Staphylococcus aureus causes food intoxication and can become resistant to a large number of drugs. Thus, there is a growing interest in understanding the mechanisms involved in the adaptation of bacterial cells to environmental stresses or to antimicrobial agents. In this context, we evaluated the cinnamaldehyde (CIN) MBC for two contaminating food strains of S. aureus (GL 5674 and GL 8702) and tested the hypothesis that the exposure of these strains to sublethal concentrations of CIN and pH could increase their resistance to this antimicrobial, to acid stress and also to stress at high temperatures. Thus, the ability of the strains to adapt to CIN and acid stress was evaluated, as well as the cross adaptation between acid stress and CIN. The strains GL 5674 and GL 8702 of S. aureus are sensitive to CIN in MBCs of 0.25% and 0.5% respectively, proving the antibacterial potential of this compound, but we proved the hypothesis of homologous adaptation to CIN. The strains grew in concentrations higher than the MBC after being previously exposed to sublethal concentrations of CIN. It was also observed heterologous adaptation of the strains, which, after exposure to the minimum pH of growth, were able to grow in concentrations greater than the MBC of CIN. GL 5674 showed greater adaptive plasticity, considerably reducing its minimum inhibitory pH and increasing its MBC after adaptation. Our results show a positive effect of adaptation to CIN, on the resistance of S. aureus (p <0.0001) to CIN, at a temperature of 37 ° C. However, in the absence of adaptation, the presence of CIN in S. aureus cultures maintained at 37 ° C, associated with increased exposure time showed an efficient bactericidal effect. Our results call attention to the conscious use of CIN as an antimicrobial agent and presents the possibility of using CIN, associated with the temperature of 37 ºC and the exposure time of 35 min, as a promising measure for the elimination of pathogenic strains .

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The use of plant growth promoting bacteria (PGPB) that can solubilize phosphorus (P) has shown potential to improve nutrient availability in many crops such as soybean. This research aimed to evaluate agronomic efficiency and phosphorus solubilization through Bradyrhizobium japonicum and product to be registered Pseudomonas fluorescens (BR 14810) in soybean, at seed and leaf-spray inoculation. Four experiments with soybean (2020/21 crop) were installed in the following locations in the State of Goiás: Experimental Area of the Goiano Federal Institute, in Rio Verde, Bela Vista Farm, in Indiara, Bauzinho Farm, in Rio Verde, and Cachoeira Farm, in Doverlândia. The B. japonicum was inoculated in the seed of all treatments. It was tested three phosphate fertilization doses: 0, 50, and 100% recommended P dose, with and without P. fluorescens, at seed treatment and leaf-spray inoculation. The use of inoculation with P. fluorescens and B. japonicum increases nitrogen (N) content in grains and total N. The P content in dry mass, grains and total are increased using P. fluorescens and B. japonicum, confirming the ability to solubilize phosphates. Inoculation with P. fluorescens and B. japonicum is efficient for increasing shoot dry mass and productivity, can be used as a sustainable soybean management technology. Leaf-spray was more efficient than inoculation in seed treatment and can be used as an alternative mode of application. The results demonstrated that the product under test (P. fluorescens-BR 14810) can be used associated with B. japonicum, in ST or leaf-spray, resulting in increases of agronomic parameters and soybean yield.