Quantification of bacterial RubisCO genes in soils by cbbL targeted real-time PCR

Soils harbor a high diversity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) large subunit coding genes (cbbL). Real-time PCR was used to quantify this gene in differently managed agricultural soils and soil microhabitats. We developed primers and a TaqMan probe that target the "red-like" RubisCO gene cbbL. Primers and probe were developed based on cbbL sequences of selected bacterial pure cultures and of environmental clones. The amount of cbbL copies in the investigated soils were detected in the range of 6.8x10(6) to 3.4x10(7) "red-like" cbbL copies/g soil. The cbbL genes could be located entirely in the clay and silt fraction, while the coarse sand fractions revealed no detectable level of bacterial RubisCO genes. These results indicate that bacteria with RubisCO coding genes are numerous and widespread in soils, however the functional implication of this gene in soils is not yet clear.