Influence of As and P Uptake On Arsenic Tolerance in Bacteria and Arsenic-Hyperaccumulator Pteris Vittata L.

Influence of As and P uptake on arsenic tolerance in bacteria and arsenic-hyperaccumulator
Pteris vittata L

Piyasa Ghosh1*, Lena Q. Ma¹ and Bala Rathinasabapathi^2
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% As
in its biomass, making it a viable candidate for phytoremediation of arsenic contaminated sites.
P. vittata is capable of extracting As from both soluble and insoluble forms due to composite
action of the plant roots and rhizosphere microorganisms. Seven As-resistant bacteria (ARB;
tolerant up to 10 mM AsV) from 3 genera were isolated from the rhizosphere soils. As AsV and
P are chemical analogs they affect the uptake of each other. We tested the influence of different
AsV concentrations of 0.1 and 1 mM AsV on P uptake, utilization and AsV reduction rates and
vice versa. Bacteria took up 3-8 times more P in presence of 1 mM AsV than in no AsV
condition due to As-induced P uptake. We found that increase in P. vittata root biomass from
1.5–2.2 to 3.4–4.2 g/plant dw by ARB and As was associated with As-induced plant P uptake. In
bacteria we have also found that higher P concentration in the bacterial medium can lower the
uptake of AsV, resulting in less AsV reduction to AsIII. So, in presence of P, plants and bacteria
may be more tolerant to As. In contaminated sites As-resistant rhizosphere bacteria can aid plant
growth and enhance phytoextraction of As-contaminated soil.

Keywords: P. vittata rhizosphere, Arsenic resistant rhizobacteria, As-induced P uptake.

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