Hydrogen cyanide production
The production of HCN was detected by spreading 1 ml of 24 h old
broth culture of Pseudomonas on the Kings B medium and incubation
of the plates with the Whatman filter paper flooded with the solution
containing 0.5% picric acid in 2% sodium carbonate located in the upper
lid of petri plate [11]. To avoid the escape of the gas, the plates were
sealed with the parafilm. After 24-48 h, yellow to orange change in the
color of the filter paper was observed.