Non-symbiotic diazotrophic bacteria are amongst the most important functional groups of soil-dwelling microorganisms. These bacteria contribute to plant growth predominantly through biological N2 fixation. Here, we evaluated the density and diversity of non-symbiotic diazotrophic bacteria in soils taken from diverse land use systems (LUS) in Amazonia using nitrogen-free media. A total of 30 soil samples were collected from the following LUS: pristine forest, young secondary forest, old secondary forest, agroforestry, agriculture and pasture. Bacterial density was evaluated by the most probable number (MPN) method utilizing N-free semi-solid media with varied compositions (JNFb, NFb, LGI and Fam). Individual isolates were characterized by colony and cellular morphology as well as total protein profiles and nitrogenase activity. Isolate genotypes were determined by partial 16S rDNA sequences. No typical diazotrophic growth in the JNFb medium was observed. Bacterial densities in the NFb medium were higher in the agriculture and agroforestry soil samples. In LGI and Fam media, bacterial densities were highest in the pasture soil samples. Overall, 22 isolates with high phenotypic diversity were obtained. Eleven isolates exhibited nitrogenase activity. Sequences of 16S rDNA genes of 14 out of 19 isolates had similarities below 100 % with known nitrogen-fixing species. Isolates were identified as belonging to the Burkholderia, Enterobacter, Serratia, Klebsiella, and Bacillus genera. A higher number of isolates from pasture soil samples were isolated, with the majority of these belonging to the Burkholderia and Bacillus genera. Among the isolates, unknown sequences were obtained, possibly indicating new species. Taken together, these data demonstrate that Fam, NFb, and LGI semi-solid media allowed the growth of diazotrophic bacteria belonging to different phylogenetic lines.

O futebol apresenta uma séria de situações geradoras de estresse. O momento pré-competitivo é altamente gerador de estresse. O alongamento pode contribuir para diminuir estes efeitos negativos do estresse. O objetivo deste estudo foi verificar os efeitos do alongamento no estresse pré-competitivo de jogadores de futebol. Participaram deste estudo 17 atletas juvenis, distribuídos em dois grupos: Grupo Controle (GC) e Grupo Alongamento (GA). Todos responderam ao TEF e, em seguida, o GA praticou 30 minutos de alongamento enquanto o GC vivenciou as situações habituais sem realização de atividade física. Logo após, os dois grupos responderam novamente ao TEF, sendo invertidos os grupos na partida seguinte. As situações “Dormir mal a noite anterior ao jogo” e “Ser prejudicado pelos juizes” foram avaliadas com respostas mais negativas enquanto “Cobrança de si mesmo para ganhar” e “O time adversário é o favorito” foram avaliadas como respostas mais positivas. O GA obteve aumento no número de avaliações positivas comparado ao GC, diminuição no nulo e diminuição na resposta -1 e -3, enquanto o GC obteve diminuição no valor -2. Conclui-se que a situação pré-competitiva modifica negativamente a avaliação dos atletas enquanto o alongamento interfere positivamente frente à avaliação das situações estressoras em jogadores juvenis.

Soccer show a series of stress-generated situations. The streatching may contribut to decrease this stress negative effects. The pre-competitive moment is stress generator. Yhe objetive of this study was to verify the effects of strectch on pre-competitive stress in soccer players. To this, 17 juvenile soccer players were allocated into two groups: control group (CG) and strecth group (SG). All participants responsed to TEF (Stress soccer test) and GA stretching during 30 minutes while GC not realized any physical activity. After this, both groups responded to TEF and was inverted in the next game. The situations “sleep badly on previous night” and “Be damaged for arbitrator” was avaliated with more negative reponses while “ Himself charged to win” and “ The adversary is the favourite” was was avaliated with more positive reponses. SG showed positive avaliations increased copared to CG, decreased on nule response and decreased on -1 and -3 responses. GC showed decrease in -2 responses. Concluded that pre-competitive situation modify negatively the athletes avaliation while the strecth interfere positively in front the avaliation of stressor situations in juvenile players.

A soja, atualmente, é a leguminosa de maior expressão econômica no Brasil. Em razão da demanda crescente no mercado internacional, a cultura encontra-se em larga expansão em todo território brasileiro. Em alguns ensaios realizados em solos ácidos brasileiros, sob sistema de plantio direto, essa cultura tem mostrado baixa resposta à aplicação de calcário. Porém, a acidez é um dos fatores que limitam a eficiência da simbiose rizóbio-leguminosas. Para contornar esses problemas, poderiam ser utilizadas estirpes tolerantes à acidez do solo ou induzir tolerância nas estirpes já utilizadas. Em alguns trabalhos, tem-se demonstrado indução de tolerância à acidez quando a bactéria é previamente exposta a pH ácido. Assim, objetivou-se com este trabalho verificar o crescimento de Bradyrhizobium elkanii estirpe Br 29 em meios de cultura sob diferentes condições de pH inicial. Foram realizados dois experimentos com dois meios de cultivo diferentes, em que se variou o pH inicial (6,8; 6,0; 5,5). Foram avaliados: o crescimento da estirpe, pela contagem do número de unidades formadoras de colônia (UFC) e por densidade ótica, assim como as mudanças do pH nos meios. As curvas de crescimento obtidas variaram de acordo com o pH inicial e com a composição do meio de cultura. Com base no número máximo de UFC.mL-1, para o meio Lorda & Balatti modificado, o melhor pH foi 6,0 e, no meio Lopreto, o melhor pH foi 5,5. O melhor crescimento em pH mais baixo (5,5) está associado à maior produção de exopolissacarídeo.

Currently soybean is the most economically important legume crop in Brazil. Due to its profitability soybean is being widely spread out all over the national territory. Some assays have shown low response of this crop to liming in acid Brazilian soil, under no-till age systems. Acidity is one of the factors that limit the efficiency of the symbiosis rhizobia - legumes. This problem could be solved if acid tolerant strains were obtained or if tolerance to acidity could be induced. Some papers demonstrated induced tolerance to acidity when the bacterium is previously exposed to a slightly acid pH. The aim of this study was to verify the growth of Bradyrhizobium elkanii strain Br 29 in culture media with different pH values (6.8; 6.0; 5.5). Two experiments were carried out with two different culture media varying mainly regarding initial pH. Strain growth, by optical density and colony forming units (CFU) number, and pH medium modification were evaluated. Growth curves varied either in accordance with pH or culture media composition. Growth based on maximum number of CFU.mL-1 was better at pH 5.5 in Lopreto medium and at pH 6.0 at Lorda and Balatti medium. Better growth on lowest pH (5.5) was related to greater exopolyssacaride production.