Artificial Citrate Operon Confers Mineral Phosphate Solubilization Ability to Diverse Fluorescent Pseudomonads

Adhikary, Hemanta; Sanghavi, Paulomi; Macwan, Silviya R.; Archana, G.

doi:10.1371/journal.pone.0107554

Cited by 14 publications

(5 citation statements)

References 49 publications

(52 reference statements)

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“…The recent research demonstrated that citric acid secreted by PSB strains can improve their P-solubilizing activity. Researchers incorporated artificial citrate operon, containing NADH insensitive citrate synthase (gltA1) and citrate transporter (citC) genes, into the genomes of Pseudomonas fluorescens (Adhikary et al, 2014) and Enterobacter hormaechei strains (Yadav et al, 2014), founding that the transformants secreted more citric acids than the native strains, and released more soluble P in the mediums. Further studies are required for confirming which organic acids reduce the pH of the medium.…”

Section: Discussionmentioning

confidence: 99%

Selection and evaluation of phosphate-solubilizing bacteria from grapevine rhizospheres for use as biofertilizers

Ling

Liu

Cheng

et al. 2017

Span. j. agric. res.

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Phosphate-solubilizing bacteria (PSB) have the ability to solubilize insoluble phosphorus (P) and release soluble P. Extensive research has been performed with respect to PSB isolation from the rhizospheres of various plants, but little is known about the prevalence of PSB in the grapevine rhizosphere. In this study, we aimed to isolate and identify PSB from the grapevine rhizosphere in five vineyards of Northwest China, to characterize their plant-growth-promoting (PGP) traits, evaluate the effect of stress on their phosphate-solubilizing activity (PSA), and test their ability to stimulate the growth of Vitis vinifera L. cv. Cabernet Sauvignon. From the vineyard soils, 66 PSB isolates were screened, and 10 strains with high PSA were identified by 16S rRNA sequencing. Sequence analysis revealed that these 10 strains belonged to 4 genera and 5 species: Bacillus aryabhattai, B. megaterium, Klebsiella variicola, Stenotrophomonas rhizophila, and Enterobacter aerogenes. The selected PSB strains JY17 (B. aryabhattai) and JY22 (B. aryabhattai) were positive for multiple PGP traits, including nitrogen fixation and production of indole acetic acid (IAA), siderophores, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, chitinase, and protease. JY17 and JY22 showed strong PSA under stress conditions of high pH, high salt, and high temperature. Therefore, these two isolates can be used as biofertilizers in saline-alkaline soils. The inoculation with PSB significantly facilitated the growth of V. vinifera cv. Cabernet Sauvignon under greenhouse conditions. Use of these PSB as biofertilizers will increase the available P content in soils, minimize P-fertilizer application, reduce environmental pollution, and promote sustainable agriculture.Additional key words: promote plant growth; inorganic phosphate; stress conditions; saline-alkaline soil; Vitis vinifera L. cv. Cabernet SauvignonAbbreviations used: ACC (1-aminocyclopropane-1-carboxylate); CAS (chrome azurol S); DF (Dworkin-Foster); GADH (gluconate dehydrogenase); IAA (indole acetic acid); NBRIP (National Botanical Research Institute's phosphate); PGP (plant-growthpromoting); PQQ-GDH (pyrroloquinoline quinone-dependent glucose dehydrogenase); PSA (phosphate-solubilizing activity); PSB (phosphate-solubilizing bacteria); TCP (tricalcium phosphate).Authors' contributions: ML drafted the manuscript; XL made critical revision of the manuscript for important intellectual content; BSC and XLM acquired, analyzed and interpreted data; XTL coordinated the research project; XFZ performed statistical analysis; YLJ and ZM proposed revision suggestions; YLF supervised the work.Citation: Liu, M.; Liu, X.; Cheng, B. S.; Ma, X. L.; Lyu, X. T.; Zhao, X. F.; Ju, Y. L.; Min, Z.; Fang, Y. L. (2016). Selection and evaluation of phosphate-solubilizing bacteria from grapevine rhizospheres for use as biofertilizers.

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Section: Discussionmentioning

confidence: 99%

Selection and evaluation of phosphate-solubilizing bacteria from grapevine rhizospheres for use as biofertilizers

Ling

Liu

Cheng

et al. 2017

Span. j. agric. res.

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“…Overexpression of Synechococcus elongatus PCC 6301 phosphoenolpyruvate carboxylase (ppc) in P. fluorescens was shown to enhance glucose metabolism, increasing production of gluconate, pyruvate and acetate, which mildly improved Pi solubilisation [59]. An artificial citrate operon containing an E. coli derived NADH-insensitive citrate synthase (gltA1) and citrate transporter (citC) has also been successfully cloned and integrated into the genomes of six PGP P. fluorescens strains, elevating secretion of citric and gluconic acids and increasing solubilisation of mineral phosphate [60]. Although the above-mentioned bacteria mobilise P under laboratory conditions, artificially enhanced organic acid production and secretion demands substantial inputs of C, likely exceeding what is available in most rhizospheres.…”

Section: Phosphate Solubilisationmentioning

confidence: 99%

Engineering rhizobacteria for sustainable agriculture

2020

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Exploitation of plant growth promoting (PGP) rhizobacteria (PGPR) as crop inoculants could propel sustainable intensification of agriculture to feed our rapidly growing population. However, field performance of PGPR is typically inconsistent due to suboptimal rhizosphere colonisation and persistence in foreign soils, promiscuous host-specificity, and in some cases, the existence of undesirable genetic regulation that has evolved to repress PGP traits. While the genetics underlying these problems remain largely unresolved, molecular mechanisms of PGP have been elucidated in rigorous detail. Engineering and subsequent transfer of PGP traits into selected efficacious rhizobacterial isolates or entire bacterial rhizosphere communities now offers a powerful strategy to generate improved PGPR that are tailored for agricultural use. Through harnessing of synthetic plant-to-bacteria signalling, attempts are currently underway to establish exclusive coupling of plant-bacteria interactions in the field, which will be crucial to optimise efficacy and establish biocontainment of engineered PGPR. This review explores the many ecological and biotechnical facets of this research.

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“…Other studies have introduced P solubilization genes into plant-associated hosts (20–22), but these typically rely on plasmids which are genetically unstable (23). Genomic integrants have been created for a single phosphate solubilization pathway (24), but the resulting strains were not tested for activity in plants.…”

Section: Introductionmentioning

confidence: 99%

Engineered Root Bacteria Release Plant-Available Phosphate from Phytate

Shulse

Chovatia

Agosto

et al. 2019

Appl Environ Microbiol

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Microorganisms that release plant-available phosphate from natural soil phosphate stores may serve as biological alternatives to costly and environmentally damaging phosphate fertilizers. To explore this possibility, we engineered a collection of root bacteria to release plant-available orthophosphate from phytate, an abundant phosphate source in many soils. We identified 82 phylogenetically diverse phytase genes, refactored their sequences for optimal expression in Proteobacteria, and then synthesized and engineered them into the genomes of three root-colonizing bacteria. Liquid culture assays revealed 41 engineered strains with high levels of phytate hydrolysis. Among these, we identified 12 strains across three bacterial hosts that confer a growth advantage on the model plant Arabidopsis thaliana when phytate is the sole phosphate source. These data demonstrate that DNA synthesis approaches can be used to generate plant-associated strains with novel phosphate-solubilizing capabilities. IMPORTANCE Phosphate fertilizers are essential for high-yield agriculture yet are costly and environmentally damaging. Microbes that release soluble phosphate from naturally occurring sources in the soil are appealing, as they may reduce the need for such fertilizers. In this study, we used synthetic biology approaches to create a collection of engineered root-associated microbes with the ability to release phosphate from phytate. We demonstrate that these strains improve plant growth under phosphorus-limited conditions. This represents a first step in the development of phosphate-mining bacteria for future use in crop systems.

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Artificial Citrate Operon Confers Mineral Phosphate Solubilization Ability to Diverse Fluorescent Pseudomonads

Cited by 14 publications

References 49 publications

Selection and evaluation of phosphate-solubilizing bacteria from grapevine rhizospheres for use as biofertilizers

Selection and evaluation of phosphate-solubilizing bacteria from grapevine rhizospheres for use as biofertilizers

Engineering rhizobacteria for sustainable agriculture

Engineered Root Bacteria Release Plant-Available Phosphate from Phytate

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