Arsenic-Resistant Bacteria Helped in Solubilizing P From Insoluble Minerals and Enhancing Plant Growth.

Arsenic-resistant bacteria helped in solubilizing P from insoluble minerals and enhancing plant growth

Piyasa Ghosh^1*, Lena Q. Ma¹ and Bala Rathinasabapathi²

¹ Soil and Water Science Department, ² Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, United States

 

Arsenic hyperaccumulator Pteris vittata L (Chinese Brake fern) may accumulate up to 2.3% arsenic in its biomass, making it a viable candidate for phytoremediation of arsenic contaminated sites. P. vittata is capable of extracting arsenic from both soluble and insoluble forms, mainly due to the solubilizing effect of the rhizoshere microorganisms. Seven siderophore producing arsenic-resistant bacteria were isolated from the rhizosphere soils. Previous research has shown that the siderophores released arsenic ions from FeAsO₄/AlAsO₄ minerals, which increased arsenic uptake by the arsenic-hyperaccumulating fern Pteris vittata.  We tested the solubilization ability of the same bacteria in releasing P from insoluble inorganic soil minerals like FePO₄ and rock phosphate as well as organic soil P reserve of phytate. To verify that siderophores are responsible for releasing P from FePO₄, we tested the solubilization ability of two mutants of Pseudomonas fluorescens Pf5, which were impaired in siderophore production compared to wild type. We tested the hypothesis in tomato where P-starved plants were exposed to insoluble FePO₄ and phytate with and without bacterial spent medium addition. To reduce the demineralization of P released from the minerals we introduced spent growth medium of the bacteria, which contained the water-soluble siderophores in our experimental system. In future these phosphate solubilizing bacteria may help in improving plant nutrition in field applications.

Keywords: P solubilization, Arsenic resistant rhizobacteria, siderophores.

*Presenting author, 2176B McCarty Hall A, Gainesville, Fl 32611, 352-392-8663, piyasaghosh@ufl.edu