Caracterização da diversidade genética de Escherichia coli isoladas de amostras de água de mananciais que abastecem queijarias representativas da Serra da Canastra - MG

The Serra da Canastra region is recognized as a highly important cradle for the production of Canastra Artisanal Minas Cheese (QMAC), whose production chain is linked to local natural resources. The management of the agroecosystem directly influences the quality of the water sources that supply rural properties and cheese factories, given that water is widely used in the sanitation stages of equipment and facilities that come into contact with raw milk. The presence of contaminants, especially of microbiological origin, can compromise both the quality of the final product and the health of consumers. Among the bacterial agents indicative of fecal contamination, the species Escherichia coli naturally inhabits the intestines of humans and other warm-blooded animals, standing out for its epidemiological relevance and for being an excellent marker of hygienic-sanitary conditions in water and food, and its isolation and molecular characterization are essential tools for evaluating the variety of genetic profiles in the scenario of the region's agroecosystems. The objectives of this study were to characterize the genetic diversity of E. coli isolates from water samples from rivers in Serra da Canastra that supply cheese factories representative of the region. Water samples were collected from 12 rivers located around Serra da Canastra National Park during the 2022 drought period, distributed in three different weekly campaigns, at points close to the intakes used in the production of Queijo Canastra, with up to ten collection points per source. The presumptive isolation of E. coli was performed on a specific chromogenic medium, followed by confirmation on MacConkey Agar. A number of 184 isolates with pink coloration indicative of lactose fermentation, gram-negative rod morphology and adequate growth with E. coli were considered confirmed and selected for the molecular characterization stage. The genomic DNA of the isolates was extracted using a saline occurrence protocol and then quantified. The isolates from each of the twelve rivers were subjected to the rep-PCR (GTG)5 molecular fingerprinting technique to identify clonal lineages. The evaluation of the molecular profiles allowed the exclusion of 64 isolates (34.78%) considered clones of other isolates within the same river, with only one representative of each profile being maintained for subsequent analyses. River 4 showed low diversity, with 100% of the isolates belonging to the same genetic profile. On the other hand, river 10 exhibited the highest clonal diversity, with each dominant profile representing only 8% of the isolates. The results obtained in this research are presented to better understand the diversity of E. coli in the studied ecosystem and for the subsequent development of analyses of the virulence and resistance potential of this bacterial group that contaminates the water that supplies the production line of the final product, Canastra Cheese.