The soil dehydrogenase (DHA) activity was measured by monitoring the rate of the reduction of triphenyl tetrazolium chloride (TTC) to triphenyl formazan (TPF), as described by Oliveira et al.37 (link), with some modifications. TPF was detected using a spectrophotometer (UV-2550, Shimadzu) at 485 nm after a dark incubation for 24 h and expressed in μg TPF d·g−1 of dry soil 24 h−1.
The bacterial biomass was analysed using the real-time PCR of the 16S rRNA gene; this was performed with the ABI Prism 7000 Real-Time PCR Detection System (Applied Biosystems, USA) using SYBR Premix Ex Taq II (2×) and ROX Reference Dye (50×) (Takara, China). A standard curve was produced using genomic DNA extracted from E. coli. as a template to quantify the total number of bacterial 16S rRNA gene copies. The primers used for amplification of the 16S rRNA genes were 8F (5′-GAGAGTTTGATCCTGGCTCAG-3′) and 518R (5′-ATTACCGCGGCTGCTGG-3′). The conditions for the real-time PCR were 30 s at 95 °C and then 40 cycles of 95 °C for 15 s, 55 °C for 30 s, 72 °C for 45 s and 72 °C for 5 min.
The bacterial biomass was analysed using the real-time PCR of the 16S rRNA gene; this was performed with the ABI Prism 7000 Real-Time PCR Detection System (Applied Biosystems, USA) using SYBR Premix Ex Taq II (2×) and ROX Reference Dye (50×) (Takara, China). A standard curve was produced using genomic DNA extracted from E. coli. as a template to quantify the total number of bacterial 16S rRNA gene copies. The primers used for amplification of the 16S rRNA genes were 8F (5′-GAGAGTTTGATCCTGGCTCAG-3′) and 518R (5′-ATTACCGCGGCTGCTGG-3′). The conditions for the real-time PCR were 30 s at 95 °C and then 40 cycles of 95 °C for 15 s, 55 °C for 30 s, 72 °C for 45 s and 72 °C for 5 min.