ANTIMICROBIAL ACTIVITY OF SOME MEDICINAL PLANTS AGAINST FISH PATHOGENS

Abstract

The present article elucidates on the antimicrobial (antibacterial and antifungal) activity of some medicinal plants (herbs) against different microbes (e.g., bacteria and fungi). Aquaculture has been a growing activity for more than 20 years worldwide. The bacterial infections are considered the major cause of mortality in aquaculture. Among the common fish pathogenic bacteria, Streptococcus agalactiae, Lactococcus garvieae, Enterococcus faecalis (all gram- positive), Aeromonas hydrophila and Yersinia ruckeri (both gram-negative) cause infectious diseases. A. hydrophila, the most common bacterial pathogen in freshwater fish, has been recognized to be the aetiological agent of many pathological conditions, including tail rot, motile Aeromonas septicemia and epizootic ulcerative syndrome as a primary pathogen. The continuous use of antimicrobial agents in aquaculture has resulted into resistant bacterial strains in the aquatic environment. Treatment of bacterial diseases with different herbs has been safely used in organic agriculture, veterinary and human medicine. Treatment with medicinal plants having antibacterial activity is a potentially beneficial alternative in the aquaculture. These herbs mitigate many of the side effects which are associated with synthetic antimicrobials. Additionally, the plant-derived phytomedicines provide a cheaper source for treatment and greater accuracy than chemotherapeutic agents. Plants have been used as traditional medicine since time immemorial to control bacterial, viral and fungal diseases. In India, 500 medicinal plant species are used against pathogenic bacteria. Recently, research has been initiated to evaluate the feasibility of herbal drugs in fish diseases. Because of the growing bacterial resistance against commercial standard and reserve antibiotics, the search for new active substances with antibacterial activity against pathogenic bacteria is of increasing importance.