Increasing attention has being addressed to the urgent need of development of antimicrobial leads with novel structures because the worldwide emergence of antibiotic-resistant strains and the loss of efficacy of antibiotics to pathogens. A pET23a cDNA library from total RNA of 〞Pleurotus eryngiig〞 was constructed and screened for genes with antibacterial function by trypan blue as a vital stain. The main function of trypan blue dye is to test the loss of function of membrane permeation in dying cells. A positive clone Pe-5k was obtained. A substantially reduction of liquid cultural growth was driven by induced expression of clone Pe-5k. Sequence analysis of clone Pe-5k showed weak similarity in nucleotide BLAST but strong similarity in protein BLAST at NCBI database comparisons, suggesting an evolutionary importance of the overall structure and function.