Phenazine
Streptomyces (terrestrial), Pseudomonas (ubiquitous),Actinomycetes (terrestrial and aquatic), Pelagibacter(aquatic) and Vibrio (aquatic) produce phenazines under the control of a quorum sensing mechanism. Phenazines are redox-active, small nitrogen-containing aromatic compounds that are used in a variety of applications (Velmurugan et al., 2020). The colour intensity ranges from blue to green to purple to yellow to red to brown. More than 50 nitrogen-containing heterocyclic pigments of bacterial origin are found in naturally occurring phenazines. Their hues are determined by their absorption spectra, which contain two peaks in the UV range and at least one peak in the visible range. Due to their capacity to undergo cellular redox cycling in the presence of oxygen and reduce NADH and NADPH to induce the formation of harmful superoxide and hydrogen peroxide, almost all phenazines are generally detrimental to the growth of bacteria and fungi. Pantoea agglomerans produces phenazines on apple blooms that help to control the phytopathogenic Erwinia amylovora , which causes fire blight (Mavrodi et al., 2010).
Phenazine physiological action is linked to redox homeostasis, which increases ATP synthesis and membrane potential maintenance (Glasser, 2017). From a biotechnological standpoint, phenazines’ physicochemical features, such as their oxidation–reduction (redox) properties, vivid pigmentation, and ability to alter colour with pH and redox state, are driving their continued study. Phenazines are still employed for a variety of purposes, including as electron acceptors and donors, fuel cell components, environmental sensors and biosensors, and as core components of anticancer drugs (Pierson & Pierson, 2010).