Illumina sequencing of dsrB cDNA
RNA extracts were reversely transcribed and amplified using the one-step RT-PCR system (Access RT-PCR, Promega). PCR amplification of dsrB was performed using the primers DSR1728F and DSR4R. In a second PCR, purified PCR product was used as template by M13-primers elongated at each side with a 6-bp long barcode.