A calibrated bacterial suspension is transferred to a well of sterile Multiscreen microplate (Millipore Ò ) containing sterile biotite particles and a nutritive solution (BHm medium), lacking iron and supplemented with a carbon substrate (2 g/L).
After 48 h incubation at 25 C with constant shaking, the liquid of each well is filtered at 0.22 m M by centrifugation.
To assess biotite weathering (1), the filtrates are recovered in a new microplate, containing Ferrospectral for Fe quantification and bromocresol green for pH measurement.
The amounts of Fe and protons released are measured at A 595nm (2) and compared with a calibration curve.
This corresponds to the mineral-weathering potential of each bacterial isolate (Uroz et al., 2007). B. Microcosm experiments.
After 6 weeks of growth in a greenhouse, the roots of Scots pine seedlings ( P. sylvestris ), inoculated or not with a mycorrhizal fungus, are washed in sterile ultrapure water to remove adhering growth substrate.
Seedlings are weighed individually.
The seedlings are then introduced in sterile microcosms containing a mixture of biotite (0.5 e 1 mm diameter) and quartz (0.5 e 2 mm).
The seedlings are fed by a deficient nutrient solution devoid of potassium and magnesium (these inorganic nutrients are only present into the biotite) through a peristaltic pump.
Then a concentration of 4 Â 10 7 CFU/mL of bacterial inoculum is added.
After 80 days, all pine seedlings are sampled to observe root morphology and to quantify their final biomass and mineral content and the weathering budget is determined according to Calvaruso et al. (2006).
(For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article).
A calibrated bacterial suspension is transferred to a well of sterile Multiscreen microplate (Millipore Ò ) containing sterile biotite particles and a nutritive solution (BHm medium), lacking iron and supplemented with a carbon substrate (2 g/L).After 48 h incubation at 25 C with constant shaking, the liquid of each well is filtered at 0.22 m M by centrifugation. To assess biotite weathering (1), the filtrates are recovered in a new microplate, containing Ferrospectral for Fe quantification and bromocresol green for pH measurement. The amounts of Fe and protons released are measured at A 595nm (2) and compared with a calibration curve. This corresponds to the mineral-weathering potential of each bacterial isolate (Uroz et al., 2007). B. Microcosm experiments. After 6 weeks of growth in a greenhouse, the roots of Scots pine seedlings ( P. sylvestris ), inoculated or not with a mycorrhizal fungus, are washed in sterile ultrapure water to remove adhering growth substrate. Seedlings are weighed individually. The seedlings are then introduced in sterile microcosms containing a mixture of biotite (0.5 e 1 mm diameter) and quartz (0.5 e 2 mm). The seedlings are fed by a deficient nutrient solution devoid of potassium and magnesium (these inorganic nutrients are only present into the biotite) through a peristaltic pump. Then a concentration of 4 Â 10 7 CFU/mL of bacterial inoculum is added. After 80 days, all pine seedlings are sampled to observe root morphology and to quantify their final biomass and mineral content and the weathering budget is determined according to Calvaruso et al. (2006). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article).
การแปล กรุณารอสักครู่..
