Isolation, Biochemical and Genomic Characterization of Glyphosate Tolerant Bacteria to Perform Microbe-Assisted Phytoremediation

The large-scale use of the herbicide glyphosate leads to growing ecotoxicological and human health concerns. Microbe-assisted phytoremediation arises as a good option to remove, contain, or degrade glyphosate from soils and waterbodies, and thus avoid further spreading to non-target areas. To achieve this, availability of plant-colonizing, glyphosate-tolerant and -degrading strains is required and at the same time, it must be linked to plant-microorganism interaction studies focusing on a substantive ability to colonize the roots and degrade or transform the herbicide. In this work, we isolated bacteria from a chronically glyphosate-exposed site in Argentina, evaluated their glyphosate tolerance using the minimum inhibitory concentration assay, their in vitro degradation potential, their plant growth-promotion traits, and performed whole genome sequencing to gain insight into the application of a phytoremediation strategy to remediate glyphosate contaminated agronomic soils. Twenty-four soil and root-associated bacterial strains were isolated. Sixteen could grow using glyphosate as the sole source of phosphorous. As shown in MIC assay, some strains tolerated up to 10000 mg kg–1 of glyphosate. Most of them also demonstrated a diverse spectrum of in vitro plant growth-promotion traits, confirmed in their genome sequences. Two representative isolates were studied for their root colonization. An isolate of Ochrobactrum haematophilum exhibited different colonization patterns in the rhizoplane compared to an isolate of Rhizobium sp. Both strains were able to metabolize almost 50% of the original glyphosate concentration of 50 mg l–1 in 9 days. In a microcosms experiment with Lotus corniculatus L, O. haematophilum performed better than Rhizobium, with 97% of glyphosate transformed after 20 days. The results suggest that L. corniculatus in combination with to O. haematophilum can be adopted for phytoremediation of glyphosate on agricultural soils. An effective strategy is presented of linking the experimental data from the isolation of tolerant bacteria with performing plant-bacteria interaction tests to demonstrate positive effects on the removal of glyphosate from soils.

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Priming of Plant Growth Promotion by Volatiles of Root-AssociatedMicrobacteriumspp.

Applied and Environmental Microbiology ◽

10.1128/aem.01865-18 ◽

2018 ◽

Vol 84 (22) ◽

Cited By ~ 17

Author(s):

Viviane Cordovez ◽

Sharella Schop ◽

Kees Hordijk ◽

Hervé Dupré de Boulois ◽

Filip Coppens ◽

...

Keyword(s):

Plant Growth ◽

Volatile Compounds ◽

Plant Growth Promotion ◽

Large Scale ◽

Plant Biomass ◽

Growth Promotion ◽

Shoot Biomass ◽

Content Type ◽

Prolonged Contact

ABSTRACTVolatile compounds produced by plant-associated microorganisms represent a diverse resource to promote plant growth and health. Here, we investigated the effect of volatiles from root-associatedMicrobacteriumspecies on plant growth and development. Volatiles of eight strains induced significant increases in shoot and root biomass ofArabidopsisbut differed in their effects on root architecture.Microbacteriumstrain EC8 also enhanced root and shoot biomass of lettuce and tomato. Biomass increases were also observed for plants exposed only briefly to volatiles from EC8 prior to transplantation of the seedlings to soil. These results indicate that volatiles from EC8 can prime plants for growth promotion without direct and prolonged contact. We further showed that the induction of plant growth promotion is tissue specific; that is, exposure of roots to volatiles from EC8 led to an increase in plant biomass, whereas shoot exposure resulted in no or less growth promotion. Gas chromatography–quadrupole time of flight mass spectometry (GC–QTOF-MS) analysis revealed that EC8 produces a wide array of sulfur-containing compounds, as well as ketones. Bioassays with synthetic sulfur volatile compounds revealed that the plant growth response to dimethyl trisulfide was concentration-dependent, with a significant increase in shoot weight at 1 μM and negative effects on plant biomass at concentrations higher than 1 mM. Genome-wide transcriptome analysis of volatile-exposedArabidopsisseedlings showed upregulation of genes involved in assimilation and transport of sulfate and nitrate. Collectively, these results show that root-associatedMicrobacteriumprimes plants, via the roots, for growth promotion, most likely via modulation of sulfur and nitrogen metabolism.IMPORTANCEIn the past decade, various studies have described the effects of microbial volatiles on other (micro)organismsin vitro, but their broad-spectrum activityin vivoand the mechanisms underlying volatile-mediated plant growth promotion have not been addressed in detail. Here, we revealed that volatiles from root-associated bacteria of the genusMicrobacteriumcan enhance the growth of different plant species and can prime plants for growth promotion without direct and prolonged contact between the bacterium and the plant. Collectively, these results provide new opportunities for sustainable agriculture and horticulture by exposing roots of plants only briefly to a specific blend of microbial volatile compounds prior to transplantation of the seedlings to the greenhouse or field. This strategy has no need for large-scale introduction or root colonization and survival of the microbial inoculant.

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The Effects of Plant Growth-Promoting Bacteria with Biostimulant Features on the Growth of a Local Onion Cultivar and a Commercial Zucchini Variety

Agronomy ◽

10.3390/agronomy11050888 ◽

2021 ◽

Vol 11 (5) ◽

pp. 888

Author(s):

Giorgia Novello ◽

Patrizia Cesaro ◽

Elisa Bona ◽

Nadia Massa ◽

Fabio Gosetti ◽

...

Keyword(s):

Plant Growth ◽

Growth Promotion ◽

Global Market ◽

Plant Growth Promoting Bacteria ◽

Bacterial Strains ◽

Mineral Concentration ◽

Positive Effects ◽

Plant Growth Promoting ◽

Onion Cultivar ◽

Growth Promoting

The reduction of chemical inputs due to fertilizer and pesticide applications is a target shared both by farmers and consumers in order to minimize the side effects for human and environmental health. Among the possible strategies, the use of biostimulants has become increasingly important as demonstrated by the fast growth of their global market and by the increased rate of registration of new products. In this work, we assessed the effects of five bacterial strains (Pseudomonas fluorescens Pf4, P. putida S1Pf1, P. protegens Pf7, P. migulae 8R6, and Pseudomonas sp. 5Vm1K), which were chosen according to their previously reported plant growth promotion traits and their positive effects on fruit/seed nutrient contents, on a local onion cultivar and on zucchini. The possible variations induced by the inoculation with the bacterial strains on the onion nutritional components were also evaluated. Inoculation resulted in significant growth stimulation and improvement of the mineral concentration of the onion bulb, induced particularly by 5Vm1K and S1Pf1, and in different effects on the flowering of the zucchini plants according to the bacterial strain. The present study provides new information regarding the activity of the five plant growth-promoting bacteria (PGPB) strains on onion and zucchini, two plant species rarely considered by the scientific literature despite their economic relevance.

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EFFICACY OF RHIZOBACTERIA ON PLANT GROWTH PROMOTION AND DISEASE SUPPRESSION IN VITRO

Acta Horticulturae ◽

10.17660/actahortic.2012.961.69 ◽

2012 ◽

pp. 525-532 ◽

Cited By ~ 1

Author(s):

S. Velivelli ◽

E. O'Herlihy ◽

B. Janczura ◽

B. Doyle Prestwich ◽

J. Ghyselinck ◽

...

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Disease Suppression

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Exploitation of endophytic Pseudomonas sp. for plant growth promotion and colonization in rice

Journal of Applied and Natural Science ◽

10.31018/jans.v9i3.1359 ◽

2017 ◽

Vol 9 (3) ◽

pp. 1310-1316

Author(s):

Gurjot Kaur ◽

Poonam Sharma ◽

Deepika Chhabra ◽

Kailash Chand ◽

Gurjit Singh Mangat

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Acc Deaminase ◽

Pseudomonas Sp ◽

Bacterial Isolates ◽

Pgp Traits ◽

P Solubilization ◽

Fluorescent Pigment

The present investigation was carried out to exploit bacterial endophytes associated with root and leaf tissue of rice plant for plant growth promotion (PGP) and colonization study in vitro. Total 10 endophytic bacterial isolates (Pseudomonas sp.) were evaluate for PGP traits like P solubilization, production of Indole acetic acid (IAA), siderophore, ACC deaminase, protease, cellulase, fluorescent pigment, urease and denitrification activity. Out of 10 endophytic bacteria 30 %, 60 %, 20 %, 70 %, 10 % and 10 % were positive for siderophore, protease, cellulase, fluorescent pigment, urease and denitrification respectively. Maximum IAA production was recorded with isolate LRBLE7 (18.8 μgml-1) followed by LRBRE4 (16.0 μgml-1) and maximum P-solubilization was recorded with isolate LRBRE4 (5.8 mg 100 ml-1) followed by LRBLE7 (4.4 mg 100 ml-1). ACC deaminase production was recorded with isolate LRBLE6 (O.D=0.352 nm) followed by LRBRE5 (O.D=0.324nm). Three potential isolates (LRBRE4, LRBRE6 and LRBLE7) were selected on the basis of multiple PGP traits and were subjected to colonization study of rice seedling in vitro. Potential bacterial isolates can be exploited for improving growth and productivity in rice under sustainable management system.

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Potential for Plant Growth Promotion of Rhizobacteria Associated withSalicorniaGrowing in Tunisian Hypersaline Soils

BioMed Research International ◽

10.1155/2013/248078 ◽

2013 ◽

Vol 2013 ◽

pp. 1-13 ◽

Cited By ~ 84

Author(s):

Francesca Mapelli ◽

Ramona Marasco ◽

Eleonora Rolli ◽

Marta Barbato ◽

Hanene Cherif ◽

...

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Crop Production ◽

Denaturing Gradient Gel Electrophoresis ◽

Growth Promotion ◽

Arid Ecosystems ◽

Acetic Acid Production ◽

Halotolerant Bacteria ◽

Microbiome Composition

Soil salinity and drought are among the environmental stresses that most severely affect plant growth and production around the world. In this study the rhizospheres ofSalicorniaplants and bulk soils were collected fromSebkhetandChotthypersaline ecosystems in Tunisia. Depiction of bacterial microbiome composition by Denaturing Gradient Gel Electrophoresis unveiled the occurrence of a high bacterial diversity associated withSalicorniaroot system. A large collection of 475 halophilic and halotolerant bacteria was established fromSalicorniarhizosphere and the surrounding bulk soil, and the bacteria were characterized for the resistance to temperature, osmotic and saline stresses, and plant growth promotion (PGP) features. TwentyHalomonasstrains showed resistance to a wide set of abiotic stresses and were able to perform different PGP activitiesin vitroat 5% NaCl, including ammonia and indole-3-acetic acid production, phosphate solubilisation, and potential nitrogen fixation. By using agfp-labelled strain it was possible to demonstrate thatHalomonasis capable of successfully colonisingSalicorniaroots in the laboratory conditions. Our results indicated that the culturable halophilic/halotolerant bacteria inhabiting salty and arid ecosystems have a potential to contribute to promoting plant growth under the harsh salinity and drought conditions. These halophilic/halotolerant strains could be exploited in biofertilizer formulates to sustain crop production in degraded and arid lands.

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Disease Control and Plant Growth Promotion (PGP) of Selected Bacterial Strains in Phaseolus vulgaris

Biological Nitrogen Fixation and Beneficial Plant-Microbe Interaction ◽

10.1007/978-3-319-32528-6_20 ◽

2016 ◽

pp. 237-245 ◽

Cited By ~ 2

Author(s):

Miriam Memenza ◽

Elvia Mostacero ◽

Félix Camarena ◽

Doris Zúñiga

Keyword(s):

Phaseolus Vulgaris ◽

Plant Growth ◽

Disease Control ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Bacterial Strains

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Evaluation of bacteria isolated from rice for plant growth promotion and biological control of seedling disease of rice

Canadian Journal of Microbiology ◽

10.1139/w01-097 ◽

2001 ◽

Vol 47 (10) ◽

pp. 916-924 ◽

Cited By ~ 71

Author(s):

Tika B Adhikari ◽

C M Joseph ◽

Guoping Yang ◽

Donald A Phillips ◽

Louise M Nelson

Keyword(s):

Biological Control ◽

Plant Growth ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Disease Incidence ◽

Control Plant ◽

16S Rrna Genes ◽

Rrna Genes ◽

Bacterial Strains ◽

Seedling Disease

Of 102 rhizoplane and endophytic bacteria isolated from rice roots and stems in California, 37% significantly (P [Formula: see text] 0.05) inhibited the growth in vitro of two pathogens, Achlya klebsiana and Pythium spinosum, causing seedling disease of rice. Four endophytic strains were highly effective against seedling disease in growth pouch assays, and these were identified as Pseudomonas fluorescens (S3), Pseudomonas tolaasii (S20), Pseudomonas veronii (S21), and Sphingomonas trueperi (S12) by sequencing of amplified 16S rRNA genes. Strains S12, S20, and S21 contained the nitrogen fixation gene, nifD, but only S12 was able to reduce acetylene in pure culture. The four strains significantly enhanced plant growth in the absence of pathogens, as evidenced by increases in plant height and dry weight of inoculated rice seedlings relative to noninoculated rice. Three bacterial strains (S3, S20, and S21) were evaluated in pot bioassays and reduced disease incidence by 50%73%. Strain S3 was as effective at suppressing disease at the lowest inoculum density (106 CFU/mL) as at higher density (108 CFU/mL or undiluted suspension). This study indicates that selected endophytic bacterial strains have potential for control of seedling disease of rice and for plant growth promotion.Key words: biological control, plant growth promotion, endophytes, rice, seedling disease.

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Comparison of the plant growth-promotion performance of a consortium of Bacilli inoculated as endospores or as vegetative cells

FEMS Microbiology Ecology ◽

10.1093/femsec/fiz147 ◽

2019 ◽

Vol 95 (11) ◽

Cited By ~ 4

Author(s):

Isha Hashmi ◽

Christophe Paul ◽

Andrej Al-Dourobi ◽

Frederic Sandoz ◽

Priscilla Deschamps ◽

...

Keyword(s):

Seed Germination ◽

Plant Growth ◽

Positive Impact ◽

Growth Promotion ◽

Soil Microbial Communities ◽

Vegetative Cells ◽

Single Strain ◽

Positive Effects ◽

Pot Experiments

ABSTRACT The effect of three plant growth-promoting Bacillus strains inoculated either alone or as a consortium was tested on oat (Avena sativa) growth. The bioinoculants were applied as vegetative cells or endospores at low cell densities on the seeds and their effect was tested in sterile in vitro conditions, pot experiments, and a field trial. The in vitro seed germination assay showed that both individual bacterial inocula and bacterial consortia had positive effects on seed germination. Greenhouse pot experiments with sterile and non-sterile soil showed that consortia increased the total dry biomass of oat plants as compared to single strain inoculation and uninoculated controls. However, the positive impact on plant growth was less prominent when the bioinoculated strains had to compete with native soil microbes. Finally, the field experiment demonstrated that the consortium of vegetative cells was more efficient in promoting oat growth than the endospore consortium and the uninoculated control. Moreover, both consortia successfully colonized the roots and the rhizosphere of oat plants, without modifying the overall structure of the autochthonous soil microbial communities.

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Diversity, Phylogeny and Plant Growth Promotion Traits of Nodule Associated Bacteria Isolated from Lotus parviflorus

Microorganisms ◽

10.3390/microorganisms8040499 ◽

2020 ◽

Vol 8 (4) ◽

pp. 499 ◽

Cited By ~ 2

Author(s):

Ricardo Soares ◽

Jesús Trejo ◽

Maria J. Lorite ◽

Etelvina Figueira ◽

Juan Sanjuán ◽

...

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Root Nodules ◽

Nifh Gene ◽

Bacterial Strains ◽

Lytic Enzymes ◽

Taxonomic Assignment ◽

Pgp Traits ◽

Associated Bacteria

Lotus spp. are widely used as a forage to improve pastures, and inoculation with elite rhizobial strains is a common practice in many countries. However, only a few Lotus species have been studied in the context of plant-rhizobia interactions. In this study, forty highly diverse bacterial strains were isolated from root nodules of wild Lotus parviflorus plants growing in two field locations in Portugal. However, only 10% of these isolates could nodulate one or more legume hosts tested, whereas 90% were thought to be opportunistic nodule associated bacteria. Phylogenetic studies place the nodulating isolates within the Bradyrhizobium genus, which is closely related to B. canariense and other Bradyrhizobium sp. strains isolated from genistoid legumes and Ornithopus spp. Symbiotic nodC and nifH gene phylogenies were fully consistent with the taxonomic assignment and host range. The non-nodulating bacteria isolated were alpha- (Rhizobium/Agrobacterium), beta- (Massilia) and gamma-proteobacteria (Pseudomonas, Lysobacter, Luteibacter, Stenotrophomonas and Rahnella), as well as some bacteroidetes from genera Sphingobacterium and Mucilaginibacter. Some of these nodule-associated bacteria expressed plant growth promotion (PGP) traits, such as production of lytic enzymes, antagonistic activity against phytopathogens, phosphate solubilization, or siderophore production. This argues for a potential beneficial role of these L. parviflorus nodule-associated bacteria.

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