Antimicrobial Activity of Some Plant and Algal Extracts

The use of advanced, effective and less toxic antimicrobial agents are required for the treatment of plant pathogens. In this study, hexane and ethanol extracts of two plants (Sesbania sesban and Cymbopogon citratus) and two algae species (Spirulina platensis and Scendusmus sp.) were screened for their antifungal and antibacterial activity on eight fungi (Rhizoctonia solani, Rhizopus stolonifer, Fusarium oxysporum, Aspergillus niger, Alternaria solani, Pythium debarianum, Botrytis cinerea and Penicillium digitatum) and two species of bacteria (Agrobacterium tumefaciens and Erwinia carotovora var. carotovora). Extracts of these plants and algae showed varied levels of antifungal and antibacterial activity. It was found that, the ethanol extracts of S.sesban plant and S. platensis alga had a high activity on tested fungi. On the other hand, the ethanol extracts of Scendesmus sp. alga and S. sesban plant showed the highest antibacterial activity against tested bacteria. The ethanol extract of S. sesban was the most potent fungitoxic extract against both A. niger and A. solani fungi with effective concentration (EC50) values of 0.135 and 0.011mg/L, respectively. On contrary, Scendesmus sp. ethanol extract revealed the highest inhibitory effect against E. carotovora var. carotovora bacteria.