Abstract

Objective: In order to prevent the unusual use of antibiotics and promote green aquaculture, researchers have used various herbs as medicines proposed in the aquaculture industry. One of medicinal plants is Eucalyptus camaldulensis which has been identified in different studies for the antimicrobial activity of the extract in controlling and eliminating bacterial and fungal strains which was evaluated in this study.
Methods: In this research, a variety of soxhlet and rotary extracts of ethanol, methanol, acetone and water soluble compounds and its antibacterial effect was investigated by agar diffusion method in a well. For this purpose, Vibrio Harveyi and Vibrio azureus (Kj018724.1) were isolated and identified by the sequencing of 16SrDNA.
Results: The results showed that 2.5 μg/ml extracts of ethanol, methanol, acetone and 10 μg/ml of aqueous extract of the herb had minimum inhibitory concentration (MIC)and also 10 μg/ml of ethanol, methanol, acetone and 40 μg/ml of aqueous extract conferred minimum bacterial concentration (MBC) against V. harveyi in addition, 5 μg/ml of each methanolic and acetone, 2.5 μg/ml of ethanolic and 10 μg/ml of aqueous extracts had MIC on V. azureus and 5 μg/ml of ethanolic and 10 μg/ml of methanolic and acetone and 20 μg/ml of aqueous extracts showed MBC against V. azureus. Moreover, by examining the kinetics of V. harveyi and V. azureus, the Eucalyptus camaldulensis extract had growth inhibitory effect on the both species.
Conclusion: The effects of various environmental factors such as temperature, salinity and time on the antimicrobial activity, the extract exhibited a good performance and can be used as an environmentally proper and compatible antimicrobial agent in ecological conditions and shrimp breeding areas, especially in southern Iran.

Keywords: Vibriosis; Vibrio azureus; Vibrio harveyi; Eucalyptus camaldulensis