FIG. 1.

Recombinant plasmids carrying the hcnABC region from P. fluorescens CHA0. Symbols: , genomic DNA from strain CHA0; , sites of Tn1725 insertions; ▸, orientation of kanamycin resistance and T7 promoters (P_Km and P_T7, respectively) on vector plasmids; T_φ, transcription terminator; x, time of Bal 31 digestion (minutes) and extent of deletions created by Bal 31. The HCN phenotype was assessed by qualitative and quantitative tests for HCN production as follows: −, <5 μM HCN; +, wild-type levels of HCN; overproduction of HCN.