title: Artificial citrate operon confers mineral phosphate solubilization ability to diverse fluorescent pseudomonads.
abstract: Citric acid is a strong acid with good cation chelating ability and can be very efficient in solubilizing mineral phosphates. Only a few phosphate solubilizing bacteria and fungi are known to secrete citric acids. In this work, we incorporated artificial citrate operon containing NADH insensitive citrate synthase (gltA1) and citrate transporter (citC) genes into the genome of six-plant growth promoting P. fluorescens strains viz., PfO-1, Pf5, CHAO1, P109, ATCC13525 and Fp315 using MiniTn7 transposon gene delivery system. Comprehensive biochemical characterization of the genomic integrants and their comparison with plasmid transformants of the same operon in M9 minimal medium reveals the highest amount of ∼7.6±0.41 mM citric and 29.95±2.8 mM gluconic acid secretion along with ∼43.2±3.24 mM intracellular citrate without affecting the growth of these P. fluorescens strains. All genomic integrants showed enhanced citric and gluconic acid secretion on Tris-Cl rock phosphate (TRP) buffered medium, which was sufficient to release 200-1000 µM Pi in TRP medium. This study demonstrates that MPS ability could be achieved in natural fluorescent pseudomonads by incorporation of artificial citrate operon not only as plasmid but also by genomic integration.
authors.affiliation: Department of Biochemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India.
authors.forename: Hemanta
authors.initials: H
authors.lastname: Adhikary
authors.affiliation: Department of Biochemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India.
authors.forename: Paulomi B
authors.initials: PB
authors.lastname: Sanghavi
authors.affiliation: Department of Biochemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India.
authors.forename: Silviya R
authors.initials: SR
authors.lastname: Macwan
authors.affiliation: Department of Microbiology and Biotechnology Centre, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India.
authors.forename: Gattupalli
authors.initials: G
authors.lastname: Archana
authors.affiliation: Department of Biochemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India.
authors.forename: G
authors.initials: G
authors.lastname: Naresh Kumar
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002950:Citrate (si)-Synthase / Q000235:genetics / Q000378:metabolism; D019343:Citric Acid / Q000378:metabolism*; D015870:Gene Expression; D023061:Gene Order; D005947:Glucose / Q000378:metabolism; D008903:Minerals / Q000378:metabolism*; D009876:Operon; D010710:Phosphates / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D011551:Pseudomonas fluorescens / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D008903:Minerals; D010710:Phosphates; C020723:citrate-binding transport protein; D019343:Citric Acid; D002950:Citrate (si)-Synthase; D005947:Glucose