Studies on the survival of pathogenic microorganisms in the soil after use of wastewater for fertilization of agricultural crops report the effects of moisture, pH, organic matter, and soil temperature on microorganisms. There are few studies that assess the survival of these microorganisms in the rhizosphere of plants fertilized with wastewater. Thus, the aim of this study was to quantify the number of fecal coliforms and rhizobacteria (fluorescent Pseudomonas spp., Bacillus spp,) in the rhizosphere of winter and summer crops fertilized with wastewater. In the experiment, we used 20 plots, and each plot occupied an area of 200 m². The treatments used in the winter crop consisted of uncultivated plots and single crops of wheat, triticale, black bean, and intercropped black bean/wheat. In the summer season, we used uncultivated plots and single crops of corn, sunflower, bean, and intercropped bean/corn. The experiment was conducted in a randomized block design with five treatments and four replications. Soil samples from the rhizosphere for microbiological analyses were collected at the flowering stage of the crops at a depth of 0.00-0.20 m. Plants stimulated fluorescent Pseudomonas spp. and Bacillus spp. in the rhizosphere, with average scores of 7.9 and 6.9 log CFU g -1 of dry soil, respectively, whereas in bare soil, these scores were 6.7 and 5.8 log CFU g -1 of dry soil for these rhizobacteria groups. However, this stimulating effect was not seen for fecal coliforms, which had an average score of 31.7 × 10 3 MPN g -1 of dry soil in the uncultivated area and 20.0 × 10 3 MPN g -1 of dry soil in crop areas. Overall, the numbers of rhizobacteria colonies in the rhizosphere soil under intercropping were higher than those observed in the rhizosphere soils of single winter and summer crops. Therefore, the presence of plants enhances the development of rhizobacteria and changes the balance among the species of microorganisms in the soil microbial community fertilized with wastewater.

RESUMOA aplicação do composto de lodo de esgoto em áreas agrícolas pode promover alterações nos atributos microbianos do solo. Assim, há necessidade de se avaliar o impacto da adição do composto sobre a atividade microbiana do solo. O presente trabalho objetivou avaliar a alteração nos atributos microbianos de um solo fertilizado com diferentes doses de composto de lodo por meio da medida de liberação de CO 2 e a contagem de bactérias e fungos. O experimento foi realizado em condição de laboratório, com jarros respirométricos contendo em seu interior amostras de solo misturadas com composto nas doses de 0; 20; 40; 60 e 80 Mg ha -1 . A liberação de CO 2 do solo foi medida diariamente durante os 28 dias de incubação. Após a incubação, as amostras de solo foram retiradas dos jarros e submetidas à contagem de bactérias e fungos e à determinação da composição química do solo. Os tratamentos correspondentes às doses do composto foram dispostos em delineamento completamente casualizado com quatro repetições. A liberação de CO 2 e o número de bactérias e fungos aumentaram significativamente com as doses do composto devido ao fornecimento de substrato energético e nutrientes proporcionados pelo composto. A medida de liberação de CO 2 indicou que a doses de composto acima de 20 Mg ha -1 ocasionou impactos significativos sobre a atividade microbiana do solo.Palavras-chave: atividade microbiana, bactérias, fungos. Soil microbial attributes treated with composting of sewage sludge ABSTRACTThe use of sludge composting in agricultural areas alters the microbial functions. In this context it is necessary to evaluate the impact of composting addition on microbial activities in the soil. This study evaluated the alteration of microbial attributes of a soil fertilized with sewage sludge compost by measuring the CO 2 release rates and counting bacteria and fungi numbers. This experiment was conducted in laboratory using respirometric jars that contained samples of soil mixed with different doses of compost: 0; 20; 40; 60 and 80 Mg ha -1 , and CO 2 release was quantified daily during the 28 days of incubation when the samples were removed from the jars and bacteria and fungi quantities were counted. The treatments corresponding to each dose of the composting were arranged in completely randomized design with four replications. The CO 2 release and the quantity of bacteria and fungi increased with additional doses of the compound. This occurred as a result of supplying energetic substrate and