“…In soybean, problems related to nodulation were attributed to the predominance of antibiotic producing actinomycetes (25). Tests to evaluate the antimicrobial spectrum (20) indicated that the actinomycetes isolates influenced the capacity of lineages of Bradyrhizobium spp to compete for soybean nodulation sites. On the other hand, rhizobium in seeds of beans co-inoculated with Bacillus subtilis presenting biological control capacity against soil fungi did not interfere in the growth promotion capacity (8), showing that the development of mixed inoculants could be useful to promote growth (rhizobium effect by nitrogen contribution) and to protect plants from diseases (Bacillus effect by inhibition of pathogenic fungi).…”
Emphasis has been given on selection of micro-organism for biological control. However, in order to evaluate the biological control potential of a great number of micro-organisms in a small period of time it is necessary to develop an efficient bioassay. Seven hundred and sixty bacterial isolates from different habitats, were selected for compatibility with Rhizobium leguminosarum bv. phaseoli (SEMIA 4077 e SEMIA 4080). Among them 596 isolates were ineffective against both rhizobia. Bean seeds immersed in suspension of each one of these isolates were agitated for 5 hours at 10 o C and sowed in non-sterilized soil. The plants were kept in greenhouse. After the development of cotyledonary and primary leaves, these were removed and bioassayed for Xanthomonas axonopodis pv. phaseoli (XAP) control. In the cotyledonary leaves, it was observed that the isolate DFs093 offered 100% control, DFs041 and DFs1297 offered 90% and DFs490, DFs769, DFs831, DFs842 and DFs843 offered 80% control. In the primary leaves, the DFs482 isolated offered 100% and the DFs080, DFs348, DFs513, DFs622, DFs769, DFs842 and DFs912 offered 80% of XAP control.
“…In soybean, problems related to nodulation were attributed to the predominance of antibiotic producing actinomycetes (25). Tests to evaluate the antimicrobial spectrum (20) indicated that the actinomycetes isolates influenced the capacity of lineages of Bradyrhizobium spp to compete for soybean nodulation sites. On the other hand, rhizobium in seeds of beans co-inoculated with Bacillus subtilis presenting biological control capacity against soil fungi did not interfere in the growth promotion capacity (8), showing that the development of mixed inoculants could be useful to promote growth (rhizobium effect by nitrogen contribution) and to protect plants from diseases (Bacillus effect by inhibition of pathogenic fungi).…”
Emphasis has been given on selection of micro-organism for biological control. However, in order to evaluate the biological control potential of a great number of micro-organisms in a small period of time it is necessary to develop an efficient bioassay. Seven hundred and sixty bacterial isolates from different habitats, were selected for compatibility with Rhizobium leguminosarum bv. phaseoli (SEMIA 4077 e SEMIA 4080). Among them 596 isolates were ineffective against both rhizobia. Bean seeds immersed in suspension of each one of these isolates were agitated for 5 hours at 10 o C and sowed in non-sterilized soil. The plants were kept in greenhouse. After the development of cotyledonary and primary leaves, these were removed and bioassayed for Xanthomonas axonopodis pv. phaseoli (XAP) control. In the cotyledonary leaves, it was observed that the isolate DFs093 offered 100% control, DFs041 and DFs1297 offered 90% and DFs490, DFs769, DFs831, DFs842 and DFs843 offered 80% control. In the primary leaves, the DFs482 isolated offered 100% and the DFs080, DFs348, DFs513, DFs622, DFs769, DFs842 and DFs912 offered 80% of XAP control.
“…Entre os fatores bióticos Pereira et al (1999) destacam as populações de actinomicetos na comunidade microbiana de solos tropicais, pelo potencial dos mesmos em produzir antibióticos pois cerca de 85% dos antibióticos conhecidos são produzidos por esses micro-organismos (Gottlieb, 1973).…”
Section: Introductionunclassified
“…Entre esses efeitos antagônicos estão aqueles causados por bactérias do grupo dos rizóbios (Pereira et al, 1999), bactérias diversas resistentes e sensíveis à meticilina (Satheeja & Jebakumar, 2011), fungos micorrízicos arbusculares (Moreira & Siqueira, 2006) e aqueles causados sobre o sistema simbiótico rizóbio -FMA -planta (Pereira et al, 1991).…”
RESUMOIsolados de actinomicetos e de fungos micorrízicos arbusculares foram avaliados em sistemas de inoculação conjunta in vivo, em plantas de soja inoculadas com rizóbios, com a finalidade de se observar interações microbianas. A pesquisa foi realizada no Centro Nacional de Pesquisa de Agrobiologia (Embrapa CNPAB). Foram utilizados, como substrato, solo da série Itaguaí (textura média) misturado com areia de rio na proporção 1:1 (v:v), com adição de isolados de actinomicetos (ACT-78 e ACT-370); estirpes de rizóbios (Bradyrhizobium elkanii -BR 29 e Bradyrhizobium japonicum -BR 33) e fungos micorrízicos arbusculares (Gigaspora margarita e Glomus clarum). Os resultados revelam que a inoculação com os fungos micorrízicos arbusculares influenciou de modo expressivo as variáveis de crescimento, nodulação e densidade de actinomicetos na rizosfera de soja, que apresentaram valores maiores do que as plantas sem o inóculo fúngico. Houve efeitos sinergísticos e antagônicos dos fungos micorrízicos arbusculares com os actinomicetos e com rizóbios.
Palavras-chave: fixação biológica de nitrogênio, interações microbianas, sinergismo, antagonismoInteractions between arbuscular mycorrhizal fungi Rhizobium and actinomycetes in the rhizosphere of soybean ABSTRACT Actinomycete isolates and arbuscular mycorrhizal fungi were evaluated in vivo using jointly inoculation systems with soybean plants inoculated with rhizobia, with the aim to observe microbial interactions. The study was carried out at the National Center of Agrobiologic Research (Embrapa CNPAB). Soil of the Itaguai series (medium texture) was used as substrate mixed with river sand in proportion 1:1 (v:v), adding actinomycete isolates (ACT 78 and ACT 370), rhizobia strains (Bradyrhizobium elkanii -BR 29 and Bradyrhizobium japonicum -BR 33), and arbuscular mycorrhizal fungi (Gigaspora margarita and Glomus clarum). The results revealed the effect of the arbuscular mycorrhizal fungi addition with significant and expressive influence on growth parameters, nodulation and density of actinomycete isolates on the soybean rhizosphere which showed greater values compared with fungi uninoculated plants. Synergistic and antagonistic effects were observed between the arbuscular mycorrhizal fungi with actinomycetes isolates and rhizobia strains.
“…No entanto, a presença da microbiota nativa do solo, que é geralmente competitiva e bem adaptada, pode reduzir os benefícios dessa simbiose com rizóbios, mesmo utilizando-se cepas altamente eficientes (PEREIRA et al, 1999;PEREIRA et al, 2013).…”
unclassified
“…Entre os fatores bióticos destacam as populações de actinobactérias devido ao potencial de produzir antibióticos. Vários estudos na literatura sugerem o efeito antagônico de actinobactérias sobre outros microrganismos (MOKNI-TLILI et al, 2013) e, particularmente, sobre as bactérias diazotróficas (LIMA et al, 2017;PEREIRA et al, 1999;PEREIRA et al, 2013).…”
RESUMOExistem várias interações ocorrendo no solo que determinam as propriedades do mesmo como um meio para atividade e crescimento de plantas e microrganismos. Há diversos tipos diferentes de microrganismos na rizosfera interagindo com os outros organismos do solo e com as raízes das plantas. As actinobactérias são de ocorrência universal na natureza e são amplamente distribuídas em ambientes naturais. As bactérias diazotróficas, também chamadas de rizóbios, realizam o processo de fixação biológica do nitrogênio (FBN) sendo uma importante fonte de nitrogênio para o solo. Dados da literatura relatam antagonismo das actinobactérias sobre vários microrganismos do solo incluindo os rizóbios. As interações bióticas conduzem a processos ecológicos e evolutivos fundamentais, porém a sua intensidade, direção e frequência são sensíveis às mudanças climáticas. O semiárido brasileiro é uma região caracterizada por baixa precipitação anual, temperaturas elevadas e vegetação caducifólia. Os recursos nos solos dessa região são geralmente limitantes para os microrganismos, o que favorece a competição.
PALAVRAS-CHAVE: Antagonismo, Coexistência, Microrganismos do solo
BIOTIC INTERACTIONS BETWEEN ACTINOBACTERIAS AND RHIZOBIA IN SOILS OF THE BRAZILIAN SEMI-ARID REGIONABSTRACT There are several interactions occurring in the soil that determine its properties as a medium for the activity and growth of plants and microorganisms. There are different types of microorganisms in the rhizosphere interacting with other soil organisms and with plant roots. Actinobacteria universally occur in nature and are widely distributed in natural environments. Diazotrophic bacteria, also known as rhizobia, perform the biological nitrogen fixation process (BNF) being an important source of nitrogen for the soil. The scientific literature reports antagonism of actinobacteria on various soil
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