Transcriptomics insight into the metabolism of the toxic producing Microcystis aeruginosa PCC 7806

Microcystis is a genus of unicellular cyanobacteria capable of growing massively in freshwater ecosystems around the world and producing various toxins such as microcystins. We studied using an RNA-Seq approach the transcriptomes of three axenic strains of Microcystis, comprising the modele strain PCC 7806, selected because of their genetic potential for natural products. We assessed the expression of biosynthetic gene clusters during a 24-hour day/night cycle. The strain PCC 7806 was cultured axenically in triplicate in 1.5 L of BG11 medium under a night and day rythm. The sampling was perfomed at 8 time points, (i) at 7 am, 60 min before the transition from dark to light (t1_N); (ii) 9 am, 60 min after the transition from dark to light (t2_D); (iii) 12 am (t3-D); (iv) 4 pm (t4_D); (v) 8 pm, 1 h before the transition from light to dark (t5_D); (vi) 10 pm, 60 min after the transition from light to dark (t6_N); (vii) 2 am, i.e. the middle of the night (t7_N), and (viii) in the end of the night period (t8_N, 24-h after the first sampling point).