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Front. Microbiol. | doi: 10.3389/fmicb.2018.00034

Pseudomonas rhizophila S211, a new plant growth-promoting rhizobacterium with potential in pesticide-bioremediation

  • 1Higher Institute for Biotechnology, Manouba University, Tunisia
  • 2Faculty of Sciences of Tunis, Tunis El Manar University, Tunisia
  • 3Department of Civil, Chemical, Environmental and Materials Engineering (DICAM), Università di Bologna, Italy

A number of Pseudomonas strains function as inoculants for biocontrol, biofertilization, and phytostimulation, avoiding the use of pesticides and chemical fertilizers. Here, we present a new metabolically versatile plant growth-promoting rhizobacterium, Pseudomonas rhizophila S211, isolated from a pesticide contaminated artichoke field that shows biofertilization, biocontrol and bioremediation potentialities. The S211 genome was sequenced, annotated and key genomic elements related to plant growth promotion and biosurfactant synthesis were elucidated. S211 genome comprises 5,948,515 bp with 60.4% G+C content, 5306 coding genes and 215 RNA genes. The genome sequence analysis confirmed the presence of genes involved in plant-growth promoting and remediation activities such as the synthesis of ACC deaminase, putative dioxygenases, auxin, pyroverdin, exopolysaccharide levan and rhamnolipid biosurfactant (BS). BS production by P. rhizophila S211 grown on olive mill wastewater based media was effectively optimized using a central-composite experimental design and response surface methodology. The optimum conditions for maximum BS production yield (720.80 ± 55.90 mg/L) were: 0.5% (v/v) inoculum size, 15% (v/v) olive oil mill wastewater and 40°C incubation temperature at pH 6.0 for 8 days incubation period. Biochemical and structural characterization of S211 BS by chromatography and spectroscopy studies suggested the glycolipid nature of the BS. P. rhizophila rhamnolipid was stable over a wide range of temperature (40-90°C), pH (6 to 10), and salt concentration (up to 300 mM NaCl). Due to its low-cost production, emulsification activities and high performance in solubilization enhancement of chemical pesticides, the indigenous BS-producing PGPR S211 could be used as a promising agent for environmental bioremediation of pesticide-contaminated agricultural soils.

Keywords: Pseudomonas rhizophila, plant-growth promotion rhizobacterium, Biofertilization, Phytostimulator, pesticide bioremediation, Biosurfactant production

Received: 03 Nov 2017; Accepted: 09 Jan 2018.

Edited by:

George Tsiamis, University of Patras, Greece

Reviewed by:

Spyridon Ntougias, Democritus University of Thrace, Greece
Dimitris Tsaltas, Cyprus University of Technology, Cyprus  

Copyright: © 2018 Hassen, Neifar, Cherif, Najjari, Chouchane, Chaouachi, Salah, Neili, Mosbah, Souissi, Raddadi, Fava and Cherif. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Ameur Cherif, Manouba University, Higher Institute for Biotechnology, Biotechpole Sidi Thabet, Sidi Thabet, Biotechpole Sidi Thabet, Manouba, 2020, Ariana, Tunisia, cherif.ameur@gmail.com