Strains Of Diazotrophic Bacteria Research Articles

Genetic diversity and inoculation of plant-growth promoting diazotrophic bacteria for production of Eucalyptus urophylla seedlings

The study of diversity and the established relationship between plants and endophytic bacteria contribute significantly to the plant development. This study aimed to isolate, identify plant-growth promoting diazotrophic bacteria from Eucalyptus urophylla plants and evaluate the plant seedling response to inoculation with selected strains. The study was conducted from July 2017 to August 2018 set up in a greenhouse in a completely randomized experimental design with 17 treatments and 16 replicates, with 12 strains isolated from E. urophylla, four standard bacteria and one control (not inoculated with bacteria). Twelve strains were isolated from the eucalyptus rhizosphere using the N-free semisolid media and the 16 rRNA sequencing identified species closely related to Nitrospirillum amazonense, Stenotrophomonas maltophilia, Pantoea agglomerans, Herbaspirillum frisingense and Ideonella dechloratans. All strains were able to produce indol compounds and the presence of the nifH gene (nitrogen fixation) was demonstrated by PCR analysis. There was a significant effect of the strain inoculation on the height, diameter, root dry matter, root length, root area surface and volume of the seedling plant. The strains L1E, L4E - Azospirillum amazonense and L7E - Stenotrophomonas maltophilia presented high values variables of height, diameter, root dry matter, root length, root area surface and volume. Many of the bacterial strains were able to promote plant growth either by root morphology changes or biomass accumulation in root and shoots. Therefore, there is a biotechnological potential of these plant-growth promoting diazotrophic bacteria strains to be applied as inoculants to improve growth of eucalyptus seedlings. This fact opens new opportunities to establish forests with economically viable and environmentally sustainable technologies

Nitrogen acquisition and 15N-fertiliser recovery efficiency of sugarcane cultivar RB92579 inoculated with five diazotrophs

We aimed to evaluate N acquisition and 15N-fertiliser recovery efficiency of sugarcane as a function of N fertilisation and inoculation with plant growth-promoting diazotrophic bacteria (PGPDB) during the first crop season. A field experiment was performed with a randomized complete block design consisting of four replications and four treatments: control without N and without inoculation; control without N but with inoculation of a mixture of five strains of diazotrophic bacteria; N treatment (50 kg ha−1 N-urea) without inoculation; and N treatment with inoculation. Over seven harvests, we evaluated crop growth, biomass accumulation, N content, and N recovery using 15N-urea (excess of 1.5% atoms 15N). In addition, the contribution of biological N fixation (BNF) was measured using the 15N natural abundance technique in the plots without N fertiliser application. Inoculation with the mixture of five PGPDB strains increased the yield by 15% and N content in the shoots by 18% over the cycle. The average contribution of N fertiliser in plant N nutrition was 13%; other sources accounted for a large part of N in the shoots. Plants received N via BNF in 31% (average) of the treatments during the plant cycle; however, inoculation did not interfere with this process. The recovery efficiency of 15N-fertiliser was 50% in this first cycle with no differences among inoculation treatments. Nitrogen fertiliser applied to sugarcane resulted in a low impact on N accumulation, and a single application of an inoculant improved plant growth by mechanisms other than BNF.

Associative diazotrophic bacteria inoculated in sugarcane cultivars: implications on morphophysiological attributes and plant nutrition

Sugarcane is one of the first activities of economic importance in Brazil. The understanding of the nutritional dynamics at different phenological stages of the sugarcane crop with the use of nitrogen-fixing bacteria has been one of the alternatives to decrease fertilizer consumption and increasing plant production. This study aimed to assess the morphophysiological attributes in the initial growth and nutrition of two sugarcane varieties inoculated with strains of diazotrophic bacteria, individually and in an association, in a greenhouse. The [...]

Bacterial strains decrease solubility of potassium in the soil

Current study verifies whether inoculation with strains of diazotrophic bacteria, with proven ability to solubilize potassium (K) in vitro, contributes towards the release of K in the soil after fertilization with phonolite rock powder. The experiment was conducted in containers with 0.3 dm-3 of soil containing low potassium content. Fifteen treatments were used, namely, 12 inoculated with the bacterial strains, a control treatment (without phonolite and without inoculation), one containing phonolite without inoculation and one containing KCl, soluble fertilizer, without inoculation. In treatments with phonolite and KCl, the doses of these materials were applied to provide the soil with 195 mg dm-3 of K. A completely randomized design with four replications was used. The soil was incubated during 90 days at room temperature and humidity at about 70% retention capacity. After this period, the content of K+ (Mehlich and resin), pH value and potential acidity (H+Al) were evaluated. Phonolite, associated with inoculation with most bacterial strains, increased the availability of potassium in the soil, pH rate and reduced potential acidity. Among the strains tested, UNIFENAS 100-01, UNIFENAS 100-16, UNIFENAS 100-27, UNIFENAS 100-39 and UNIFENAS 100-93 were the most efficient for the solubilization of K+ of the phonolite. In spite of the observed results, K content released by the bacterial strains in the soil decreased when compared to in vitro conditions, thus justifying the need for studies on bio-solubilization of soil to select the most efficient strains in the process.

Biofertilizing potential of a fertilizer based on cienego and native microorganisms in corn seeds

In the development of the productive process of stone aggregates, during the stage of washing and extraction of sludge from the decanter wells, a “cienego” sand is produced in an approximate quantity of 24.75 tons per day, of which only 10% per day is commercialized, the remaining 90% must be discarded, causing financial detriment, impact on the environment in terms of pollution by handling the product that is discarded, occupation of useful areas and landscape degradation, among other impacts negatively affecting the companies in the sector, and their environment. The objective of this research was to evaluate a fertilizer based on cienego and three native microorganisms (Azotobacter sp, 1 Azotobacter sp, 2 and Pseudomonas sp) in corn seeds. For this purpose, three native strains of diazotrophic bacteria were isolated from soil samples of oil palm crops in Tibú, located at Norte de Santander, Colombia, which were biochemically identified using traditional culture media. These isolates were inoculated into corn seeds in trays with sterile soil plus ciénego at 70/30 ratio respectively, and the plant growth-promoting effect was recorded every 4 days, by measuring morphological variables such as height, number of leaves, number of roots, length and germination rate. The results showed that Azotobacter sp, 2 treatment presented a higher production of roots, reached greater height (cm), number of leaves and germination rate in comparison to control treatment after 12 days of monitoring, besides directly influencing the percentage of organic matter in the substrate and elements such as calcium, potassium and phosphorus, allowing greater productivity and corn seed yield once these were germinated.

MORPHOLOGICAL, PRODUCTIVE, AND CHEMICAL TRAITS OF XARAÉS GRASS: NITROGEN TOPDRESSING VERSUS INOCULATION WITH DIAZOTROPHIC BACTERIA

Abstract: Nitrogen topdressing is essential for forage production, but the high cost of fertilizers stimulates the search for new technologies, such as the use of diazotrophic bacteria, which can fix the atmospheric nitrogen. To evaluate the potential of this technology in providing the amount of nitrogen requested by xaraés grass as topdressing, plants were fertilized at planting with an N rate of 100 kg ha-1, inoculated with strains of diazotrophic bacteria and Azospirillum brasilense, and compared with plants that received 100 kg ha-1 of N at planting and as topdressing during two periods of shoot growth (58 days in the first period and 26 days in the second period) in 20-dm3 pots. The data were subjected to analysis of variance and means compared by the Scott-Knott test at 5% significance. The leaf area of xaraés grass inoculated with strain UN42 was similar to that of plants that received nitrogen topdressing. However, grass biomass production was higher when nitrogen topdressing was applied. Plant inoculation with Azospirillum brasilense and strains UN16, UN17, UN21, UN33, UN49, and UN78 increased crude protein contents of xaraés grass when compared to nitrogen fertilization at planting without inoculation. However, grass inoculation with diazotrophic bacteria does not replace nitrogen topdressing completely.

Growth promotion of Guinea grass by diazotrophic bacteria1

ABSTRACT The Panicum maximum species (cv. Mombaça) is a forage plant well adapted to the different edaphoclimatic conditions found in Brazil; however, it requires high nitrogen fertilizer doses to ensure high yields. The present study aimed to assess the inoculation effect with associative diazotrophic bacteria strains on the yield and bromatological characteristics of the Guinea grass. A randomized block design was used, consisting of 25 treatments, being 23 of them inoculated with diazotrophic bacteria and two without inoculation (one with and the other without mineral nitrogen), with four repetitions. The analyzed variables were stem diameter; leaf width and length; leaf, stem and root dry mass yield; crude protein; acid and neutral detergent fibers. There were no differences among the treatments for root dry mass, stem diameter and acid detergent fiber. For the remaining variables, a positive effect of the inoculation with diazotrophic bacteria was observed, particularly for the following Unifenas strains: 100-06, 100-13, 100-26, 100-30, 10-35, 100-54, 100-69, 100-71 and 100-94. This reveals the potential of these bacterial strains for use at the sustainable production of the Guinea grass with a reduction in the use of nitrogen inputs.

Biochemical studies of amylase, lipase and protease in Callosobruchus maculatus (Coleoptera: Chrysomelidae) populations fed with Vigna unguiculata grain cultivated with diazotrophic bacteria strains.

The objective of this study was to evaluate the enzymatic activity of homogenates of insects fed on grain of cowpea, Vigna unguiculata (L.), cultivars grown with different nitrogen sources. For the experiment we used aliquots of the homogenate of 100 unsexed adult insects, emerged from 10 g of grain obtained from four cowpea cultivars: 'BRS Acauã', 'BRS Carijó', 'BRS Pujante', and 'BRS Tapaihum' grown under different regimes of nitrogen sources: mineral fertilizer, inoculation with strains of diazotrophs (BR 3267, BR 3262, BR 3299; INPA 03-11B, 03-84 UFLA, as well as the control (with soil nitrogen). The parameters evaluated were enzymatic activities of insect protease, amylase and lipase and the starch content of the grains. There were differences in the enzymatic activity of amylase, lipase and protease of insect homogenate according to the food source. A lower activity of the enzyme amylase from C. maculatus homogenate was observed when insects were fed grain of the cultivar BRS Carijó. A lower activity of lipase enzyme from C. maculatus homogenate was observed when the insects fed on grain from the interaction of the cultivar Tapaihum inoculated with BR 3262 diazotrophs. The lowest proteolytic activity was observed in homogenate of insects fed on interaction of 'BRS Carijó' inoculated with BR 3262 diazotrophs. Starch content correlated positively with the amylase activity of C. maculatus homogenate. The cultivar BRS Carijó had a different behavior from the other cultivars, according to the cluster analysis.

Potassium solubilization in phonolite rock by diazotrophic bacteria

Some strains of nitrogen fixing bacteria, besides fixing the N2, can produce phytohormones, control pathogens, act in solubilization of minerals containing phosphorus (P) and potassium (K), contributing to plant growth. However, the solubilization of minerals containing K has been little exploited. Therefore, the aim of this study was to evaluate potassium solubilization (K) of phonolite rock by strains of associative nitrogen fixing bacteria supplied with two different carbon sources. Twelve bacterial strains were cultured for seven days at 25°C in Aleksandrov medium supplemented with phonolite rock powder. The experiment was carried out in a completely randomized factorial design, 13 x 2 (12 bacterial strains and a control without inoculation) and two carbon sources (glucose and sucrose) with four repetitions. After the growth, the supernatant was separated by centrifugation and analyzed for the final pH value and the content of K. All diazotrophic bacteria strains contributed to increase the release of K when compared to the control treatment. The strain UNIFENAS 100-94 solubilized 130 mg L-1 K in the presence of the two carbon sources, indicating the potential use of these diazotrophic bacterial strains for K solubilization from minerals.

Effects of Selected Diazotrophs on Maize Growth.

Laboratory, greenhouse, and field experiments were conducted at the University of KwaZulu-Natal, Pietermaritzburg, South Africa in the 2010/2011 and 2011∖2012 seasons to study the effects of eight strains of diazotrophic bacteria on the growth and yield of maize. Maize seeds were treated with Bacillus megaterium (V16), Pseudomonas sp. (StB5, A3, A6, and A61), Burkholderia ambifaria (V9), Enterobacter cloacae (L1) and Pantoea ananatis (LB5), aiming to stimulate plant growth, and maintain or increase yields while reducing the need for N fertilization. All the diazotrophic bacteria increased germination of maize seed, and Pseudomonas sp. (StB5) and B. megaterium (V16) significantly increased shoot length. Pseudomonas sp. (StB5), B. megaterium (V16), E. cloacae (L1), B. ambifaria (V9), and Pseudomonas sp. (A3) very significantly increased root length and seed vigor index. Under greenhouse conditions, plants treated with diazotrophic bacteria developed more leaf chlorophyll and greater dry weight, albeit not significantly (n.s.). In a field trial in 2010/2011, application of the best five diazotrophic bacteria, with or without 33% N-fertilizer, had no significant effect on germination, grain yield, dry weight, plant height and leaf chlorophyll. In the 2011/2012 growing season, at 60 days after planting (DAP), all the diazotrophic bacteria increased plant dry weights to equal that of the fertilized control (33%N-fertilizer) (n.s.). After inoculation with the diazotrophs alone increased plant heights (n.s.), and chlorophyll contents (n.s.). With the addition of 33%N-fertilizer at planting, the diazotrophs still caused increases of chlorophyll content relative to the control with 33%N (n.s.). It may be concluded that the tested diazotrophs alone may be beneficial for use on maize growth.

The damage caused by Callosobruchus maculatus on cowpea grains is dependent on the plant genotype.

Beans from cowpea cultivars fertilized with mineral N or inoculated with various rhizobium strains may contain different nitrogen concentrations and nitrogen metabolite composition, which affects the beans' defense mechanisms against pests. In this study, the population growth of Callosobruchus maculatus reared on beans from four cowpea cultivars fertilized with different nitrogen sources was evaluated. The factors tested were beans from four cowpea cultivars and seven different nitrogen sources: mineral N fertilization, inoculation with five strains of symbiotic diazotrophic bacteria, and soil nitrogen (absolute control). BRS Tapaihum and BRS Acauã cultivars had lower cumulative emergence and instantaneous rate of population growth of the insects compared with other cultivars, indicating antixenosis resistance against C. maculatus. Inoculation of BRS Acauã cultivar with the diazotrophic bacteria strain BR 3299 resulted in higher mortality of C. maculatus. For BRS Tapaihum cultivar, inoculation with diazotrophic bacteria strains BR3267, BR 3262 and BR 3299, and nitrogen fertilization resulted in higher mortality among C. maculatus. BRS Tapaihum and BRS Acauã cultivars showed the lowest cumulative insect emergence and instantaneous rates of population growth, and the highest insect mortality, mainly when the grains were obtained from plants inoculated with rhizobial strains. © 2016 Society of Chemical Industry.

Desenvolvimento Inicial de Duas Variedades de Cana-de-açúcar Inoculadas com Bactérias Diazotróficas

RESUMO A cana-de-açúcar é uma cultura de grande destaque na economia, em razão da produção de açúcar, etanol e energia. Tecnologias que possam contribuir para o aumento da produtividade e qualidade da cultura com mínimos danos ao meio ambiente são necessárias. Objetivou-se avaliar a produção de ácido indol acético de cinco estirpes de bactérias diazotróficas e o efeito da inoculação delas na brotação de duas variedades de cana-de-açúcar, RB867515 e IACSP95-5000. A produção de auxina foi determinada pelo teste colorimétrico, usando o reagente de Salkowski. Para avaliar a germinação, foi conduzido um experimento em casa de vegetação, utilizando-se delineamento experimental em blocos ao acaso com quatro repetições e sete tratamentos: controle não inoculado; inoculação mista com as cinco estirpes e inoculação individual com Gluconacetobacter diazotrophicus (Gd) estirpe BR11281T(PAL-5T), Herbaspirillum seropedicae (Hs - BR11335 = HRC54), Herbaspirillum rubrisubalbicans (Hr - BR11504 = HCC103), Burkholderia tropica (Bt - BR11366T = PPe 8 T) e Azospirillum amazonense (Aa - BR11145 = CBAMc). As bactérias mais eficientes na produção de auxina foram Hs e Hr, declinando 48 h após o crescimento. Hr, Aa e Bt aumentaram o índice de velocidade de germinação e o número de brotações nas duas variedades. Na var. RB867515, a velocidade de germinação ainda foi positivamente influenciada pela inoculação mista, sendo o mesmo observado pela inoculação de Gd na var. IACSP95-5000.

English

With the aim of isolating and inoculating diazotrophics bacteria, which is an efficient biological nitrogen fixation (BNF) in rice in Vitoria da Conquista - Ba, the present study was carried out in three steps. In the experiment of inoculation of diazotrophics bacteria, BRS Tropical and BRS MG Curinga, inoculation with the strain of bacterium ZAE 94, absence of inoculation and four doses of N (0, 20, 60 and 100 kg ha-1) were used. The control plants were used for the implementation of the isolation of bacteria efficient as the BNF. Final experiment was carried out with the three isolated strain, the ZAE 94, the absence of inoculation and the interaction with doses of N. Inoculation with strains of diazotrophic bacteria, guaranteed an increase in agronomic variables studied with positive effects on production and grain up to 208.5%. Key words: Biological nitrogen fixation (BNF), Herbaspirillum seropedicae, grain production.

Behavior of Callosobruchus maculatus Populations Fed with Vigna unguiculata Grain Cultivated with Diazotrophic Bacteria Strains

Behavior of Callosobruchus maculatus Populations Fed with Vigna unguiculata Grain Cultivated with Diazotrophic Bacteria Strains

Early responses of rice (Oryza sativa L.) seedlings to inoculation with beneficial diazotrophic bacteria are dependent on plant and bacterial genotypes

Rice cultivars, in combination with diazotrophic bacteria, can obtain variable contributions from Biological Nitrogen Fixation (BNF). Plant genetic controls and the genotype of the bacterial strains might regulate in particular ways the plant responses during these associations. Some of this regulation is likely to occur during the first stages of bacterial infection and plant colonization, and some of the early plant responses might involve ethylene signaling, as previously reported for sugarcane. The aim of this work was to investigate whether rice early responses to inoculation with beneficial diazotrophic bacteria and the expression of ethylene receptors (ERs) by the host are dependent on plant and bacterial genotypes. Bacterial colonization, lateral root development and expression of ERs were measured in seedlings of two rice cultivars, IR42 and IAC4440, which, respectively, are known to have higher and lower BNF capabilities. Inoculation experiments were performed with two strains of bacteria: Azospirillum brasilense sp245 and Burkholderia kururiensis M130. Cultivar IR42, which has a relatively high BNF capability, was more colonized by the bacteria early after inoculation in comparison with cv. IAC 4440, which has a lower BNF capability. However, although both cultivars showed a significant increase in lateral root numbers 10 days after inoculation with A. brasilense sp245, plants inoculated with B. kururiensis M130 did not. In addition, a differential ER expression pattern was observed between IR42 and IAC4440 in response to inoculation with the two strains. The expression of ERs was higher in the more BNF-effective cultivar IR42, than in the less BNF-effective cv. IAC4440, especially when cv. IR42 was inoculated with A. brasilense sp245. Moreover, plants associated with B. kururiensis M130 showed a different ER expression profile compared to those inoculated with A. brasilense sp245, with the latter exhibiting greater increases of ER mRNA levels three days after bacterial inoculation. We have shown that two rice genotypes contrasting in their BNF capability responded differentially to early inoculation with different strains of diazotrophic bacteria. The two rice genotypes were colonized with different bacterial numbers during their early association with two strains of diazotrophic bacteria, and the two strains had different effects on the promotion of lateral root development early after inoculation. They also triggered distinct ER expression patterns in the two rice cultivars. These data thus suggest that rice ethylene responses to beneficial diazotrophic bacteria are controlled by both plant and bacterial genotypes.

Survival of endophytic bacteria in polymer-based inoculants and efficiency of their application to sugarcane

Background & aims Studies have been conducted to evaluate maintenance of cell viability and stability, as well as to select cheap carriers to extend the shelf life of plant beneficial bacterial inoculants for agricultural crops. The purpose of this study was to evaluate the shelf life and the colonization efficiency of novel liquid and gel-based inoculant formulations for sugarcane. The different inoculant formulations were all composed of a mixture of five strains of diazotrophic bacteria (Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae, H. rubrisubalbicans, Azospirillum amazonense and Burkholderia tropica), which are recognized as sugarcane growth promoters.

Interação entre fungos micorrízicos arbusculares e bactérias diazotróficas em trigo

O objetivo deste trabalho foi avaliar o efeito da inoculação de dois novos isolados de bactérias diazotróficas endofíticas e da interação destas bactérias com fungos micorrízicos arbusculares (FMAs), na cultura do trigo. Foi realizado um experimento em casa de vegetação, com dois isolados de bactérias diazotróficas endofíticas, IAC11HT (Achromobacter insolitus) e IAC12HT (Zoogloea ramigera), e dois FMAs (Glomus sp. e Acaulospora sp.). Houve efeito sinérgico da co-inoculação na colonização das raízes por bactérias diazotróficas, com o emprego do FMA do gênero Acaulospora. As plantas associadas a Glomus, na presença dos isolados bacterianos, apresentaram maior crescimento, acúmulo e aproveitamento dos nutrientes do que as plantas colonizadas por Acaulospora sp., entretanto, não superaram os tratamentos em que as bactérias e os fungos foram inoculados isoladamente. Apesar de não ter havido efeito benéfico da co-inoculação FMA-bactéria diazotrófica sobre a maioria dos parâmetros avaliados, essas novas bactérias propiciaram o dobro de crescimento, acúmulo e aproveitamento do N e P em plantas de trigo.

Resposta de genótipos de trigo à inoculação de bactérias diazotróficas em condições de campo

O objetivo deste trabalho foi avaliar, em condições de campo, o efeito e a viabilidade econômica da inoculação de novos isolados homólogos de bactérias diazotróficas endofíticas, sob diferentes doses de nitrogênio, em dois genótipos de trigo, em duas localidades. Foram utilizados: três isolados de bactérias diazotróficas endofíticas (IAC-AT-8, Azospirillum brasilense; IAC-HT-11, Achromobacter insolitus; IAC-HT-12, Zoogloea ramigera), dois genótipos de trigo (ITD-19 e IAC-370) e três doses de N, na forma de uréia (0, 60 e 120 kg ha-1). No estádio de quatro folhas e no perfilhamento, foram avaliados a massa de matéria seca e o N acumulado na parte aérea. Na colheita, foram avaliados o teor de N, a massa de 1.000 sementes e a produtividade de grãos. A inoculação promoveu maior massa de matéria seca e N acumulado e aumentou a produtividade de grãos, principalmente na presença de adubo nitrogenado, com lucro para o agricultor. Entretanto, o maior aumento na produtividade de grãos foi obtido nas plantas do genótipo IAC-370, com o emprego do isolado IAC-HT-12, na ausência de N, que superou em 45% o tratamento testemunha. As respostas variaram em relação ao local de cultivo, o que sugere expressiva interação planta-bactéria-ambiente.

Bactérias diazotróficas em mudas de bananeira

Este trabalho objetivou selecionar bactérias diazotróficas isoladas de bananeira (Musa spp.) e avaliar sua influência no crescimento de mudas micropropagadas. Bactérias do tipo Herbaspirillum e relacionadas a Burkholderia cepacia foram inoculadas em plântulas de banana cv. Prata Anã e cv. Caipira. As bananeiras cv. Prata Anã, cultivadas in vitro com substrato pobre em N, apresentaram maior crescimento na presença de bactérias do tipo Herbaspirillum, ao passo que as bananeiras cv. Caipira cresceram melhor com o inóculo contendo bactérias do gênero Burkholderia. Em casa de vegetação, as bananeiras cv. Caipira crescidas em sacolas de plástico contendo areia e vermiculita (1:2), suplementada com a solução de Hoagland contendo 5 mg L-1 de N, apresentaram maior crescimento quando da inoculação simultânea dos dois gêneros de bactérias, em comparação à inoculação individual. A inoculação simultânea proporcionou um crescimento nas bananeiras equivalente ao observado nas plantas-controles adubadas com 50 mg L-1 de N no substrato, porém o teor e o acúmulo de N na parte aérea das bananeiras foram menores. A contribuição de bactérias diazotróficas no crescimento de bananeiras é demonstrada pela primeira vez.