BackgroundBoth diarrhea in calves and mastitis in cows limit cattle production. The bacteria involved in these diseases have shown multi-resistance to antimicrobials, however plant metabolites therefore can provide an alternative method of control. This study selected and characterized Cerrado plant extracts showing inhibitory effects against Escherichia coli and Staphylococcus spp. from cattle. Thirteen leaf extracts were initially screened and diameters of inhibition zones produced against the pathogens were recorded using an agar disk diffusion method. Total condensed tannin contents were determined and antibacterial activities were analyzed after tannin removal from the five selected extracts. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were evaluated by macro-dilution antimicrobial susceptibility tests, and the extracts were characterized by high performance liquid chromatography.ResultsInter- and intra-specific bacterial variations in the susceptibility to the extracts were detected. The aqueous extract (AE) from Caryocar brasiliense Cambess. leaves produced larger inhibition zones against E. coli strains than did other selected extracts. However, the AE from Schinopsis brasiliensis was the most effective against Staphylococcus spp. strains (P < 0.001). The MIC of ethanolic extracts (EE) from C. brasiliense (0.27 mg/mL) and S. brasiliensis (0.17 mg/mL) were lower than those of other extracts. The MIC and MBC of the Annona crassiflora EE were 6.24 mg/mL for all bacteria. Flavonoids were the main metabolites detected in the A. crassiflora EE as well as in the AE and EE from C. brasiliense, while tannins were the main metabolites in the S. brasiliensis leaf extracts.ConclusionThe AE from C. brasiliense was more effective against Gram-negative bacteria, while the AE from S. brasiliensis was more effective against Gram-positive bacteria. A. crassiflora EE and S. brasiliensis extracts are potent bactericide. After removal of the tannins, no antimicrobial effects were observed, indicating that these metabolites are the main active antibacterial components.

Human ingestion of antimicrobial residues in dairy products is a problem of public health. In this study we evaluated antibacterial effectiveness of aqueous and ethanolic leaf extracts of Mangifera indica L. as a natural alternative for reduction of Staphylococcus spp. biofilms. Eight Staphylococcus spp. strains from cows with mastitis and the Staphylococcus aureus strain (ATCC 25923) were evaluated. High performance liquid chromatography indicated the presence of phenolic compounds in the aqueous extract. Agilent Technologies gas chromatography revealed the presence of phenolic compounds, carbohydrates, and gallic acid in ethanolic extract. The tannin contents were 2.27 ± 0.01 and 2.67 ± 0.01% for ethanolic extract and aqueous extract, respectively. Extracts were evaluated in agar diffusion test and the size of inhibition zones were compared. The ethanolic extract was the most effective, showing minimum inhibitory concentrations and minimum bactericidal concentrations between 1.8–7.5 and 15.1–45.3 mg/ml, respectively. After tannin removal, the extracts were less effective, indicating these secondary metabolites as one of the main antibacterial compounds. The ethanolic extract at 45.3 mg/ml reduced mature biofilms in teat rubber (average: 3.91 log reduction) and stainless steel (average: 3.87 log reduction) after 5 min of contact. The extracts of M. indica leaves represent natural alternatives against Staphylococcus spp. strains and the ethanolic extract shows potential as a natural sanitizer.

Staphylococcus spp. represents the main mastitis agents in ruminants and contaminants of milk due to their expressive capacity to make biofilms. The aims in this study was evaluate evaluated the antimicrobial activity of Mauritia flexuosa L. extracts against Staphylococcus spp. adhered to a stainless steel surface. Two isolates from cows with clinical mastitis were evaluated; one was identified as Staphylococcus aureus, and the other Staphylococcus haemolyticus. Additionally the ATCC 25923 strain, S. aureus from human was evaluated. The chemical profile obtained from gas chromatography revealed the presence of carbohydrates, organic acids, and flavonoids. The minimum bactericidal concentrations of the ethanolic extract (EE) and aqueous extract (AE) were 4.4 and 5.82 mg/mL, respectively. After EE treatment at 4.4 mg/mL for 2.5 min, total removal of mature biofilms grown on stainless steel coupons was observed (reduction by 3.85-4.81 log units). This extract from M. flexuosa shows potential as an effective sanitizer and may represent a natural alternative against Staphylococcus spp.

In this study, four milk substrates were analyzed to evaluate bovine Lactobacillus plantarum strain viability after 24 and 48 h of fermentation. In addition, cell viability, and post-acidification in transition milk fermented by these bacteria were assessed over a 60-d storage period at 4 and 25 °C. Significant reduction (30.9 %) of cell viability after 48 h of fermentation was observed for the formulation with whole milk. However, in fermented transition milk stored at 4 °C, cell viability and acidity were maintained at acceptable levels throughout the 60-d storage period. The viability of L. plantarum in fermented transition milk stored at 25 °C remained acceptable up to 50 d and minimum pH values were analyzed after 38 d of storage and maximum acidity levels after 56 d. Considering these results, transition milk may be preserved by L. plantarum fermentation as a substitute for milk in the artificial feed for calves as functional food.

A avalição dos parâmetros microbiológicos de alimentos representa indícios da qualidade e segurança de suas matrizes, que podem oferecer riscos e causar danos à saúde do consumidor quando os valores observados estão incompatíveis com os critérios apropriados. O leite e seus produtos derivados estão frequentemente relacionados à intoxicação estafilocócica, uma vez que cepas enterotoxigênicas de Staphylococcus spp. é citado como um dos causadores de mastite bovina. Como forma de elucidar alternativas eficazes de impedir o desenvolvimento de S. aureus em matriz láctea, produziram-se queijos, adicionados de combinações de uma cepa padrão S. aureus FRI361 produtora de enterotoxina C, e duas bactérias ácido-láticas (BAL) Lactobacillus plantarum e Lactobacillus rhamnosus isoladas de soro-fermento de queijarias cadastradas da Canastra em Minas Gerais e identificadas proteômicamente pela técnica de MALDI-TOF. Os queijos Minas Frescal, produzidos com cepas de BAL, foram capazes de reduzir a contagem de S. aureus do 1º ao 14º dia após a produção, nos tratamentos que apresentaram pelo menos uma BAL junto do patógeno. A presença de bactérias ácido-láticas mostrou potencial ação inibidora frente ao S. aureus no queijo Minas Frescal, podendo contribuir para a melhoria da qualidade sanitária de queijos frescos.