Fig. 1

Construction and verification of the Δcse mutant. a Scheme of the Δcse vector construct, with a kanamycin/neomycin resistance cassette (KmR/NmR) replacing the cse gene. b Polymerase chain reaction (PCR) confirmation of two independently-obtained, fully segregated Δcse clones. Amplification of the cse gene with its upstream and downstream flanking regions in Anabaena wild-type (WT) resulted in a PCR product of 3593 bp. In the Δcse clones, replacement of cse with KmR/NmR resulted in a larger PCR product of 4075 bp. No traces of the WT PCR product in the Δcse clones indicated full segregation of the mutant. c Expression of cse in WT and Δcse clone 1 normalised to the expression of the reference gene rpoA. Error bars indicate the standard deviation from three biological replicates (n = 3)