In the North region, gastric cancer (GC) ranks second of the most frequent types of tumors in men and fourth in women. For 2016, were estimated 690 new cases in the state of Pará, 260 cases in the capital. GC has a multifactorial etiology, resulting from the interaction of genetic (endogenous) and environmental (exogenous) factors. Epidemiological studies have shown a clear association between the excessive consumption of salt-preserved foods and the occurrence of GC, this is mainly due to the carcinogenic action of N-nitroses compounds resulting from the union of Nitrate reduction pathway (from salting) products and of organic compounds present in the stomach region. This reduction is performed by bacterial enzymes (nitrate reductase) that are present in contaminating species that can proliferate in this type of food. Such salt-preserved foods, such as pirarucu (among other fish), shrimp and charque, have been incorporated for many years into the food pattern of the state of Pará and other areas of the Amazon region. This reduction is performed by bacterial enzymes (nitrate reductase) present in contaminating species that can proliferate in this type of food. Salt-preserved foods, such as pirarucu (among other fish), shrimp and charque, have been incorporated for many years into the food pattern of the state of Pará and other areas of the Amazon region. During the salting process, the time and conditions of processing, storage and commercialization of the food are directly related to the quality of these products. For this reason, the importance of studies that evaluate alternative processing conditions, such as use of refrigeration, in order to mitigate the production of components harmful to human health. In the present study, we investigated the bacterial composition in different salting processes of these foods, through bacterial and metagenomic isolation. Samples of fresh pirarucu evidenced growth of E. coli, indicating microbial contamination of fecal origin, which was not noticed in the samples submitted to salting. From the metagenomic analyzes we can observe an abundance of the genus Staphylococcus in the samples of salted fish, especially in those kept exposed at room temperature. This genus contains species that cause toxinfections and have the enzyme nitrate reductase. The contamination of pirarucu by these bacterial species leads to the production of nitrite, which when consumed lead to the formation of carcinogens involved in the formation of mutations, which may trigger gastric neoplasms. Although refrigeration has diminished the bacterial quantitative, the bacteriostatic or bactericidal effect of the salting process was not sufficient to maintain the quality of the salted fish in levels suitable for consumption, therefore, the consumption of the fish can be harmful to the health of the population and be related with high GC rates in the population of Belém and the North region.
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