Abstract: The crp gene (encoding the cAMP receptor protein), as a global regulatory gene, widely exists in various bacteria and exhibits different regulatory functions in different strains. P. protegens H78 is capable of producing multiple broad-spectrum antibiotics such as pyrrolnitrin (Prn), 2,4-diacetylphloroglucinol (2,4-DAPG), and pyoluteorin (Plt). In order to investigate the global regulatory effect of the crp gene on the synthesis of antibiotics including Prn, 2,4-DAPG and Pltin P. protegens H78, the influences of crp gene on the synthesis and gene expression of these three antibiotics were analyzed by gene knockout, HPLC analysis, and lacZ reporter gene analysis. The results suggested that the knockout of crp gene in H78 strain significantly inhibited Prn synthesis operon (prnABCD) expression, significantly upregulated Plt production and its operon expression, and slightly down regulated 2,4-DAPG production and its operon expression. Therefore, the crp gene exhibited a significant positive regulation on Prn biosynthesis, a significant negative regulation on Plt biosynythesis, and a small positive regulation on 2,4-DAPGbiosynthesis in P. protegens H78.

Key words: Pseudomonas protegens H78, crp gene, antibiotic synthesis regulation, pyrrolnitrin, 2,4-diacetylphloroglucinol, pyoluteorin