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Lowland rice fields of West Africa (Ivory Coast) and South Asia (Thailand) are affected by ferrous toxicity or salinity, respectively, and their soil waters contain large amounts of ferrous iron, depending on reducing irrigation condition and suggesting occurrence of bacterial reducing processes. To determine the involvement, dynamic and activities of bacterial communities in Fe(III) reduction and mobilization during anaerobic degradation and mineralization of soil organic matter (SOM), different experiments and analyses have been performed. Results demonstrated that the utilization of SOM as sole carbon, nutrient and energy sources favored the presence of large bacterial communities: facultative anaerobic and anaerobic bacteria, Fe(III)-reducing bacteria (FeRB) (fermentative and Fe respiring), sulfate reducing bacteria (SRB) which are involved in carbon, nitrogen, iron and sulfur cycling. The larger functional diversity is observed in the Ivory Coast paddy soils containing larger amounts of organic matter and sulfur compounds. These communities contained complementary populations (chemoorganotrophic, chemolitotrophic, aerobic, facultative anaerobic and anaerobic) that can be active at different steps of iron solubilization with simultaneous organic matter mineralization. Our results indicate that the pH controlled by bacterial activity, the nature much more than the content of organic matter, and consequently the structure and activity of bacterial communities influence significantly the availability and dynamic of iron in paddy fields which affect the soil quality. [ABSTRACT FROM AUTHOR]

This study aimed to determine the relationship between cell adhesion and pyrite corrosion. In order to determine cell adhesion rates, a new in vivo imaging procedure was developed with CLSM. Total bacteria coverage rates remained low (< 14%). Adsorption isotherms pointed out two types of cell adhesion sites. Bacteria adhered mainly to corrosion pittings walls with a higher affinity. They favour the formation of deep corrosion pits by maintaining short-range electronic circulations and they avoid surface passivation. This study completes the common model of bio-corrosion of pyrite and we propose to refine the direct/indirect model by proximal and distal approaches. [ABSTRACT FROM AUTHOR]