In this study, we evaluate spatial and temporal variations of the water's quality used in rice fields. Every 15 days during the different phases of cultivation of the rice-vegetative, reproductive, and maturity-samples were collected from the main irrigation channel, from the surface water in the field, and from the excess-water drainage channel. The differences in the values of 13 variables were analyzed by the analysis of variance system and by the Principal Component Analysis (PCA) technique. The results demonstrate that the values observed for the presence of total coliforms, heat-tolerant coliforms, and pH were higher in the irrigation water and that the calcium and magnesium components were greater in the drainage water. The PCA results indicate that three groups of variance exist and that these three account for 77 % of the observed variances. The first principal component, (39 % of the variances), includes the variables pH, phosphorus, potassium, carbon, and turbidity; the second (28.1 %), calcium, magnesium, and conductivity; while the third accounts for only 9.9 % of the variation and incorporates the variable biological thermotolerant coliforms. The spatial pattern resulting from the distribution of the sampling locations as regards the first two principal components indicates a difference between the irrigation and drainage waters. The variables of the first and third items (except for the turbidity in the second component) reach higher values in the irrigation water, while the variables associated with the second component have higher values in the drainage water. The information provided is important for the analysis of the influence exercised by plantation management decisions on the microbiological, physical, and chemical quality of the water. The results confirm the ability of paddy rice field to filter out some of the chemicals and coliforms from the irrigation water as it passes through the agro ecosystem.

This work presents bibliographic data on the role and function of microbial diversity. The increasing use of probiotics and prebiotics foods has led to the studies on their actual functions in the human body. It is known that in the environment, microorganisms are extremely important in recycling of nutrients, balance of trophic chains, vital physiological activities in the plants and animals, as well as the conservation of natural habitats. In human food, these microscopic organisms contribute from flavoring products to the synthesis of antimicrobial substances and vitamins essential to living beings.

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ResumoA interação bactéria-solo-planta tem sido muito usada com o intuito de apoiar a biotecnologia de alimentos. As bactérias encontradas no solo são extremamente diversas, sendo modificada rapidamente à medida que novos nutrientes são disponibilizados ou os existentes são esgotados. O arroz é um dos alimentos mais consumidos no mundo, cerca de 2,4 bilhões de pessoas o utilizam como base na sua alimentação. Sabe-se que a dieta é um dos maiores determinantes para a persistência de certas bactérias no trato gastrointestinal, porque ela proporciona nutrientes, não somente para o hospedeiro, mas também para as bactérias que nele estão. Neste contexto, o objetivo deste trabalho foi avaliar a abundância de bactérias presentes no solo de uma cultivar de arroz, considerando diferentes regiões e diferentes fases fenológicas das plantas. As coletas foram realizadas nas cidades de Santo Antônio da Patrulha, RS e Charqueadas, RS em arrozais de cultivo mínimo, do tipo Puitá INTA-CL, no ano agrícola 2013/14. As amostras do solo foram realizadas em triplicata e em locais aleatórios das lavouras. Foram realizadas coletas no período de pré-plantio, fase vegetativa, reprodutiva e maturação. A abundância foi verificada através de contagem de Unidades Formadoras de Colônias (UFCs) bacterianas em placas de ágar nutriente, 24 horas depois do repique de cada amostra coletada a campo. Os resultados da abundância apresentaram diferenças significativas