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Mastitis is responsible for both damage to animal health and economic losses to the industry. To identify effective treatments for this disease, products extracted from a variety of plants with antimicrobial potential have gained attention. The present study aimed to assess the in vitro antibacterial potential of the ethanolic extract of two plant species from the Caatinga biome against bacteria isolated from small ruminants with subclinical mastitis. The leaves of Mimosa tenuiflora and Commiphora leptophloeos were dried and processed to obtain crude ethanolic extracts and their phenolic composition was evaluated. In total, 33 Staphylococcus spp. isolates from the bacterial collection of the Laboratory of Food Quality Control of IF SERTÃO-PE were used for evaluation of biofilm production. Furthermore, an antimicrobial susceptibility test was conducted using the minimal bactericidal concentration (MBC) method against the two ethanolic extracts. The toxic potential was measured through a toxicity test with Artemia salina. The quantification of the phenolic compounds revealed that the ethanolic extracts of M. tenuiflora and C. leptophloeos possessed higher amounts of myricetin (43.2 and 294.9 mg in 10 g, respectively) in relation to the other compounds. A 39.4% positivity rate was observed in the nuc gene investigation. The biofilm production analysis revealed that 96.9% of the isolates produced biofilm, evidencing the evolution the microorganisms regarding the development of resistance mechanisms. The MBC results showed an inhibition range between 195.30 and 3125.00 µg mL-1 and between 781.20 and 6250.00 µg mL-1 for the extracts of M. tenuiflora and C. leptophloeos, respectively. The M. tenuiflora extract showed the highest activity, suppressing 100% of the bacterial isolates (n=26), whereas the extract of C. leptophloeos showed an inhibition percentage of 69.23%. The crude ethanolic extract (EEB) of M. tenuiflora was found to be toxic, presenting a DL50 of 118.356 µg mL-1. In contrast, the EEB of C. leptophloeos was found to be non-toxic (DL50 = 1527.430 µg mL-1). In conclusion, both native Caatinga species presented antibacterial activity and myricetin was the major compound. These findings highlight the need for further studies regarding the identification of anti-mastitis products from natural extracts.

Coalho cheese is a typical Northeastern Brazilian food whose production and consumption has expanded considerably to other regions of the country. Despite its cultural and socioeconomic relevance, coalho cheese still has a negative reputation due to problems in its physicochemical and microbiological quality standards, especially when it is produced artisanally. For this reason, many researchers have been looking for alternatives to improve the quality and the notoriety of this product, such as the application of probiotic strains to inhibit pathogens. However, in addition to the research related to the desired probiotic properties and the safety of strains for food application, it is important to know the possible changes in the food matrix caused by this intervention. In this context, the aim of this study was to evaluate the effect of the incorporation of probiotic strains of Enterococcus faecium on the physicochemical and sensory characteristics of coalho cheese. The cheeses were made with pasteurized cow milk and probiotic strains of E. faecium were added during production. Cheeses were also made without adding the strains, and considered as control cheeses. The final products were evaluated for moisture, pH, titratable acidity, total carbohydrates, proteins, lipids, ash, color, organic acid profile, and sensory attributes. In addition, viable lactic acid bacteria were also assessed. Coalho cheeses containing E. faecium showed higher titratable acidity and lower pH. In addition, there was a reduction in the carbohydrate content, which was attributed to lactose degradation. The organic acid profile also varied, as highlighted by the increase in the concentration of lactic acid by a factor of 3.5, and by the absence of citric acid as a possible result of the metabolism of E. faecium in the production of aromatic compounds. There was no variation in the color or sensory acceptance of the cheeses. Therefore, the application of probiotic strains of E. faecium in coalho cheese production changes some physicochemical characteristics while maintaining essential properties, such as the color and sensory acceptability of the final product.