**3.9 Biofilm**

Cyanobacteria form biofilms, which favor attachment on a surface to grow and produce extracellular polymers. This biofilm development in *Thermosynechococcus* is intervened by the cyclic diguanosine monophosphate (c-di-GMP) a bacterial secondary messenger [46]. Three CBCRs, SesA, B and C, in the blue/green light (ON/OFF) - c-di-GMP switch control non-motile and motile in planktonic networks [26, 47].
