ABSTRACT
Abstract High world population and the increase in global food demands results in an indiscriminate use of chemical fertilizers by farmers, causing soil deterioration and other environmental problems. In recent years there has been a collective concern to preserve the environment through sustainable and environmentally friendly techniques. Plant growth-promoting bacteria (PGPB) are widely known to benefit plants in a sustainable manner, reducing chemical fertilizers application. Many studies have shown that these bacteria not only improve crop yields but also its quality, increasing certain nutrients and molecules that are important for human health such as aminoacids, proteins, vitamins, flavonoids, antioxidants, essential oils, among others. This work compiles recent information of PGPB as an alternative of chemical fertilizer for improving crop yields and plant metabolites production.
El incremento acelerado de la población mundial que conlleva al aumento en la demanda de alimentos; ha ocasionado el uso indiscriminado de fertilizantes químicos por parte de los agricultores, provocando así el deterioro del suelo y con ello los subsecuentes problemas ambientales. En los últimos años ha surgido la preocupación colectiva de preservar el medioambiente a través del uso de técnicas sostenibles y ambientalmente amigables. Las bacterias promotoras de crecimiento vegetal (PGPB) son ampliamente conocidas por incrementar el crecimiento y desarrollo de las plantas de manera sostenible permitiendo así la reducción de la aplicación de fertilizantes químicos. Muchos estudios han demostrado que estas bacterias no solo mejoran el rendimiento de los cultivos sino también la calidad de estos, aumentando ciertos nutrientes y moléculas que son importantes para la salud del ser humano que los consume como aminoácidos, proteínas, vitaminas, flavonoides, antioxidantes, aceites esenciales, entre otros. Este trabajo recopila información reciente de las PGPB como alternativa a los fertilizantes químicos para la mejora en el rendimiento de los cultivos y la producción de metabolitos en las plantas.
ABSTRACT
ABSTRACT Mangroves are ecosystems located in the transition zone between land and sea that serve as a potential source of biotechnological resources. Brazil's extensive coast contains one of the largest mangrove forests in the world (encompassing an area of 25,000 km2 along all the coast). Endophytic bacteria were isolated from the following three plant species: Rhizophora mangle, Laguncularia racemosa and Avicennia nitida. A large number of these isolates, 115 in total, were evaluated for their ability to fix nitrogen and solubilize phosphorous. Bacteria that tested positive for both of these tests were examined further to determine their level of indole acetic acid production. Two strains with high indole acetic acid production were selected for use as inoculants for reforestation trees, and then the growth of the plants was evaluated under field conditions. The bacterium Pseudomonas fluorescens (strain MCR1.10) had a low phosphorus solubilization index, while this index was higher in the other strain used, Enterobacter sp. (strain MCR1.48). We used the reforestation tree Acacia polyphylla. The results indicate that inoculation with the MCR1.48 endophyte increases Acacia polyphylla shoot dry mass, demonstrating that this strain effectively promotes the plant's growth and fitness, which can be used in the seedling production of this tree. Therefore, we successfully screened the biotechnological potential of endophyte isolates from mangrove, with a focus on plant growth promotion, and selected a strain able to provide limited nutrients and hormones for in plant growth.
Subject(s)
Bacteria/isolation & purification , Trees/microbiology , Acacia/microbiology , Endophytes/isolation & purification , Phylogeny , Bacteria/classification , Bacteria/genetics , Bacteria/metabolism , Trees/growth & development , Brazil , Acacia/growth & development , Wetlands , Endophytes/classification , Endophytes/genetics , Endophytes/metabolism , Indoleacetic Acids/metabolismABSTRACT
ABSTRACT: The aim of this study was to evaluate the biochemical responses of maize, under saline stress, inoculated with Bacillus subtilis. Four levels of salinity were assessed: 0mM, 50mM, 100mM, and 200mM of sodium chloride (NaCl). Saline conditions influenced negatively maize growth. However, the inoculation of B. subtilis improved the plant growth at highest level of NaCl. Chlorophyll content decreased while proline increased in inoculated plants submitted to highest salt levels. Also, B. subtilis increased the relative water content in leaves. B. subtilis improves the plant growth under salinity and ameliorates the biochemical damages in maize.
RESUMO: O objetivo do estudo foi avaliar a resposta bioquímica do milho, sob stresse salino, inoculado com Bacillus subtilis. Quatro níveis de salinidade foram avaliados: 0mM, 50mM, 100mM e 200mM de cloreto de sódio (NaCl). Condições salinas influenciaram negativamente o crescimento do milho. Entretanto, a inoculação com B. subtilis melhorou o crescimento das plantas no maior nível de NaCl. O teor de clorofila decresceu enquanto que a prolina aumentou em plantas submetidas aos níveis salinos e inoculadas com B. subtilis. B. subtilis também aumentou o conteúdo de agua foliar. A inoculação com B. subtilis promove melhor crescimento das plantas sob salinidade e atenua os danos bioquímicos no milho.
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ABSTRACT Forty isolates of endophytic bacteria isolated from banana tree roots were assessed as to their capacity to solubilize phosphate in a solid culture medium supplemented with different inorganic and one organic source of phosphorus. The amount of phosphorus (P) in each liquid medium was quantified, and an indirect assessment of acid phosphatase activity was performed. All assays had a fully randomized design, with three repetitions. Approximately 67.5% of the 40 isolates assessed in solid medium solubilized phosphorus from tricalcium phosphate and 7.5% of the isolates solubilized phosphorus from soy lecithin; no isolates exhibited P solubilization capacity in medium supplemented with iron phosphate. Acid phosphatase activity was detected in 65% of the isolates; Aneurinibacillus sp. and Lysinibacillus sp. isolates presented with the best solubilization indexes. All of the assessed isolates exhibited a capacity to reduce the potential of hydrogen in liquid medium supplemented with tricalcium phosphate. Isolate EB. 78 (Bacillus sp.) exhibited P solubilization capacity in solid media when Ca3(PO4)2 and soy lecithin were used as P sources; this isolate significantly reduced the pH of the liquid medium and exhibited acid phosphatase activity. The results of the present study highlight isolates that exhibit variations in their capacity to solubilize P. These isolates should be used in future tests to assess their field performance.
Subject(s)
Phosphates/metabolism , Bacteria/metabolism , Biodegradation, Environmental , Musa/microbiology , Endophytes/physiology , Bacteria/classificationABSTRACT
The aim of this research was to evaluate whether the application of two plant growth-promoting (rhizo)bacteria might reduce nitrogen fertilization doses in cotton. We used strains Azotobacter chroococcum AC1 and AC10 for their proven ability to promote seed germination and cotton growth. These microorganisms were characterized by their plant growth-promoting activities. Then, we conducted a glasshouse study to evaluate the plant growth promoting ability of these strains with reduced doses of urea fertilization in cotton. Results revealed that both strains are capable of fixing nitrogen, solubilizing phosphorus, synthesizing indole compounds and producing hydrolytic enzymes. After 12 weeks, the glasshouse experiment showed that cotton growth was positively influenced due to bacterial inoculation with respect to chemical fertilization. Notably, we observed that microbial inoculation further influenced plant biomass (p<0.05) than nitrogen content. Co-inoculation, interestingly, exhibited a greater beneficial effect on plant growth parameters compared to single inoculation. Moreover, similar results without significant statistical differences were observed among bacterial co-inoculation plus 50% urea and 100% fertilization. These findings suggest that coinoculation of A. chroococcum strains allow to reduce nitrogen fertilization doses up to 50% on cotton growth. Our results showed that inoculation with AC1 and AC10 represents a viable alternative to improve cotton growth while decreasing the N fertilizer dose and allows to alleviate the environmental deterioration related to N pollution.
El objetivo de esta investigación fue evaluar si la aplicación de 2 (rizo)bacterias promotoras del crecimiento vegetal podría reducir la dosis de fertilizante nitrogenado en el cultivo de algodón. Se usaron las cepas Azotobacter chroococcum AC1 y AC10 por su habilidad para promover la germinación de semillas y el crecimiento del algodonero. Estos microorganismos fueron caracterizados sobre la base de sus actividades de promoción del crecimiento vegetal. Luego se realizó un estudio de invernadero con plantas de algodón para evaluar la capacidad de promoción del crecimiento vegetal de dichas cepas con dosis reducidas de urea. Los resultados revelaron que ambas cepas son capaces de fijar nitrógeno, solubilizar fósforo, sintetizar compuestos indólicos y producir enzimas hidrolíticas. Después de 12 semanas, el experimento de invernadero permitió observar que el crecimiento del algodón fue influido positivamente por la inoculación bacteriana con respecto a la fertilización química. En particular, se evidenció que la inoculación microbiana impactó más en la biomasa vegetal (p<0,05) que en el contenido de nitrógeno. Curiosamente, la coinoculación exhibió un mayor efecto positivo sobre los parámetros de crecimiento en comparación con la inoculación simple. Además, se observaron resultados similares, sin diferencias estadísticamente significativas, entre la coinoculación bacteriana más del 50% de urea y el 100% de fertilización. Estos hallazgos indican que la coinoculación de las cepas de A. chroococcum AC1 y AC10 permitiría reducir las dosis de fertilización nitrogenada del cultivo de arroz en hasta el 50% y aliviar, de esta manera, el deterioro ambiental relacionado con la contaminación por N.
Subject(s)
Azotobacter , Gossypium , Fertilizers , Bacteria , Gossypium/growth & development , NitrogenABSTRACT
ABSTRACT The capacity to solubilize phosphate and to produce indole compounds Indole Acetic Acid type, was evaluated in 15 strains isolated from castor bean lignocellulosic residues (Ricinus communis). To determine the solubilizing activity of phosphates a qualitative test by using Pikovskaya culture medium was employed and for the evaluation of the production of indole compounds (IAA) a Salkowsky colorimetric analysis technique was applied. Among the microorganisms tested, the Bacillus pumilus GIBI 206 demonstrated capacity to solubilize phosphates and Bacillus subtilis GIBI 200 showed of capacity to solubilize phosphates and to produce Indoleacetic Acid (IAA). To determine the effect of the Bacillus subtilis strain on germination and growth promotion, tomato seeds (Solanum lycopersicum 'Santa Clara') were inoculated; the inoculation of the seeds along with the microorganism revealed statistically significant differences, during the germination stage compared to the control treatment. Nevertheless, it revealed a positive influence on the development of tomato plants, originating a significant increase on the mass and length of its stem and root. The results of this research offer the possibility of using the Bacillus subtilis as a growth promoter in tomato seedlings and in the formulation of bio-products.
RESUMEN La capacidad para solubilizar fosfatos y producir compuestos indólicos del tipo Ácido Indol Acético, se evaluó en 15 cepas aisladas de residuos lignocelulósicos de higuerilla (Ricinus communis). Para determinar la actividad solubilizadora de fosfatos se realizó una prueba cualitativa utilizando medio de cultivo Pikovskaya y para evaluar la producción de compuestos indólicos (AIA) se empleó la técnica colorimétrica de Salkowsky. Entre los microorganismos evaluados, Bacillus pumilus GIBI 206 mostró tener la capacidad para solubilizar fosfatos y Bacillus subtilis GIBI 200 evidenció capacidad para solubilizar fosfatos y producir Ácido Indolacético (AIA). Para determinar el efecto de la cepa Bacillus subtilis sobre la germinación y promoción de crecimiento, se inoculó en semillas de tomate (Solanum lycopersicum cultivar Santa Clara); la inoculación de las semillas con el microorganismo no mostró diferencias estadísticamente significativas en el tiempo de germinación en comparación con el tratamiento control, sin embargo mostró influir positivamente en el desarrollo de las plantas de tomate generando un aumento significativo sobre la masa y longitud del tallo y de la raíz. Los resultados de esta investigación ofrecen la posibilidad de utilizar a Bacillus subtilis como promotora de crecimiento en plántulas de tomate y en la formulación de bioinsumos.
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Plant growth-promoting bacteria (PGPB) comprise of soil microorganisms that cause positive effects on plant growth. The hypothesis according to which the inoculation of lima bean with PGPB Bacillus stimulates vegetative growth, which may result in a higher plant productivity, was tested. Thus, this study aimed to evaluate the effects of inoculation of two varieties of lima bean (branca and boca de moça) with Bacillus sp., UFPEDA 472 strain, based on plant growth responses. The experiment was conducted in a greenhouse using a completely randomized design. Three treatments were applied separately to each lima bean variety: the first used inoculation with Bacillus, one was submitted to nitrogen supplementation, and one was the absolute control (non-inoculated plants). The following variables were evaluated: absolute and relative growth rate, root length, stem diameter, fresh and dry mass of shoots and roots, shoot:root ratio and total chlorophyll. The results showed that lima bean displayed better growth responses when inoculated with Bacillus sp. UFPEDA 472 in relation to the treatment with nitrogen and/or non-inoculated plants. When inoculated with PGPB Bacillus, the lima bean var. branca was superior to boca de moça in terms of root length and root dry mass. The lima bean var. boca de moça inoculated with Bacillus sp. UFPEDA 472 was superior to branca in terms of absolute growth rate, stem diameter, fresh and dry mass of shoot, shoot:root ratio and total chlorophyll. In general, the lima bean var. boca de moça inoculated with Bacillus shows a better growth performance. Our results suggest that growth responses of lima bean varieties branca and boca de moça are related with a positive interaction with the PGPB Bacillus.
Bactérias promotoras de crescimento em plantas (BPCP) compreendem microrganismos do solo que causam efeitos positivos no crescimento vegetal. A hipótese de que a inoculação de feijão-fava com BPCP Bacillus estimula o crescimento vegetativo, o qual pode resultar em uma maior produtividade vegetal, foi testado. Assim, este estudo objetivou avaliar o efeito da inoculação de duas variedades de feijão-fava (branca e boca de moça) com Bacillus sp., estirpe UFPEDA 472, baseado em respostas de crescimento vegetal. O experimento foi conduzido em casa de vegetação usando um delineamento completamente ao acaso. Três tratamentos foram aplicados separadamente à cada variedade de feijão-fava: o primeiro utilizou a inoculação com Bacillus sp. UFPEDA 472, um foi submetido à suplementação com nitrogênio e um foi o controle absoluto (plantas não inoculadas). As seguintes variáveis foram avaliadas: taxa de crescimento absoluto e relativo, comprimento das raízes, diâmetro do caule, massa fresca e seca da parte aérea e raízes, relação parte aérea:raiz e clorofila total. Os resultados mostram que o feijão-fava exibiu melhores respostas de crescimento quando inoculadas com Bacillus sp. UFPEDA 472 em relação ao tratamento com nitrogênio e/ou às plantas não inoculadas. Quando inoculado com Bacillus sp. UFPEDA 472, o feijão-fava var. branca foi superior à boca de moça em termos de comprimento e massa seca das raízes. O feijão-fava var. boca de moça inoculado com Bacillus sp. UFPEDA 472 foi superior à branca na taxa de crescimento absoluto, diâmetro do caule, massa fresca e seca da parte aérea, relação
Subject(s)
Bacillus , Bacteria , Phaseolus/growth & developmentABSTRACT
The plant growth promoting psychrotrophic Bacilli were investigated from different sites in north western Indian Himalayas. A total of 247 morphotypes were obtained from different soil and water samples and were grouped into 43 clusters based on 16S rDNA-RFLP analysis with three restriction endonucleases. Sequencing of representative isolates has revealed that these 43 Bacilli belonged to different species of 11 genera viz., Desemzia, Exiguobacterium, Jeotgalicoccus, Lysinibacillus, Paenibacillus, Planococcus, Pontibacillus, Sinobaca, Sporosarcina, Staphylococcus and Virgibacillus. With an aim to develop microbial inoculants that can perform efficiently at low temperatures, all representative isolates were screened for different plant growth promoting traits at low temperatures (5-15°C). Among the strains, variations were observed for production (%) of indole-3-acetic acid (20), ammonia (19), siderophores (11), gibberellic acid (4) and hydrogen cyanide (2); solubilisation (%) of zinc (14), phosphate (13) and potassium (7); 1-aminocyclopropane-1-carboxylate deaminase activity (6%) and biocontrol activity (4%) against Rhizoctonia solani and Macrophomina phaseolina. Among all the strains, Bacillus licheniformis, Bacillus muralis, Desemzia incerta, Paenibacillus tylopili and Sporosarcina globispora were found to be potent candidates to be developed as inoculants as they exhibited multiple PGP traits at low temperature.
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La productividad y sostenibilidad de la agricultura en Colombia pueden ser influidas positivamente a través del aprovechamiento de la biodiversidad para la producción de bioinsumos. Fueron analizados a mediano y largo plazo, los posibles escenarios futuros generados por las regulaciones que intervienen en el avance tecnológico de los bioinsumos, a través de la aplicación de una encuesta Delphi, con la participación de 23 expertos, teniendo en cuenta las tres dimensiones del desarrollo sostenible. Sobre la base de este estudio, se encontró que el 65% de los expertos consideran que el impacto de la innovación o el desarrollo tecnológico del uso de bioinsumos en la producción agrícola, tiene un alto impacto económico con un nivel de concordancia significativo (≥0.05). Adicionalmente, el 65% seleccionó como el mejor escenario, en el cual se den condiciones que promuevan mayor desarrollo, acceso y aplicación de los bioinsumos, de tal forma que se incremente el ritmo de incorporación de la tecnología por parte de los productores. En conclusión, más allá del nivel de desarrollo tecnológico, es necesario revisar los procesos legislativos para la comercialización de los bioinsumos, fue evidente que el éxito futuro de la industria de la producción de productos biológicos dependerá de la gestión de empresas innovadoras, la eficiente comercialización de los mismos, la educación y transferencia a los productores y el progreso de la investigación.
Productivity and sustainability of agriculture in Colombia can be influenced positively through the use of biodiversity for the production of bioinoculants. They were analyzed in the medium and long term, the future scenarios generated by the regulations involved in the technological advancement of bio-products through the application of a Delphi survey, with the participation of 23 experts in bio-products, taking into account the three dimensions sustainable development. Based on this study, it was found that 65% of the experts believe that the impact of innovation and technological development of the use of bio- products in agricultural production, has a high economic impact with a significant level of agreement (≥0.05). Additionally, 65% selected as the best scenario, in which conditions that promote greater development, access and application of bio-products, so that the rate of adoption of technology is increased by the producers to make. In conclusion, beyond the level of technological development is necessary to revise the legislative process for the marketing of bio-products, it was clear that the future success of the industry in the production of biological products depend on the management of innovative enterprises, efficient marketing thereof, education and transfer to producers and the progress of the investigation.
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En Cuba, entre los esfuerzos por lograr la sostenibilidad en la agricultura se han empleado biopreparados a gran escala, los cuales han tenido un gran impacto económico, ecológico y social. La caña de azúcar constituye uno de los principales cultivos agrícolas para nuestro país y tiene gran importancia desde los puntos de vista económico y ecológico a nivel mundial. En el presente trabajo se demostró el efecto de diferentes fuentes de carbono y nitrógeno en el crecimiento de 5 cepas endófitas de caña de azúcar, 3 de Gluconacetobacter diazotrophicus, una de Bacillus licheniformis y una de Enterobacter agglomerans. De igual forma, se estudió la influencia de jugos provenientes de cinco variedades, así como diferentes concentraciones de las fitohormonas ácido 3 indolacético (AIA) y ácido giberélico (GA) en el crecimiento. Se demostró que la asparagina y el sulfato de amonio como fuentes de nitrógeno adicionadas al medio LGI posibilitan un mayor crecimiento de las bacterias endófitas estudiadas. El medio LGI suplementado con jugo de caña de azúcar favorece significativamente (p≤0,05) el crecimiento de los microorganismos endófitos y no existe relación directa entre el origen varietal del jugo y de las cepas. Por otra parte las fitohormonas en bajas concentraciones favorecieron el crecimiento, no ocurriendo así cuando se encuentran a elevadas concentraciones en el medio de cultivo. Es necesario estudiar todos los factores que pueden influir en la interacción entre la planta y los endófitos para poder utilizar sus potencialidades como promotores del crecimiento vegetal.
Among the efforts done in Cuba to the sustainability in the agricultural system, one of them is the use of bioproducts, which have a relevant economic, ecological and social impact. The sugarcane is one of main crops in our country and it has a great importance at world level. In the present work is demonstrated the effect of different carbon and nitrogen sources in the growth of 5 entophytic bacteria (three of Gluconacetobacter diazotrophicus, one of Bacillus licheniformis and one of Enterobacter agglomerans) were demonstrated. As the same form are studied the influence of juices from five varieties, as well as, different concentrations of fitohormones indole3acetic acid and giberelic acid on the growth. Was demonstrated that asparagine and ammonium sulfate as nitrogen sources added to LGI medium enhance the growth a major growth of the studied endophytic bacteria. The LGI medium supplied with juices of sugarcane enhance the growth of microorganisms (p≤0,05) and don't exist any relationships among the origin of the juice and the strains. On the other hand, the fitohormones at low concentrations don't affect the growth but at high levels of these hormones inhibit the growth. It's necessary to study the factors that have influence on the interaction between the plant and endophytes to use their potentialities as plant growth promoters.
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Microorganisms that live inside and around a plant can supply it with essential substances, such as phytohormones and essential nutrients. The present investigation aimed to isolate and characterize the phyllosphere, the endophytic, and the water tank bacteria associated with Vriesea gigantea and Tillandsia aeranthos. The bacteria were tested for siderophore and indole-3-acetic acid (IAA) production, phosphate solubilization, and presence of the nif H gene. Genetic diversity of the bacterial isolates was evaluated by rep-PCR. Sixty-eight bacterial strains were isolated from 3 different microhabitats of V. gigantea and from 2 microhabitats of T. aeranthos bromeliad plants. Gram-positive, spore-forming bacilli comprised most bacterial isolates. All isolates produced IAA in vitro in presence of very low amounts of tryptophan. More than 70% of the evaluated bacteria presented the ability of siderophore production and phosphate solubilization, and possessed the nif H gene. It was not possible to distinguish well-defined groups of isolates based on the bromeliad species and microhabitat they inhabit using genetic characterization by rep-PCR. Water tanks presented the most abundant diversity compared with phyllosphere and endophytes, probably due to the high nutrient concentration, which promotes an ideal environment for complex microbial communities.
Microrganismos que habitam o interior e a superfície podem fornecer substancias essenciais ao crescimento das plantas, como fitormônios e nutrientes essenciais. O presente trabalho teve como objetivo isolar e caracterizar as bactérias da filosfera, do ambiente endofítico e a água de tanque associadas à Vriesea gigantea e Tillandsia aeranthos. As bactérias foram submetidas a testes de verificação de produção de sideróforos e de ácido indol acético (AIA), solubilização de fosfatos, e a presença do gene nif H. A diversidade genética dos isolados bacterianos foi analisada por rep-PCR. Sessenta e oito microrganismos foram isolados de 3 microambientes distintos de V. gigantea e de 2 microambientes de T. aeranthos. A maioria das bactérias isoladas foram bacilos formadores de esporos, gram-positivos. Todos os isolados produziram AIA in vitro na presença de quantidades pequenas de triptofano. Mais de 70% das bactérias analisadas produziram sideróforos, solubilizaram fosfatos e possuíam o gene nif H. Não foi possível distinguir grupos definidos de microrganismos baseados no microhabitat e na espécie de bromélia de onde foram isolados usando rep-PCR. A água do tanque apresentou maior diversidade microbiana quando comparada com a filosfera e o ambiente endofítico, provavelmente devido à alta concentração de nutrientes, que promove um ambiente favorável para o desenvolvimento de comunidades microbianas complexas.
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Se obtuvieron antisueros en conejo utilizando como antígeno el AIA adherido a membranas de nitrocelulosa que mostraron un elevado título y especificidad. Mediante la técnica de inmunoadsorción por manchas marcadas con oro coloidal se detectó la producción de esta auxina por cepas de los géneros Gluconacetobacter, Herbaspirillum, Azospirillum, Pseudomonas, Burkholderia y Bacillus empleando como antígenos los sobrenadantes de los cultivos. Para cuantificar la producción de AIA y corroborar los datos obtenidos se empleó la técnica colorimétrica derivada de Salkowski. Los resultados muestran que todos los géneros bacterianos estudiados tienen la capacidad de producir AIA y se demuestra la factibilidad del uso de este antisuero policlonal para la detección de este metabolito. Teniendo en cuenta las potencialidades de estas bacterias, resulta de gran importancia la utilización de antisueros y técnicas serológicas para la detección rápida y sencilla de este tipo de metabolitos en bacterias asociadas a cultivos de interés económico.
Rabbit polyclonal antisera against indoleacetic acid (IAA) bound to nitrocellulose membrane were obtained, which exhibited a high titer and specificity. The dot immunobinding technique with colloidal gold was used to detect auxin production by several strains belonging to Gluconacetobacter, Herbaspirillum, Azospirillum, Pseudomonas, Burkholderia and Bacillus genera, using culture supernatants as antigens. Moreover, auxin production was quantified by the Salkowski's method to corroborate the previous results. It was found that that all the studied microorganisms produce IAA and the feasibility of using these antisera to detect the metabolite was confirmed. Taking into account the potentialities of plant growth promoting bacteria as biofertilizers, the use of these antisera for a rapid and easy detection of IAA in bacteria associated with important crops is thus recommended.
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Se conoce que el quorum sensing es un atributo común de muchas especies bacterianas y que puede ser un carácter universal de las bacterias. Actualmente se están describiendo a un paso más rápido nuevas señales y nuevos sistemas de regulación por quorum sensing y se han desarrollado las investigaciones acerca de la comunicación célula-célula en bacterias basada en el mecanismo de quorum sensing. En los ambientes naturales existen muchas bacterias que viven juntas y utilizan varias clases de moléculas señales. Dentro de las señales especie específicas predominan las acilhomoserín lactonas (AHLs), pero ya se han descrito una amplia diversidad de moléculas involucradas en la señalización célula-célula. Numerosos bioensayos y sistemas sensores se han desarrollado para la detección, caracterización y cuantificación de las AHLs. Se han obtenido evidencias de la acción de estas moléculas señales en la colonización de la rizosfera, el swarming, las interacciones simbióticas y la capacidad de interrumpir el proceso de señalización de otras bacterias que convivan en el mismo ambiente. Todas estas potencialidades de las bacterias que involucran el mecanismo de quorum sensing, pudieran ser utilizadas para fortalecerla acción estimuladora del crecimiento vegetal y el control biológico de patógenos en los agroecosistemas sostenibles.
The quorum sensing is a common attribute in some bacterial species. Currently, several signals and new regulation systems are describing and the researchers are very interested in the cell-cell communication based on quorum sensing mechanism. In the natural environments several bacteria are living together, then several types of signal molecules are using. The acylhomoserines lactones (AHLs), are predominant, but a wide range of molecules are involved in cell-cell communication. To detect, characterization and quantification of signals numerous bioassays and sensors systems were developed. It were demonstrated the action of signals molecules in the rhizosphere colonization, swarming, symbiotic interactions and the capacity to break the signaling process of another microorganism in the same environment. These potentialities of bacteria would be used to improve the plant growth stimulation and biological control of pathogens in sustainable agricultural.
Subject(s)
Quorum Sensing/radiation effects , Quorum Sensing/immunology , Bacteria, Anaerobic/chemistryABSTRACT
The use of microorganisms to improve the availability of nutrients to plants is of great importance to agriculture. This study aimed to evaluate the effect of triple inoculation of cowpea with arbuscular mycorrhizal fungi (AMF), plant growth-promoting bacteria (PGPB) and rhizobia to maximize biological nitrogen fixation (BNF) and promote plant growth. The experiment was conducted in a greenhouse using cowpea plants (Vigna unguiculata L. Walp cv. IPA 206). The treatments included inoculation with strains of Bradyrhizobium sp. (BR 3267 and EI - 6) individually and as a mixture, an absolute control (AC) and mineral nitrogen control (NC), all combined with the presence or absence of native AMF (Glomus etunicatum) and PGPB (Paenibacillus brasilensis - 24) in a 5x2x2 factorial design. All treatments were replicated three times. Contrasts were performed to study the treatment of variables. Inoculation with Bradyrhizobium sp. (BR 3267 and EI - 6) and G. etunicatum favored nitrogen acquisition and phosphorus availability for the cowpea plants. Inoculation with P. brasilensis - 24 increased colonization by Bradyrhizobium sp. and G. etunicatum and promoted cowpea growth, while the nitrogen from symbiosis was sufficient to supply the plants nutritional needs.