results show that in both types of cheese, the mutated aqpX strain survived 10 times less than the parental strain, which shows that the aqpX gene can be related to the survival of Brucella abortus in this type of cheese.

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