Publications by authors named "Soumitra P Chowdhury"

Microbiome-based solutions are regarded key for sustainable agroecosystems. However, it is unclear how agricultural practices affect the rhizosphere microbiome, plant-microorganism interactions and crop performance under field conditions. Therefore, we installed root observation windows in a winter wheat field cultivated either under long-term mouldboard plough (MP) or cultivator tillage (CT).

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The beneficial effect of microbial consortium application on plants is strongly affected by soil conditions, which are influenced by farming practices. The establishment of microbial inoculants in the rhizosphere is a prerequisite for successful plant-microorganism interactions. This study investigated whether a consortium of beneficial microorganisms establishes in the rhizosphere of a winter crop during the vegetation period, including the winter growing season.

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The long-term effects of agricultural management such as different fertilization strategies on soil microbiota and soil suppressiveness against plant pathogens are crucial. Therefore, the suppressiveness of soils differing in fertilization history was assessed using two isolates and their respective host plants (lettuce, sugar beet) in pot experiments. Further, the effects of fertilization history and the pathogen AG1-IB on the bulk soil, root-associated soil and rhizosphere microbiota of lettuce were analyzed based on amplicon sequencing of the 16S rRNA gene and ITS2 region.

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sp. SCA7, characterized in this study, was isolated from roots of the bread wheat . Sequencing and annotation of the complete SCA7 genome revealed that it represents a potential new sp.

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Stress tolerant, plant-associated bacteria can play an important role in maintaining a functional plant microbiome and protecting plants against various (a)biotic stresses. Members of the stress tolerant genus are frequently found in the plant microbiome. RL1 was isolated from and the complete genome was sequenced, annotated and analyzed using different bioinformatic tools.

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A better understanding of factors shaping the rhizosphere microbiota is important for sustainable crop production. We hypothesized that the effect of agricultural management on the soil microbiota is reflected in the assemblage of the rhizosphere microbiota with implications for plant performance. We designed a growth chamber experiment growing the model plant lettuce under controlled conditions in soils of a long-term field experiment with contrasting histories of tillage (mouldboard plough vs cultivator tillage), fertilization intensity (intensive standard nitrogen (N) + pesticides/growth regulators vs extensive reduced N without fungicides/growth regulators), and last standing field crop (rapeseed vs winter wheat).

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Fertilization management can affect plant performance and soil microbiota, involving still poorly understood rhizosphere interactions. We hypothesized that fertilization practice exerts specific effects on rhizodeposition with consequences for recruitment of rhizosphere microbiota and plant performance. To address this hypothesis, we conducted a minirhizotron experiment using lettuce as model plant and field soils with contrasting properties from two long-term field experiments (HUB-LTE: loamy sand, DOK-LTE: silty loam) with organic and mineral fertilization history.

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Vegetable crops irrigated with treated wastewater can take up the environmentally persistent pharmaceuticals diclofenac and lamotrigine. This study aimed at quantifying the uptake and translocation of the two pharmaceuticals in lettuce (Lactuca sativa) as well as on the elucidation of the molecular and physiological changes triggered by them. Therefore, plants were cultivated in a phytochamber in hydroponic systems under controlled conditions and treated independently with diclofenac (20 μg L) and lamotrigine (60 μg L) for 48 h.

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Analyses of the spatial localization and the functions of bacteria in host plant habitats through identification by immunological and molecular genetic techniques combined with high resolving microscopic tools and 3D-image analysis contributed substantially to a better understanding of the functional interplay of the microbiota in plants. Among the molecular genetic methods, 16S-rRNA genes were of central importance to reconstruct the phylogeny of newly isolated bacteria and to localize them . However, they usually do not allow resolution for phylogenetic affiliations below genus level.

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In natural environments, plants are exposed to diverse microbiota that they interact with in complex ways. While plant-pathogen interactions have been intensely studied to understand defense mechanisms in plants, many microbes and microbial communities can have substantial beneficial effects on their plant host. Such beneficial effects include improved acquisition of nutrients, accelerated growth, resilience against pathogens, and improved resistance against abiotic stress conditions such as heat, drought, and salinity.

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Bacillus amyloliquefaciens subsp. plantarum FZB42 is a Gram-positive model bacterium for unraveling plant-microbe interactions in Bacilli. In addition, FZB42 is used commercially as biofertilizer and biocontrol agent in agriculture.

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The commercially available inoculant Bacillus amyloliquefaciens FZB42 is able to considerably reduce lettuce bottom rot caused by Rhizoctonia solani. To understand the interaction between FZB42 and R. solani in the rhizosphere of lettuce, we used an axenic system with lettuce bacterized with FZB42 and inoculated with R.

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Application of the plant associated bacterium Bacillus amyloliquefaciens FZB42 on lettuce (Lactuca sativa) confirmed its capability to promote plant growth and health by reducing disease severity (DS) caused by the phytopathogenic fungus Rhizoctonia solani. Therefore this strain is commercially applied as an eco-friendly plant protective agent. It is able to produce cyclic lipopeptides (CLP) and polyketides featuring antifungal and antibacterial properties.

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Bacillus amyloliquefaciens ssp. plantarum FZB42 represents the prototype of Gram-positive plant growth promoting and biocontrol bacteria. In this study, we applied transposon mutagenesis to generate a transposon library, which was screened for genes involved in multicellular behavior and biofilm formation on roots as a prerequisite of plant growth promoting activity.

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The soil-borne pathogen Rhizoctonia solani is responsible for crop losses on a wide range of important crops worldwide. The lack of effective control strategies and the increasing demand for organically grown food has stimulated research on biological control. The aim of the present study was to evaluate the rhizosphere competence of the commercially available inoculant Bacillus amyloliquefaciens FZB42 on lettuce growth and health together with its impact on the indigenous rhizosphere bacterial community in field and pot experiments.

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Streptomyces soil isolates exhibiting the unique ability to oxidize atmospheric H(2) possess genes specifying a putative high-affinity [NiFe]-hydrogenase. This study was undertaken to explore the taxonomic diversity and the ecological importance of this novel functional group. We propose to designate the genes encoding the small and large subunits of the putative high-affinity hydrogenase hhyS and hhyL, respectively.

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Uptake of molecular hydrogen (H2) by soil is a biological reaction responsible for approximately 80% of the global loss of atmospheric H2. Indirect evidence obtained over the last decades suggests that free soil hydrogenases with an unusually high affinity for H2 are carrying out the reaction. This assumption has recently been challenged by the isolation of Streptomyces sp.

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Lasiurus sindicus is a highly nutritive, drought-tolerant, perennial grass that is endemic to the Thar Desert of Rajasthan, India. Analysis of 16S rRNA coding genes of the bacterial isolates enriched in nitrogen-free semisolid medium, from the surface-sterilized roots of L. sindicus, showed predominance of Gram-negative over Gram-positive bacteria.

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Salinity stress inhibits the growth and nitrogen fixation ability of the plant growth-promoting rhizobacterium Azospirillum brasilense. Five strains of A. brasilense were isolated from the rhizosphere of Indian cereals and grasses and identified on the basis of their phenotypic features and 16S rRNA gene sequence.

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A non-pigmented, motile, Gram-negative bacterium designated MTCC 4195(T) was isolated from surface-sterilized seeds and plant tissue from deep-water rice (Oryza sativa) cultivated in Suraha Tal Lake in northern India. This isolate was shown to reinfect and colonize deep-water rice endophytically. The highest level of 16S rRNA sequence similarity (96.

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Article Synopsis
  • Bacterial symbionts in nitrogen-fixing nodules of Mimosa pudica from North and South India matched closely with Ralstonia taiwanensis based on carbon-source usage and 16S rDNA sequences.
  • Isolates from both regions displayed similar ARDRA patterns, but showed differences with the AluI enzyme, indicating genetic variation between the two populations.
  • Analysis of nifH sequences suggests that nitrogen-fixing genes in these bacteria may have been transferred laterally from alpha-rhizobia to R. taiwanensis, while also indicating the existence of functional dinitrogenase reductase, though nitrogen-fixing activity was not observed under N-free conditions.
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Colonization ability of the two endophytic bacteria, isolated from surface sterilized seeds of Jaisurya variety of deep-water rice viz., Pantoea sp. and Ochrobactrum sp.

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