Fe, Mn and 238U Accumulations in Phragmites australis Naturally Growing at the Mill Tailings Pond; Iron Plaque Formation Possibly Related to Root-Endophytic Bacteria Producing Siderophores

Mine drainage is a vital water problem in the mining industry worldwide because of the heavy metal elements and low pH. Rhizofiltration using wetland plants is an appropriate method to remove heavy metals from the water via accumulation in the rhizosphere. Phragmites australis is one of the candidate plants for this method because of metal accumulation, forming iron plaque around the roots. At the study site, which was the mill tailings pond in the Ningyo-toge uranium mine, P. australis has been naturally growing since 1998. The results showed that P. australis accumulated Fe, Mn, and 238U in the nodal roots without/with iron plaque compared with other plant tissues. Among the 837 bacterial colonies isolated from nodal roots, 88.6% showed siderophore production activities. Considering iron plaque formation around P. australis roots, we hypothesized that microbial siderophores might influence iron plaque formation because bacterial siderophores have catechol-like functional groups. The complex of catechol or other phenolics with Fe was precipitated due to the networks between Fe and phenolic derivatives. The experiment using bacterial products of root endophytes, such as Pseudomonas spp. and Rhizobium spp., showed precipitation with Fe ions, and we confirmed that several Pseudomonas spp. and Rhizobium spp. produced unidentified phenolic compounds. In conclusion, root-endophytic bacteria such as Pseudomonas spp. and Rhizobium spp., isolated from metal-accumulating roots of P. australis, might influence iron plaque formation as the metal accumulation site. Iron plaque formation is related to tolerance in P. australis, and Pseudomonas spp. and Rhizobium spp. might indirectly contribute to tolerance. Although there are many issues to be resolved in this research, we hope that the fundamental analysis of plant-microbe interactions would be helpful for phytoremediation at mine sites.

Inoculação do feijoeiro associada à adubação foliar com Cobalto e Molibdênio

Acredita-se que o uso de adubação com cobalto e molibdênio associado à inoculação com Rhizobium spp. na cultura do feijão é capaz de favorecer a produtividade, neste sentido, o objetivo deste trabalho foi avaliar o efeito de doses de inoculante e suas interações com cobalto e molibdênio no cultivo do feijão comum. O experimento foi realizado no campo experimental da Universidade Estadual de Mato Grosso do Sul, em Aquidauana-MS. A cultivar utilizada foi Dama do grupo comercial Carioca. Sendo conduzido em delineamento em blocos casualizados, em esquema fatorial 2x5, com quatro repetições. Constituido da presença ou a ausência da aplicação foliar de cobalto e molibdênio e doses de inoculante (0 mL, 150 mL, 300 mL, 600 mL, 1200 mL a cada 50 kg de sementes). As avaliações realizadas foram matéria verde e seca de nódulos, matéria verde e seca da parte aérea e da raiz, densidade da raiz, número de nódulos por planta, atividade nodular, teor de nitrogênio e fósforo foliar, altura de inserção de primeira vagem, altura de plantas, número de ramificações, número de grãos por vagem, massa de cem grãos e produtividade de grãos. Conclui-se que a associação entre Rhizobium tropici e adubação foliar, com cobalto e molibdênio no feijão comum, embora não tenha promovido aumento de produtividade de grãos resultou em melhoras nos caracteres agronômicos na cultura.

A Complete Analysis of Physiochemical Properties, Microbial Diversity of Soil Along with Economically Important Plant Found in a Tropical Dry Deciduous Forest Debdarha, Bargarh, Odisha

Devdarha is a tropical dry deciduous forest situated in Padampur subdivision of Bargarh district Odisha India. It is present near to Odisha Chhattisgarh border having Latitude 21.12035˚N and longitude 83.04503˚E. The forest is bisected by the Ong River. In this investigation there was an attempt had been made to analyze the physicochemical property of soil, Bacterial diversity of forest soil and Dominant economically important plant species found in Devdarha. In this investigation, it was found that soil was slightly acidic soil having a pH 6.8. High water holding capacity, moisture content, organic carbon content, NPK content indicate that it was fertile soil and luxuriant for plant growth. There were four different species of bacteria found among them Rhizobium spp. important for nitrogen fixation. Here we had found 32 economically important plant species belonging to 17 families. This type of investigation gives us an idea about the interaction of biotic and abiotic components of a typical forest ecosystem.

Selection of Rhizobium spp. Isolates for Inoculation of Field Pea (Pisum sativum)

Rhizobium isolates from wild pea nodules were characterized on the basis of microbiological characteristics. P4, P7, P12, P14, P16, P19, P20, P22, P23 and P24 isolates grew at the 4.5 pH, P5, P6, P11, P12, P13, P14, P16, P17, P19, P20 and P21 isolates grew at 4% NaCl and P7, P8, P10, P11, P12, P14, P19, P20, P22, P23, P24 and P25 isolates grew at 40°C. Resistance to antibiotics (μg mL-1) was investigated in a large propotion of isolates; streptomycin sulphate (80), rifampisin (40), erythromycin (30), chloramphenicol (100), Penicillin (40). In this study, local Rhizobium bacterial isolates were isolated from wild pea root nodules and their efficacy was investigated. Isolates significantly increased plant dry matter weight. The highest nitrogen fixation was achieved with P4 inoculation. Glutamine synthetase and leghemoglobin content of the nodules were determined in the inoculated with the highest P4 isolate. © 2021 Friends Science Publishers

Exopolysaccharide Produced from Rhizobium spp. - An Interesting Product for Industry and Environment

: Most legume species, such as soybeans, beans, and clover, have the ability to establish a symbiotic relationship with nitrogen-fixing bacteria in the soil, which promotes plant growth and productivity. Exopolysaccharide macromolecules are particularly necessary for binding the bacteria to root hairs and initiating the deformation of root hairs, thus trapping the bacteria to initiate root invasion through a tube-like infection thread. Very few studies have focused on the isolation and characterization of new rhizobial exopolysaccharides, despite their unique and specific biological and physicochemical properties. However, rhizobial exopolysaccharides may be studied in detail in the near future, for the development of suitable substitutes for xanthan gum. This review discusses some analytical strategies for characterization of rhizobial exopolysaccharide, the relation between their structure and properties, and a novel application of rhizobial exopolysaccharides. The potential application of exopolysaccharides and living cells as biosorbents has also been reviewed.

Eficiencia en fijación biológica de nitrógeno de cepas de Rhizobium spp. recolectadas en frijol cultivado y silvestre

Se evaluó la eficiencia en fijación biológica de nitrógeno (FBN) de 27 cepas de Rhizobium spp. recolectadas en frijol silvestre y cultivado del occidente de México, al utilizar como hospedero la variedad de frijol Cuarenteño. El trabajo se realizó bajo malla sombra, se usó un diseño experimental completamente al azar con cinco repeticiones y se evaluaron longitud de vástago (LV) y de raíz (LR), peso seco de vástago (PSV) y de raíz (PSR), número de nódulos (NN) y peso seco de nódulos (PSN), nitrógeno total del vástago (NT) y contenido de clorofila (CL). Se realizaron análisis de varianza y de componentes principales; se obtuvieron índices de eficiencia por variable y por grupos de variables. Se detectaron diferencias altamente significativas (P ≤ 0.01) en seis de las ocho variables registradas. Por el valor per se de las variables, se seleccionaron Rhizojal VC3 colectada en frijol silvestre y Rhizojal ZCB3, Rhizojal ZCB1, Rhizojal TP2 y Rhizojal TP3 obtenidas en frijol cultivado. Por índices de eficiencia simples y por grupos de variables, se escogieron Rhizojal VC3, Rhizojal ZCB3 y Rhizojal TP2. El análisis de componentes principales separó a la mayoría de las cepas en dos grupos: cepas procedentes de la forma silvestre de frijol y cepas colectadas en frijol cultivado. Las cepas Rhizojal ZCB3, Rhizojal TP2 y Rhizojal TP3, mostraron los mayores valores en la escala del CP1; la cepa Rhizojal VC3, se ubicó del lado de los aislados de origen cultivado. Considerando los análisis realizados, las cepas identificadas como mejores en FBN fueron Rhizojal VC3 de frijol silvestre y Rhizojal ZCB3 y Rhizojal TP2 de origen cultivado. Los resultados indican que los índices de eficiencia contribuyen a la evaluación y selección de cepas por FBN y que existe potencial para identificar cepas de Rhizobium eficientes en FBN en la región occidente de México.

The Significance of Flavonoids in the Process of Biological Nitrogen Fixation

Nitrogen is essential for the growth of plants. The ability of some plant species to obtain all or part of their requirement for nitrogen by interacting with microbial symbionts has conferred a major competitive advantage over those plants unable to do so. The function of certain flavonoids (a group of secondary metabolites produced by the plant phenylpropanoid pathway) within the process of biological nitrogen fixation carried out by Rhizobium spp. has been thoroughly researched. However, their significance to biological nitrogen fixation carried out during the actinorhizal and arbuscular mycorrhiza–Rhizobium–legume interaction remains unclear. This review catalogs and contextualizes the role of flavonoids in the three major types of root endosymbiosis responsible for biological nitrogen fixation. The importance of gaining an understanding of the molecular basis of endosymbiosis signaling, as well as the potential of and challenges facing modifying flavonoids either quantitatively and/or qualitatively are discussed, along with proposed strategies for both optimizing the process of nodulation and widening the plant species base, which can support nodulation.

Pengaruh Inokulasi Rhizobium spp terhadap Pertumbuhan dan Hasil Produksi Kacang Tanah pada Cekaman Kekeringan

Bondowoso merupakan salah satu kota di Jawa Timur, memiliki kawasan budidaya tadah hujan, sawah dan hutan.Sektor pertanian merupakan sektor unggulan.Kacang tanah merupakan salah satu tanaman yang dibudidayakan.produksi kacang tanah di Bondowoso mengalami penurunan. Penurunan produksi kacang tanah salah satunya dapat disebabkan oleh kekurangan air untuk proses pertumbuhan tanaman sehingga berpengaruh terhadap produksi kacang tanah. Teknologi yang bisa digunakan salah satunya adalah rekayasa irigasi pada lahan tadah hujan, selain rekayasa irigasi perlu adanya rekayasa pemupukan dengan menggunakan Rhizobium spp. Aplikasi inokulumRhizobium spp dengan perlakuan dengan waktu penyiraman 2 hari sekali (P1), 4 hari sekali (P2), 6 hari sekali (P3) dan 8 hari sekali (P4). Hasil percobaan aplikasi Rhizobium spp pada tanaman kacang tanah dengan cekaman kekeringan memberikan efek terhadap pertumbuhan dan produksi kacang tanah. Pengaruh aplikasi Rhizobium spp meningkatkan tinggi tanaman, berat polong basah, berat polong kering, berat biji kering, berat bintil akar.Rhizobium spp dapat memfiksasi nitrogen bebas di udara pada kondisi cekaman kekeringan.Rhizobium dapat menyediakan hara bagi tanaman dalam bentuk NO3-, tumbuhan menggunakan NO3-untuk fotosintesis dan hasil produk berupa protein.Perlakuan terbaik yaitu penyiraman 2 hari sekali dan penambahan Rhizobium spp dengan konsentrasi 20 ml/l.