Comparative study of antibacterial activity of two different earthworm species, Perionyx excavatus and Pheretima posthuma against pathogenic bacteria

Disease outbreaks are being increasingly recognized as a significant constraint on aquaculture production and trade affecting the economic development of the sector in many countries. Extracting and using biologically active compounds from earthworms has traditionally been practiced by indigenous people throughout the world. The aim of the present study was to shown antimicrobial activity through earthworm extract against fish bacterial pathogens. In total, 8 bacterial strains i.e. 6 gram negative viz. Aeromonas hydrophila, Pseudomonas aeruginosa, P. fluorescens, E.coli, Enterobacter aerogens and Shigella sp. and 2 gram positive viz. Staphylococcus aureus and Micrococcus luteus were identified. The extract of earthworm Perionyx excavatus, Pheretima posthuma were prepared and antimicrobial activity of the extract was determined by antimicrobial well diffusion assay. After 24 hrs of incubation period, it was observed that earthworm extract showed antibacterial activity against isolated bacterial strains. Among earthworm extract of two different species, the maximum zone of inhibition was shown against A. hydrophila by Perionyx excavatus (18.33± 0.66 mm) and P. posthuma (16.66±0.33). P. excavatus showed antibacterial activity against all pathogenic bacteria except Shigella spp. However on the other hand, P.posthuma showed antibacterial activity against A. hydrophila, P. fluorescens, E.coli, and S. aureus. The study has proved that earthworm extract can be effectively used for suppression of bacterial infection in fishes and that it can used as potential antimicrobial drug against commercial antibiotic resistance bacteria.