Sensitivity of Haloarchaea to eubacterial pigments produced by Pseudomonas aeruginosa SB1

Pseudomonas aeruginosa SB1 was isolated from conventional well water. It produced an extracellular fluorescent bright green pigment which diffused into the growth medium. The purified pigment showed absorption maxima of 690, 370, 312 nm and was identified as pyocyanine, a known inhibitor of eubacterial and eukaryotic growth. The effect of this pigment when tested on orange-red pigmented halophilic archaeal isolates showed remarkable inhibitory activity and resulted in total growth inhibition at 4.67 mg/ml pyocyanine in 24 h. The present work is the first report on eubacterial Pseudomonas aeruginosa SB1 showing anti-Haloarchaeal activity.