Microbiological Characteristics and Behavior of _Staphylococcus aureus_, _Salmonella_ spp., _Listeria monocytogenes_ and Staphylococcus Toxin during Making and Maturing Cotija Cheese  
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1 Departamento de Farmacobiologia, Centro Universitario de Ciencias Exactas e Ingenierias, Universidad de Guadalajara, Blvd. Gral. Marcelino Garcia Barragan 1421, Olimpica, Guadalajara 44430, Mexico; mariangeles,[EMAIL_ADDRESS] (M.d.I.A.O.-R.)12 Food Technology Department, Centro de Investigacion y Asistencia en Tecnologia y Diseno del Estado de Jalisco (CIATED), Av. Normalistas 800, Colinas de la Normal, Guadalajara 45019, Mexico; [EMAIL_ADDRESS] 2  
Citation: [PERSON]; [PERSON];[PERSON]; [PERSON].  
formation of inhibitory compounds for certain microorganisms [5]. The microbiota is an essential component that plays an essential role during cheese maturation [6; 7]. Interaction within the milk microbiota is vital for the characteristics of the final product. It participates from the acidification of the curd to the formation of compounds that determine the aroma, flavor, and texture during ripening [8; 9]. Even raw milk is used in the elaboration of some matured cheeses. Therefore, the diversity of the native microbiota contributes to the final sensory properties and biopreservation [10; 11].  
Cotija cheese is a typical matured Mexican cheese that is artisanal-made and produced exclusively with milk from crosses of zebu cattle (_Bos taurus indicus_). It is manufactured from July to October in the Cotija area, located between the states of Jalisco and Michoacan. The salt added during the manufacturing process contributes to its flavor and firm consistency. During the aging process, salt concentration and other solutes produce a reduction in the water activity, promoting a selective medium in which halo-tolerant microorganisms like various genera of lactic acid bacteria dominate others, transform the physicochemical properties and composition of the cheese. Although the action of the different microbial populations from the milk used, the environment of the cheese factory and the production practices, the climatic conditions of the geographical area where the cheese is made and matured, favor the dynamics of the microbial populations, characteristics and, consequently, the distinctive characteristics of this cheese [5; 12; 13].  
During the ripening process, adverse conditions are created for the development of pathogens. In the case of Cotija cheese, salt is added. However, some pathogenic bacteria may survive, causing health problems. An example occurred in Illinois due to the consumption of cheese produced in the USA, marketed as Cotija, contaminated with _Salmonella enterica_ serotype Newport [14]. Another pathogen frequently recovered in Cotija cheese is _Staphylococcus aureus_, which can originate from the mammary glands of infected cows [15].  
The objective of this work was to investigate microbiological characteristics and behavior of _Staphylococcus aureus_, _Salmonella_ spp., _Listeria monocytogenes_ and staphylococcal toxin during elaboration and maturation of Cotija cheese.