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    Dinâmica sazonal do resistoma em Staphylococcaceae e matrizes ambientais de fazendas leiteiras no sudeste do Brasil
    (Universidade Federal de Viçosa, 2026-02-27) Santos, Thifani Ramos; Ribon, Andréa de Oliveira Barros; http://lattes.cnpq.br/8110741498986149
    A resistência antimicrobiana é um desafio global, e ambientes de produção animal atuam como reservatórios de genes de resistência. Este estudo investigou a prevalência e distribuição de genes de resistência em Staphylococcaceae isoladas de fazendas leiteiras em Viçosa, MG, considerando a sazonalidade como fator associado. Seis campanhas de amostragem foram realizadas em três propriedades entre julho/2024 e agosto/2025, abrangendo as estações seca e chuvosa. Amostras de cama de vacas em lactação, cama de novilhas, esterco, serragem, silagem, solo cultivado e solo de pastagem foram coletadas. O isolamento bacteriano foi realizado em ágar sal manitol, com identificação por MALDI-TOF MS. A suscetibilidade antimicrobiana foi determinada por microdiluição em caldo para sete antibióticos, e a detecção de genes de resistência em isolados e DNA ambiental foi realizada por PCR. Foram obtidos 26 isolados de Staphylococcaceae, predominantemente Mammaliicoccus sciuri (38,5%) e Staphylococcus xylosus (26,9%), além de S. arlettae, S. simulans, S. piscifermentans e S. chromogenes. As camas foram os principais reservatórios, concentrando 65,4% dos isolados. Observou-se elevada resistência aos beta-lactâmicos penicilina, amoxicilina e ampicilina, enquanto gentamicina e tetraciclina permaneceram ativas contra todos os isolados. A análise molecular revelou maior frequência de detecção na estação seca, onde 50% dos isolados (6/12) apresentaram amplificação para pelo menos um gene de resistência, em comparação ao período chuvoso, que apresentou três ocorrências gênicas totais distribuídas entre os 14 isolados. Os genes detectados concentraram-se nos associados às tetraciclinas (tetK e tetM) e ao macrolídeo ermC. Co-ocorrência de genes foi observada em S. xylosus, com detecção simultânea de tetK, tetM e ermC em isolados da estação seca. Os genes aac(6')-aph(2") e vanA não foram detectados. No DNA ambiental, ermB, ermC e tetA foram consistentemente detectados no esterco em todas as fazendas e estações, indicando que esta matriz funciona como reservatório persistente de genes de resistência. Na cama, observou- se maior variabilidade: ermB alternou entre fazendas e estações, ermC esteve ausente na seca e presente em duas fazendas na chuvosa, e tetA foi detectado apenas em uma fazenda na chuvosa. Os resultados demonstram que a prevalência e distribuição de genes de resistência em Staphylococcaceae em fazendas leiteiras de Viçosa apresentam tendência de variação associada à sazonalidade, com maior detecção na estação seca. A abordagem integrada, combinando isolamento bacteriano e análise de DNA ambiental, permitiu capturar diferentes dimensões do resistoma no agroecossistema. Estes achados reforçam a necessidade de incorporar a variabilidade temporal em programas de monitoramento e em estratégias de mitigação da resistência antimicrobiana sob a perspectiva de Saúde Única. Palavras-chave: resistência bacteriana; saúde única; sazonalidade
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    Derivative spectrophotometry for NO3- determination in sanitary sewages
    (Revista Engenharia na Agricultura, 2020) Mesquita, Tayane Cristiele Rodrigues; Silva, Pamela Lais Cabral; Vaz, Lucas Rafael Lommez; Borges, Alisson Carraro
    The objective of this study was to observe the feasibility of using the UV spectrophotometric method of the second derivative in the determination of nitrogen in the form of nitrate in sanitary sewers, since this method is indicated for water with low content of organic matter. Therefore, the results obtained in that method were compared with the salicylate methodology. The Mann-Whitney test showed a significant difference (α = 5%) between the results obtained in both methods. However, when compared, the difference between them was less than 0.25 mg L-1in half of the observations. Despite this significant difference, the use of the second derivative method for sanitary sewage samples showed satisfactory performance.
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    Influence of temperature and altitude on the expansion of coffee crops in matas de Minas, Brazil
    (Revista Engenharia na Agricultura, 2020) Oliveira, Karine Rabelo; Ferreira, Williams Pinto Marques; Fonseca, Humberto Paiva; Souza, Cecília Fátima
    Coffee is among the most significant products in Brazil. Minas Gerais is the largest state producer of Arabica coffee. Coffee activity has excellent growth potential, which justifies the identification of new areas for expansion of the culture. This study aimed to determine factors that affect the spatial distribution of coffee plantations the most, as well as to identify areas with a greater aptitude for its expansion in the region of the Matas de Minas (63 municipalities). The MaxEnt software was used to elaborate a model capable of describing the area with the highest potential for estimating the probability of coffee adequacy. The elaboration of the model considered the records of occurrence, climatic and topographic variables of Matas de Minas, the second largest state producing region. The area under the curve (AUC), the omission rate and the Jackknife test were used for validation and analysis of the model. The model was accurate with an AUC of 0.816 and omission rate of 0.54% for the ‘test’. It was identified that the potential distribution of coffee in Matas de Minas is determined by changes in the annual maximum temperature, although it did not generate a significant gain when omitted, accounting for a considerable loss in the model. However, the most influential variables on the delineation of distribution were, the altitude and the annual average temperature. The most favorable areas for expansion of coffee culture in the Matas de Minas were found in the vicinity of the region of Alto Caparaó. Abbreviations used: A1 (altitude); A2 (maximum annual temperature); A3 (annual minimum temperature); BIO 1 (annual average temperature 1); BIO 4 (temperature seasonality), BIO 12 (annual precipitation); BIO 15 (precipitation seasonality); csv (comma-separated values); AUC (area under the curve).
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    Comparison between estimation methods of reference evapotranspiration in Bom Jesus da Lapa, BA
    (Revista Engenharia na Agricultura, 2020) Costa, Taiara Souza; Santos, Robson Argolo dos; Sales, Ramon Amaro de; Nogueira, Aldnira Tolentino; Santos, Rosangela Leal
    Among the reference evapotranspiration (ETo) equations, the FAO-56 Penman-Monteith (PM FAO-56) model is considered the most accurate, but this model requires a greater amount of meteorological data. On the other hand, there are other methods that require fewer variables and have shown good precision according to the location. The objective of this work was to evaluate the efficiency of four methods for estimation of daily ETo, comparing them with FAO-56 PM equation in Bom Jesus da Lapa, Bahia, Brazil. To do so, a dataset from 2010 to 2017, acquired at the National Institute of Meteorology (INMET), was used. The models were analyzed by means of statistical indicators: Willmott’s concordance index, root mean square error (RMSE), mean bias error (BIAS), coefficient of determination “R²”, correlation coefficient “r” and coefficient of confidence “c”, in addition to the classification of the coefficient of confidence. The results obtained show that Hargreaves and Samani equation was the only method classified as “good” and is recommended. While the models of Camargo, Priestley and Taylor and Benevides and Lopes are not recommended to calculate ETo in the municipality.
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    Quality control of pneumatic spraying in tomato
    (Revista Engenharia na Agricultura, 2020) Teixeira, Cleonice Campos; Teixeira, Mauri Martins; Fernandes, Haroldo Carlos; Vitória, Edney Leandro da; Cecon, Paulo Roberto; Silva, Derly José Henriques da
    Tomato is a vegetable of great importance on the national scene. One of the problems of this culture is the great susceptibility to attack by pests and diseases. Thus, one of the most used practices is chemical control with phytosanitary products. The objective of this study was to evaluate the technical parameters of pneumatic spraying in tomato culture, through the study of the volumetric index and the population of spray droplets, aiming to reduce the spray volume, obtain the best efficiency and the social and environmental safety of the applications. The study of the droplet population was performed using water-sensitive paper labels. These labels were placed in the canopies of the tomato plants at three different heights and two positions. The sprays were made using a pneumatic backpack sprayer. After applying the syrup (dye + water), the water-sensitive paper labels were collected and subjected to the coverage and droplet density analyses by the computer program “CIR” version 1.5. The pneumatic sprayer proved to be efficient for the application of phytosanitary products in the tomato. The percentage of the target covered area ranged from 2.1 to 8.3% for volumetric indices as a function of thirds and positions, whereas the density of droplets ranged from 145.4 to 690.1 drops cm-2 for thirds and positions of the tomato plants evaluated. Finally, the volumetric index of 5 mL m-3, with a consequent spray volume of 50 L ha-1, met the parameters of a quality spray.