Salubrità degli agroecosistemi: processi chimici, biochimici e biologici che regolano la mobilità dell'As nei comparti suolo-acqua-pianta

Metabolic reactions mediated by microorganisms are responsible of a consistent part of arsenic mobilization/immobilization processes and speciation in soil and water.



The research proposed by this research unit has the aim to characterise bacterial populations involved in the arsenic cycle in water-soil compartments during modifications of redox potential conditions and to characterise arsenite oxidising strains for implementation of bio-based processes for decontamination of drinking-water supplies. For these purposes, bacterial community involved specifically in arsenic, iron and manganese cycles will be studied by means of molecular advanced tools (i.e: denaturing gradient gel electrophoresis, Pyrotag sequencing and quantitative real time PCR) in rice fiel soils subjected to oxic/anoxic conditions. Arsenite oxidation by the isolated bacterial strains will be evaluated in the presence of Zero Valent iron (granular and nano sized) and low cost nanomaterials (anionic clays, layered double hydroxides [LDHs]). Chemical speciation of arsenic in cultural broths will be performed using solid phase extraction cartridges. Determination of total arsenic, arsenite and arsenate will be conducted by inductively coupled plasma mass spectrometry (ICP-MS).



The expected results of this research are: i) microbial populations relevant for arsenic cycle at rice fiels in different redox conditions; ii) determination of environmental conditions that enhance the activity of arsenic immobilizing bacteria as natural means to attenuate arsenic mobilization in soil, water and plant; iii) selection of AsIII oxidizing bacterial strains to be used as biocatalizers in the first step of arsenic removal process from water and the improvement of their activity for treatment of drinking water supplies.